WO2012005180A1 - Electrode material, electrode containing same, battery, method for producing electrode material precursor, and method for producing electrode material using the method for producing electrode material precursor - Google Patents

Abstract

Provided is an electrode material which is capable of providing an active material that has excellent water dispersibility and is also capable of providing an electrode that has excellent battery performance even in cases where the electrode material is used in the form of an aqueous slurry. Specifically disclosed is an electrode material containing an active material, which is characterized in that the active material has a structure coated with a conductive carbon material and the nitrogen atom content relative to 100% by mass of the total of the active electrode material is not less than 0.3% by mass.

Description

ELECTRODE MATERIAL AND ELECTRODE CONTAINING THE SAME, BATTERY, METHOD FOR PRODUCING ELECTRODE MATERIAL PRECURSOR, AND METHOD FOR PRODUCING ELECTRODE MATERIAL USING SAME

The present invention relates to an electrode material and the like, a method for producing an electrode material precursor, and a method for producing an electrode material. More specifically, the present invention relates to an electrode material that can be suitably used as an electrode material of a secondary battery such as a lithium ion battery, and a method for producing an electrode material precursor and a method for producing an electrode material.

In recent years, with the background of increasing interest in environmental problems, the shift of energy resources from fossil fuels such as oil and coal to electric power has progressed, and accordingly, the demand for batteries has been increasing year by year. In particular, rechargeable batteries that can be charged and discharged repeatedly are not only widely used in electronic devices such as mobile phones and laptop computers, but also in the fields of automobiles, aircrafts, and medium- and large-sized fields such as stationary power supplies. Is also expected, and research and development is actively underway.

These batteries mainly include electrodes such as a positive electrode and a negative electrode, an electrolyte, and a separator. And, with the aim of realizing a battery that exhibits higher performance, research has been conducted on each of these components. Among these, since the electrode has a great influence on the performance of the battery, various studies have been made on its material. For example, an electrode (for example, refer to Patent Document 1) in which a mixed powder of a powder of a polymer active material that electrochemically shows a redox reaction and a powder of a conductive auxiliary agent is integrally formed by hot pressing to a predetermined thickness. A positive electrode active material in which a surface of a manganese oxide that is a composite oxide mainly composed of lithium, manganese, and oxygen is coated with a conductive polymer having a π-electron conjugated structure (see, for example, Patent Document 2), and There has been proposed an electrode additive (see, for example, Patent Document 3) in which battery characteristics are improved by covering a surface of a substance (“core particle”) to be added to an electrode material with a conductive substance (“covering material”). .

In recent years, olivine-type lithium iron phosphate, which is less susceptible to resource restrictions and has high safety, has been attracting attention in place of lithium cobaltate that has been used as an electrode active material in small consumer applications. However, lithium iron phosphate has been cited as a problem that conductivity is low. Therefore, a method for producing a lithium iron phosphate / carbon nanocomposite having a core / shell structure in which the surface of lithium iron phosphate is coated with carbon to improve conductivity and can be used as an electrode material has been reported ( For example, refer nonpatent literature 1 and patent literature 4.). In addition, by introducing nitrogen into the phosphate instead of coating the surface of the active material with a carbon material, the oxygen sequence on the phosphate surface changes, and carriers involved in conduction are generated, causing the active material to A technique for reducing the resistivity has been reported (for example, see Patent Document 5).

JP 2001-118570 A (page 1-2) JP 2002-358959 A (page 1-2) JP-T-2007-522619 (page 1-2) JP 2010-40357 A (page 1-2) Japanese Patent Laying-Open No. 2005-353320 (page 1-3)

Yonggang Wang, Yarong Wang, Eiji Hosono, Kaixue Wang, Haoshen Zhou, “Ange. Chem. Int. Ed.” (Germany), Vol. 47, 2008. 7461-7465

As described above, various electrode materials have been proposed, but all of these electrode materials leave room for further improvement in terms of performance. Among them, a positive electrode for a lithium ion battery is generally kneaded with an active material containing lithium, a conductive assistant such as carbon, and a binder such as polyvinylidene fluoride together with N-methylpyrrolidone (NMP) as a solvent. The slurry is formed into a slurry, and the resulting slurry is applied to a current collector and dried. However, since NMP is a substance that is concerned about toxicity to the human body, NMP is usually recovered and reused in the drying step after applying the slurry. Therefore, using NMP as a solvent for preparing a slurry has a safety problem and a cost problem associated with recovery.

In order to solve the above-described problems, it has been proposed to use an aqueous slurry. As a positive electrode for a lithium ion battery formed using an aqueous slurry, a positive electrode formed from a positive electrode paste containing a positive electrode active material, a binder component, and water as a dispersion medium has been studied. However, since the aqueous dispersion of the positive electrode active material is usually not sufficient, it is difficult to uniformly apply the positive electrode paste on the current collector, and there is room for improvement.

The present invention has been made in view of the above situation, and an electrode material capable of obtaining an active material excellent in water dispersibility and capable of forming an electrode excellent in battery performance even when used as an aqueous slurry. The purpose is to provide.

On the other hand, it is also important to efficiently manufacture the electrode material. In the production of the electrode material, it is preferable from the viewpoint of efficient production to use a high concentration reaction raw material. However, if the reaction raw material is produced at a higher concentration, the performance of the obtained electrode material may be lowered, and it is not easy to achieve both the performance of the electrode material and the production efficiency. In the future, along with the increase in battery demand, in addition to improving battery performance, it is expected that demand for lowering costs will also increase. Therefore, developing a manufacturing method that can efficiently manufacture an electrode material that exhibits high performance is a major issue in the battery field.

Usually, the electrode material is produced by producing a precursor and then reacting the precursor with other raw materials, and the properties of the produced electrode material are also affected by the precursor used. . For this reason, as one measure for efficiently producing an electrode material exhibiting excellent performance, there has been room for further study on a method for producing a precursor as a raw material.

The present invention has also been made in view of the above-described situation, and even when a high concentration of reaction raw material is used, an electrode material precursor capable of sufficiently improving the performance of the obtained electrode material. Another object is to provide a method for manufacturing the body.

In addition, a battery created using the electrode material proposed as described above does not exhibit sufficient performance, and development of an electrode material that enables a higher performance battery is required. . The electrode active material used as such an electrode material is required to have a small particle diameter and a uniform particle diameter. However, when an active material material having a small particle diameter is used as an active material material for the electrode active material, the active material material is likely to aggregate and grow in the solution in the manufacturing process of the electrode active material. For this reason, the particle diameter of the electrode material precursor produced | generated in the manufacturing process of an electrode active material becomes large, or it becomes easy to become a thing with a nonuniform particle size. In order to produce an electrode active material having a small particle size and a uniform particle size, the precursor must have a small particle size and a uniform particle size. It is not easy to manufacture. For this reason, there was room for the device which develops the manufacturing method which can solve the subject regarding such electrode material precursor manufacture.

The present invention has also been made in view of the above situation, and provides an electrode material precursor that can be suitably used as an electrode material that has a small particle size, is uniform, and exhibits high performance. Also aimed.

Further, for example, when a lithium-containing electrode material is produced as an electrode material, it is usually produced by producing a precursor and then reacting the precursor with another raw material containing a lithium salt. Here, as one measure for producing a lithium-containing electrode material exhibiting excellent performance, there is room for further study on the process of reacting the precursor with other raw materials.

The present invention has also been made in view of the above situation, and an object thereof is to provide a method for producing a lithium-containing electrode material exhibiting high performance.

The present inventor has studied various problems related to the electrode material described above, and has focused on the dispersibility of the active material itself contained in the electrode material in an aqueous solvent. Then, the active material is coated with a conductive carbon material, and the nitrogen content of the active material is 0.3% by mass or more with respect to 100% by mass of the total amount of the active material. It has been found that the properties are remarkably improved. As a result, it has been found that an electrode excellent in battery performance can be formed even when the electrode is formed from an aqueous slurry. Thus, the inventors have conceived that the above problems can be solved brilliantly by setting the nitrogen atom content of the active material to a specific value or more, and the present invention has been achieved.

The present inventor has also conducted various studies on methods for producing an electrode material precursor capable of producing an electrode material exhibiting excellent performance by increasing the concentration of the reaction raw material. As a method for producing an electrode material precursor, precursor fine particles are produced in a solution containing an active material raw material, and an electrode material precursor is produced by forming a coating structure with a polymer produced by polymerization of monomers on the fine particles. We decided to use the method. In this production method, attention was paid to the pH of the reaction solution in the step of synthesizing the electrode material precursor using the oxidatively polymerizable monomer and the oxidizing agent as essential raw materials together with the active material raw material. Therefore, if the precursor is produced by controlling the pH of the reaction solution in the step within a specific range, the performance as an electrode material is sufficiently lowered even when the concentration of the reaction raw material during the synthesis of the precursor is increased. It has been found that it is possible to produce an electrode material precursor that enables production of an electrode material that suppresses and exhibits high performance. As a result, the inventors have found that it is possible to achieve both the performance of the electrode material and the efficiency of manufacturing the electrode material, and have conceived that the above-mentioned problems can be solved brilliantly, thereby achieving the present invention.

The present inventor has also conducted various studies on methods for producing a uniform electrode material precursor having a small particle size. As a method for producing an electrode material precursor, precursor fine particles are produced in a solution containing an active material raw material, and an electrode material precursor is produced by forming a coating structure with a polymer produced by polymerization of monomers on the fine particles. We decided to use the method. And in this manufacturing method, when an oxidation polymerizable monomer is used as a monomer for forming a coating structure with a polymer, and a precursor is synthesized while supplying an oxidizing agent into the reaction solution, the precursor generated in the reaction solution Before the fine particles come into contact with other precursor fine particles, a polymer-coated structure is formed. For this reason, even when a material having a small particle diameter is used as the active material raw material, it is suppressed that the precursor fine particles are aggregated and grown to increase the particle diameter. As a result, it has been found that a uniform electrode material precursor having a small particle size can be obtained. Furthermore, the present inventor, when synthesizing the precursor, reacts while supplying the active material raw material and / or the oxidative polymerizable monomer together with the oxidizing agent, even when the concentration of the reactive raw material is high, the electrode It has also been found that a precursor of an electrode material can be produced while sufficiently suppressing a decrease in performance as a material. Thus, the inventors have found that a precursor of an electrode material that enables a battery having excellent battery performance can be efficiently produced, and have conceived that the above-mentioned problems can be solved brilliantly, and have reached the present invention.

The inventor has further studied various methods for producing a lithium-containing electrode material capable of exhibiting high performance. And as one point of focus, attention was focused on the step of reacting the precursor and other raw materials containing lithium salt among all the steps for producing the lithium-containing electrode material. Thus, in this step, it has been found that a more homogeneous lithium-containing electrode material can be obtained if the reaction proceeds in a state where it is mixed as uniformly as possible when the precursor reacts with other raw materials. It has been found that such a lithium-containing electrode material can exhibit higher performance than before.
Here, when the precursor fine particles are mixed with an electrode material precursor having a coating structure with a polymer and another raw material containing a lithium salt in the presence of a solvent to prepare a mixture, the precursor and the others that are usually powdery A mixture is prepared by mixing these raw materials in the form of a paste in the presence of a solvent. Therefore, it becomes possible to mix the powders more uniformly than the dry mixing of the powders. When the mixture mixed in such a paste is heat-treated, the active material fine particles become homogeneous, and it is found that a lithium-containing electrode material having a structure in which such active material fine particles are coated with a carbon component can be obtained. It was. It has been found that such a lithium-containing electrode material exhibits high performance.

The present inventor has also found the following method as another method for producing a lithium-containing electrode material capable of exhibiting high performance. Precursor fine particles are produced in a solution in which the active material raw material, oxidative polymerizable monomer, and oxidizing agent are essential raw materials, and the concentration of the essential raw materials is 3 to 60% by weight with respect to 100% by weight of the solution containing all precursor raw materials. Let At the same time, a coating structure is formed on the precursor fine particles by a polymer formed by polymerization of an oxidative polymerizable monomer. A mixture is prepared using the electrode material precursor produced thereby and a lithium salt having a melting point of 400 ° C. or lower as essential components. Then, the mixture is heat-treated. It has been found that a lithium-containing electrode material exhibiting high performance can be obtained by such a method. If it does in this way, in a heat treatment process, precursor particulates and lithium salt will react, and active material particulates will be generated. At this time, the lithium salt is melted and liquefied up to a temperature at which the active material fine particle formation reaction occurs. Thus, the precursor and other raw materials are mixed in a paste form to prepare a mixture. Therefore, a uniform mixture can be prepared, and similarly to the above-described method, the active material fine particles become homogeneous and a lithium-containing electrode material exhibiting high performance can be obtained.
As a result, the inventors have found that a lithium-containing electrode material that enables a battery having excellent battery performance can be produced, and have conceived that the above problems can be solved brilliantly, and have reached the present invention. is there.

That is, the present invention is an electrode material containing an active material, and the active material has a structure coated with a conductive carbon material, and a nitrogen atom content with respect to 100% by mass of the active material is 0.3% by mass. % Or more of the electrode material.

A method of producing an electrode material precursor by forming precursor fine particles in a solution containing an active material raw material and forming a coating structure with a polymer produced by polymerization of monomers on the fine particles, The method also includes a method for producing an electrode material precursor including a step of using an oxidative polymerizable monomer and an oxidant as an essential raw material together with an active material raw material, and a pH of the solution of 0.3 or more and 3.0 or less. One.

A method of producing an electrode material precursor by forming precursor fine particles in a solution containing an active material raw material and forming a coating structure of a polymer formed by polymerization of monomers on the fine particles, the production method comprising: An electrode material precursor manufacturing method including a step of synthesizing a precursor while supplying an oxidizing agent into an active solution and supplying an oxidizing agent together with an active material raw material as an essential raw material is also one aspect of the present invention. One.

A method for producing a lithium-containing electrode material in which active material fine particles have a coating structure with a carbon component, wherein the precursor fine particles include an electrode material precursor having a coating structure with a polymer and a lithium salt as essential components. A method for producing a lithium-containing electrode material comprising a step of preparing a mixture containing the essential components in the presence of a solvent and then heat-treating the mixture is also one aspect of the present invention.
The present invention is also a method for producing a lithium-containing electrode material in which active material fine particles have a coating structure of a carbon component, wherein the production method comprises an oxidatively polymerizable monomer and an oxidizing agent as an essential raw material together with an active material raw material. Polymers produced by forming precursor fine particles in a solution in which the concentration of the raw material is 3 to 60% by mass with respect to 100% by mass of the solution containing all precursor raw materials, and polymerization of the above-mentioned fine particles by oxidation polymerizable monomer A step of producing an electrode material precursor by forming a covering structure according to the method, and a step of heat-treating the mixture after preparing a mixture containing the electrode material precursor and a lithium salt having a melting point of 400 ° C. or lower as essential components It is also a manufacturing method of the lithium containing electrode material containing.
The present invention is described in detail below.

The electrode material of the present invention includes an active material (electrode active material). Examples of the active material include ternary systems such as lithium cobaltate, lithium manganate, lithium nickelate, nickel cobalt lithium manganate, and phosphorus. Examples thereof include active materials having an olivine structure such as lithium iron oxide and lithium manganese phosphate. Lithium cobaltate, lithium manganate, lithium iron phosphate, and lithium manganese phosphate are preferable, and lithium iron phosphate is more preferable. Moreover, it is preferable that it does not contain nitrogen. One kind of these active materials may be used, or two or more kinds may be used in combination. When two or more active materials are used in combination, the nitrogen atom content may be 0.3% by mass or more with respect to the total amount of 100% by mass of all the active materials including plural types of active materials.
Moreover, as long as the active material is included, other components may be included.

The active material has a structure covered with a conductive carbon material. The structure covered with the conductive carbon material represents a coating structure in which the active material fine particles (active material core) are the core part and the conductive carbon material is the shell part. The active material fine particles (active material core) are, for example, metal oxides formed by a reaction between a precursor fine particle (precursor core) described later and a compound serving as a lithium source described later.
Here, the covering structure (core / shell structure) includes not only a form in which the core part is completely covered by the shell part (complete covering structure) but also a part in which the core part is not covered by the shell part. A form (partial covering structure) in which the core part is covered with the shell part is also included.

The active material has a nitrogen atom content of 0.3% by mass or more with respect to 100% by mass of the total amount of active materials. When the content of nitrogen atoms in the active material is in such a range, the dispersibility of the active material in the aqueous solvent is remarkably improved. It is possible to form an electrode with excellent performance. The nitrogen atom content of the active material is preferably 0.35% by mass or more with respect to 100% by mass of the total amount of the active material. More preferably, it is 0.4 mass% or more, More preferably, it is 0.45 mass% or more.
In addition, for example, as described later, an active material raw material, an oxidative polymerizable monomer having a nitrogen atom, and an oxidant are reacted in a solution, and are generated by polymerization of the oxidative polymerizable monomer around the active material precursor core. In the case where an active material precursor having a coating structure formed of a nitrogen-containing polymer is produced, and an active material is produced by heat-treating a mixture containing the active material precursor and a lithium salt, the active material is contained. Since most of the nitrogen atoms to be derived are derived from nitrogen atoms of the oxidative polymerizable monomer, the fact that the active material contains many nitrogen atoms means that the active material precursor containing many nitrogen-containing polymers is used. Means that Here, when the active material precursor is manufactured so as to contain a large amount of the nitrogen-containing polymer, the active ingredients for exhibiting the battery performance in the active material will be relatively reduced. In the case of producing an active material, if the nitrogen atom content of the active material is too high, the battery performance of the active material may be reduced. Therefore, the nitrogen atom content of the active material is preferably 10% by mass or less with respect to 100% by mass of the total amount of the active material. More preferably, it is 5 mass% or less, More preferably, it is 3 mass% or less.
Note that the nitrogen atom content of the active material can be measured by the apparatus and measurement conditions described in the examples described later.

The active material preferably has a contact angle with water of 30 ° or less. When the active material has a contact angle with respect to water in such a range, good water dispersibility is exhibited, and the effects of the present invention can be sufficiently exhibited. More preferably, it is 20 degrees or less as a contact angle with respect to the water of an active material, More preferably, it is 10 degrees or less. Furthermore, it is most preferable that the liquid droplet is absorbed by the active material and does not show a contact angle.
When the electrode material of the present invention contains two or more active materials, at least one of them preferably has a contact angle with water of 30 ° or less. More preferably, all kinds of active materials contained in the electrode material have a contact angle with water of 20 ° or less.
In addition, the contact angle with respect to the water of an active material can be calculated | required with the apparatus and measurement conditions which are described in the Example mentioned later.

The method for producing an active material in which the nitrogen atom content is 0.3% by mass or more with respect to 100% by mass of the total amount of the active material is not particularly limited as long as the nitrogen atom content is 0.3% by mass or more. For example, as described above, an active material raw material, an oxidative polymerizable monomer having a nitrogen atom, and an active material precursor core obtained by reacting an oxidant in a solution are produced by polymerization of the oxidative polymerizable monomer. An active material precursor (electrode material precursor) having a coating structure formed of a nitrogen-containing polymer is manufactured, and a mixture containing the active material precursor and a lithium salt is heat-treated (fired) to produce an active material (electrode active material). In the method for producing the active material (electrode active material) by the method for producing the material) (that is, the method for producing the electrode material precursor of the present invention to be described later and the method for producing the lithium-containing electrode material of the present invention), A method using an oxidatively polymerizable monomer having a nitrogen atom as a monomer), an active material precursor or an active material obtained by a method usually used for obtaining an active material precursor or an active material, or an electrode of the present invention described later A monomer having a nitrogen atom is polymerized or polycondensed on the surface of the active material precursor obtained by the material precursor production method or the active material (electrode active material) obtained by the lithium-containing electrode material production method of the present invention described later. A method for producing an active material having a structure covered with a conductive carbon material by producing an active material having a coating structure formed of a nitrogen-containing polymer produced by heat treatment, and a normal active material precursor or active material Of active material precursor or active material obtained by the method used to obtain the electrode material precursor of the present invention to be described later An active material precursor obtained by immersing and drying an active material precursor obtained by the method or an active material (electrode active material) obtained by the method for producing a lithium-containing electrode material of the present invention described later in a polymer solution containing nitrogen atoms Alternatively, a method of producing an active material having a structure in which an active material is polymer-coated and then coated with a conductive carbon material by heat treatment, and the like can be given.
Moreover, it is also possible to carry out by combining these methods. As will be described later, performing the heat treatment in a nitrogen atmosphere also contributes to increasing the nitrogen atom content of the active material.
In the active material manufacturing method described above, the nitrogen atoms contained in the active material are contained in the conductive carbon material covering the active material, but in the present invention, the nitrogen atoms contained in the active material are: It is preferably contained in the conductive carbon material that covers the active material. When the active material has such a structure, the water dispersibility of the active material becomes more excellent. Furthermore, from the viewpoint of contribution of the active material to water dispersibility, the nitrogen atom is more preferably present on the surface of the conductive carbon material. Whether nitrogen atoms exist on the surface of the conductive carbon material can be analyzed using XPS (X-ray photoelectron spectroscopy). Since the elemental analysis of the extreme surface (several nm) of the sample can be performed by XPS analysis, it can be confirmed that nitrogen atoms contained in the active material are contained in the conductive carbon material covering the active material.

Examples of the monomer having a nitrogen atom include N-vinyl compounds such as N-vinyl-2-pyrrolidone, N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylformamide, and N-methyl-N-vinylacetamide. ; (Meth) acrylamide derivatives such as (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-ethyl (meth) acrylamide, diacetone (meth) acrylamide; N, N-dimethyl Polymerizable unsaturated group-containing amide compounds such as aminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide and acryloylmorpholine; nitrogen atom-containing radical polymerizable monomers such as aniline, pyrrole and vinylcarbazole Nitrogen atom Yes oxidative polymerizable monomer, .epsilon.-caprolactam, undecane lactam, lauryllactam, hexamethylenediamine, nonanediamine, methyl pentamethylene diamine, p- phenylene diamine, and a nitrogen atom-containing polycondensable monomers such as m- phenylenediamine.

Examples of the polymer having a nitrogen atom include compounds having a vinylpyrrolidone structure such as polyaniline derivatives, polypyrrole derivatives, poly (N-substituted maleimide), polyvinylcarbazole, and polyvinylpyrrolidone; polyacrylamide, poly (N, N-dimethylacrylamide), poly N-substituted polyacrylamides such as (N-isopropylacrylamide); polyethyleneimine derivatives; polyacrylonitrile; etc. and copolymers thereof.

The active material has a structure coated with a conductive carbon material, and the other structure is not particularly limited as long as the nitrogen atom content is 0.3% by mass or more with respect to the total amount of the active material of 100% by mass. The preferred structure of the active material that can be suitably used as the electrode material of the present invention will be described.
As described above, the active material has a structure covered with a conductive carbon material. However, the active material having a structure covered with a conductive carbon material is an active material precursor fine particle (active material precursor). Active material precursor (which is also simply referred to as a precursor) having a coating structure made of a conductive carbon material precursor (polymer), and other necessary materials are mixed and heat-treated (firing). Or a coating structure made of a conductive carbon material precursor (polymer) is formed on the active material or active material precursor obtained by the method usually used for obtaining the active material or active material precursor. It can manufacture by heat-processing (baking).
In the firing step, active material fine particles (active material core) are generated, the polymer around the fine particles is carbonized, and the active material core has a core-shell structure in which the active material core is coated with carbon (shell). Thus, an active material having a structure coated with carbon, which is a conductive substance, exhibits excellent performance as a battery electrode material, and can be suitably used as a battery material that exhibits high battery performance. .
Hereinafter, a preferable method for producing the electrode material of the present invention will be described. The method for producing such an electrode material is also the present invention. That is, the present invention is also an invention relating to a method for producing an electrode material precursor and a lithium-containing electrode material. Moreover, the manufacturing method which combined two or more manufacturing methods of the electrode material precursor of this invention and lithium-containing electrode material which are demonstrated below is suitable implementation of the manufacturing method of the electrode material precursor of this invention and lithium-containing electrode material. It is a form.

As a method for producing the electrode material precursor, it is preferable to employ a method in which precursor fine particles are generated in a solution containing an active material raw material and a coating structure is formed on the fine particles by polymerization of a monomer. . By such a method, it is possible to produce a uniform electrode material precursor in which the precursor fine particles have a coating structure of a polymer and the particle diameter is small.

The method for producing an electrode material precursor of the present invention includes a step of synthesizing a precursor while supplying an oxidant into a reaction solution using an oxidative polymerizable monomer and an oxidant as essential raw materials together with an active material. preferable. When the manufacturing method includes such a step, the precursor fine particles generated in the reaction solution form a coating structure with a polymer before coming into contact with other precursor fine particles. It is possible to produce a uniform electrode material precursor that is suppressed from growing and having a large particle size and a small particle size. In this synthesis step, the method for supplying the oxidizing agent into the reaction solution is not particularly limited as long as it is supplied while performing the reaction for synthesizing the precursor, and may be continuous or intermittent. However, a method in which the oxidizing agent is supplied in a plurality of times in the reaction solution is preferable, and a method in which a solvent is added to the oxidizing agent to form a solution, and a method in which the reaction solution is added dropwise little by little is more preferable.
When supplying the oxidizing agent dropwise into the reaction solution, the supply is preferably performed over 1 to 360 minutes. More preferably, it is 5 to 180 minutes.
Such a method for producing an electrode material precursor including a step of synthesizing a precursor while supplying an oxidizing agent as an essential raw material together with an active material raw material while supplying the oxidizing agent into the reaction solution is the present invention. This method is suitable as a method for producing a precursor of the electrode material, and is also one aspect of the present invention.

Examples of the oxidizing agent include iron (III) chloride, iron (III) sulfate, iron (III) nitrate, iron (III) acetylacetonate, iron (III) bromide, iron (III) citrate, iron fluoride ( Trivalent iron salts such as III), trivalent manganese salts such as manganese chloride (III), manganese sulfate (III), manganese acetate (III), manganese fluoride (III), manganese phosphate (III), etc. And a raw material for active material fine particles; peroxodisulfates such as ammonium peroxodisulfate, sodium peroxodisulfate, potassium peroxodisulfate, sodium peroxoborate, potassium peroxoborate 1 or 2 or more of peroxoborate such as ammonium peroxoborate, one that acts only as an oxidizing agent such as hydrogen peroxide It can be used. Of these, trivalent iron salts and trivalent manganese salts are preferred as materials that have an oxidizing action and become active material fine particles, more preferably iron (III) chloride, manganese chloride. (III). Peroxodisulfate is preferable as an agent acting only as an oxidizing agent, and ammonium peroxodisulfate is more preferable.
In addition, it is one of the suitable embodiment of this invention that an oxidizing agent is a compound containing the salt of a trivalent iron. Among the trivalent iron salts, iron chloride (III) and iron nitrate (III) are more preferable. Other than trivalent iron salts, manganese chloride (III) and ammonium peroxodisulfate are preferred.

The amount of the oxidizing agent supplied in the synthesis step is preferably 10 to 1000% by mass with respect to 100% by mass of the oxidative polymerizable monomer used in the synthesis step. When the amount of the oxidizing agent is less than 10% by mass, the oxidative polymerizable monomer does not sufficiently undergo a polymerization reaction, and there is a possibility that a sufficient coating structure cannot be formed on the precursor fine particles. On the other hand, when the amount of the oxidizing agent is more than 1000% by mass, the polymerization of the oxidative polymerizable monomer proceeds excessively, and gelation may occur in the synthesis step, and the reaction may not proceed. More preferably, it is 50 to 800% by mass, and still more preferably 100 to 500% by mass with respect to 100% by mass of the oxidatively polymerizable monomer.
The electrode material precursor production method of the present invention produces fine particles having a structure in which precursor fine particles are coated with a polymer formed by polymerizing an oxidative polymerizable monomer. Hereinafter, the fine particles having such a coating structure are referred to as a precursor (electrode material precursor) manufactured by the method for manufacturing an electrode material precursor of the present invention, or simply a precursor (electrode material precursor). Further, the precursor fine particles coated with the polymer are also referred to as an active material precursor core and a precursor core.
For example, as will be described later, when the precursor fine particles are synthesized using iron (III) chloride as the oxidizing agent and ammonium dihydrogen phosphate as the active material raw material, and the coating structure is formed by the polymer, the precursor fine particles (Precursor core) becomes iron phosphate (FePO ₄ ), and a fine particle having a structure in which a polymer is coated on iron phosphate is produced by the method for producing an electrode material precursor of the present invention (electrode material precursor). It is.

When supplying the oxidizing agent as a solution to the reaction solution, the concentration of the oxidizing agent solution is preferably 1 to 60% by mass. More preferably, it is 5 to 50% by mass.
As the solvent for dissolving the oxidizing agent, aprotic polar solvents such as water, water-soluble alcohols such as methanol and ethanol, dimethyl sulfoxide, N, N-dimethylformamide, acetonitrile and hexamethylphosphoric triamide are preferable. More preferably, it is water.

The active material raw material used in the synthesis step includes a nonmetallic compound containing a nonmetallic element and / or a metal containing a metallic element such as phosphorus, manganese, cobalt, nickel, titanium, silicon, and vanadium. Compounds are included. Such non-metallic compounds and / or metal compounds include ammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate, potassium hydrogen phosphate, phosphorus Compounds containing phosphorus such as potassium dihydrogen oxide, potassium phosphate, dicalcium phosphate, primary calcium phosphate, calcium phosphate, calcium phosphite; cobalt acetate (II), cobalt bromide (II), cobalt carbonate (II), cobalt chloride ( II), cobalt fluoride (II), cobalt hydroxide (II), cobalt nitrate (II), cobalt oxalate (II), cobalt phosphate (II) and other compounds containing manganese; manganese (II) chloride, sulfuric acid Manganese (II), manganese acetate (II), manganese fluoride (II), Compounds containing manganese such as manganese (II) oxide; nickel acetate (II), nickel bromide (II), nickel carbonate (II), nickel chloride (II), nickel fluoride (II), nickel hydroxide (II) ), Nickel nitrate (II), nickel stearate and other nickel-containing compounds; titanium chloride (IV), titanium chloride (III), titanium tetraisopropoxide, titanium tetrabutoxide, titanium sulfate (IV), etc. Compounds containing titanium; compounds containing silicon such as tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane and tetrachlorosilane; one or more of compounds containing vanadium such as vanadium chloride (III) and vanadium hydroxide Can be used. Among these, compounds containing phosphorus such as ammonium hydrogen phosphate, ammonium dihydrogen phosphate, and ammonium phosphate; compounds containing manganese such as manganese (II) chloride, manganese (II) sulfate, and manganese (II) acetate are used. It is preferable. More preferably, it is a compound containing phosphorus.
That is, it is one of the preferred embodiments of the present invention that the active material raw material is a compound containing phosphorus.

In the above electrode material precursor production method, the essential materials, that is, the active material raw material, the oxidative polymerizable monomer, and the oxidizing agent are used in an amount of 100% by mass of the solution containing all precursor raw materials used for the production of the precursor. The content is preferably 3 to 60% by mass. With such a concentration, the oxidatively polymerizable monomer is effectively polymerized on the surface of the precursor fine particles, and a sufficient coating structure can be formed.
That is, it is one of the preferred embodiments of the present invention that the concentration of the essential raw material is 3 to 60% by mass with respect to 100% by mass of the solution containing all precursor raw materials.
More preferably, the concentration of the essential raw material is 5 to 45% by mass, more preferably 7 to 40% by mass with respect to 100% by mass of the solution containing all the precursor raw materials used for the production of the precursor. is there.
In addition, all the precursor raw materials used for manufacture of a precursor here include all the raw materials used for precursor synthesis | combination, supplying a precursor raw material in a reaction solution so that it may mention later. When carrying out the reaction, the total amount of raw material supplied is included. That is, the total amount of the solution containing all precursor raw materials used in the production of the precursor is the required amount of active material raw materials, oxidatively polymerizable monomers, oxidizing agents, solvents, and other additives (if any). It is the sum.
Further, the concentration of the essential raw material refers to the mass fraction of the total required amount of the active material raw material, the oxidative polymerizable monomer, and the oxidizing agent with respect to the solution. When the essential raw material contains a hydrate, the total amount including the hydrated water is calculated.

The oxidatively polymerizable monomer used in the synthesis step is not particularly limited as long as it can be polymerized to form a film on the precursor fine particles, and includes aniline, pyrrole, thiophene, phenol, vinylcarbazole, isothia 1 type (s) or 2 or more types, such as a compound which consists of naphthene, furan, and those derivatives, can be used.
Among these, aniline, thiophene, and pyrrole are preferable. More preferred are aniline and pyrrole, and most preferred is aniline.
That is, it is one of the preferred embodiments of the present invention that the oxidatively polymerizable monomer is aniline.

The oxidatively polymerizable monomer is preferably 5 to 200% by mass with respect to 100% by mass in total of the nonmetallic compound and the metal compound used in the synthesis step. If the amount of the oxidatively polymerizable monomer is less than 5% by mass, there is a possibility that a sufficient coating structure cannot be formed on the precursor fine particles. On the other hand, when the amount of the oxidatively polymerizable monomer is more than 200% by mass, the unreacted oxidatively polymerizable monomer increases, which may inhibit the synthesis reaction of the electrode material precursor. The amount of the oxidatively polymerizable monomer is more preferably 10 to 150% by mass, still more preferably 20 to 100% by mass with respect to 100% by mass in total of the nonmetallic compound and the metal compound.
In addition, the description “with respect to the total of 100% by mass of the nonmetallic compound and the metal compound” does not mean that the active material raw material always includes both the nonmetallic compound and the metal compound, but includes both. In this case, it means that the content of the oxidative polymerizable monomer is preferably as described above with respect to the total, and when the active material raw material contains only one of a nonmetallic compound and a metallic compound, It means that the content of the oxidatively polymerizable monomer is preferably as described above with respect to 100% by mass of the nonmetallic compound or the metallic compound contained in the active material raw material.

In the above synthesis step, the active material raw material and the oxidative polymerizable monomer may be added in advance in the reaction solution, or may be reacted while being supplied into the reaction solution. Alternatively, the reaction is preferably performed while supplying the oxidatively polymerizable monomer into the reaction solution. In this way, an electrode material precursor that exhibits excellent performance can be produced even when the raw material is charged at a high concentration. In general, when an electrode material precursor manufactured using a high concentration of raw materials is used, the resulting battery may not have sufficiently high performance. This is because, in the step of synthesizing the electrode material precursor, when the concentration of the raw material is increased in the reaction solution, the raw materials are likely to come into contact with each other and aggregation is likely to occur. Is one of the causes. However, when the reaction is performed while supplying the active material raw material and / or the oxidative polymerizable monomer in the reaction solution in addition to the oxidizing agent, the supplied raw material reacts sequentially, and a new raw material is added to the reaction solution. Even if the amount of raw materials used in the reaction is increased relative to the amount of the reaction solution and the concentration of the raw materials is increased, the reaction solution contains a high concentration of reaction raw materials. Therefore, it is possible to efficiently produce a large number of electrode material precursors that exhibit excellent performance.
Thus, the manufacturing method of the electrode material precursor of the present invention includes the step of synthesizing the precursor while supplying the active material and / or the oxidizable polymerizable monomer while supplying the oxidizing agent into the reaction solution. This is also one of the preferred embodiments of the present invention.

The step of synthesizing the precursor while supplying the active material raw material and / or the oxidative polymerizable monomer while supplying the oxidizing agent into the reaction solution includes (1) oxidizing agent in the solution containing the active material raw material. A step of synthesizing a precursor while supplying an oxidizable polymerizable monomer, and (2) supplying a precursor while supplying an oxidant into a solution containing the oxidizable polymerizable monomer and supplying an active material raw material. There are three steps: a step of synthesizing, and (3) a step of synthesizing a precursor while supplying an active material raw material and an oxidative polymerizable monomer while supplying an oxidizing agent into a solution containing a solvent. The manufacturing method of the electrode material precursor including the synthesis step is also a preferred embodiment of the present invention, but among these, the manufacturing method including the step (3) is more preferable.

In the case of synthesizing the precursor by the step (1), a mode in which the supply of the oxidizing agent into the reaction solution is started first and then the supply of the oxidation polymerizable monomer is started is preferable. By doing so, the reaction of the active material raw material can proceed before the polymerization reaction of the oxidative polymerizable monomer, and the precursor core generated by the reaction of the active material raw material is generated by the polymerization reaction of the oxidative polymerizable monomer. Fine particles having a core / shell structure covered with the polymer thus prepared can be produced more reliably.
The core / shell structure has not only a form in which the core part is completely covered by the shell part (complete covering structure) but also a part where the core part is not covered by the shell part and the core part is the shell part. In this case, the electrode material precursor manufacturing method of the present invention can form a sufficient covering structure, and can be used as an electrode. It is possible to produce an electrode material precursor that is a raw material for an electrode active material that exhibits excellent characteristics.

When the precursor is produced by supplying the active material raw material and / or the oxidative polymerizable monomer to the reaction solution, the method for supplying the active material raw material and / or the oxidative polymerizable monomer to the reaction solution is not particularly limited and is continuous. It may be intermittent or may be intermittent, but a method of supplying the active material raw material and / or the oxidatively polymerizable monomer into the reaction solution in a plurality of times is preferred, and the reaction solution is added dropwise little by little. The method of adding is more preferable.
When supplying the active material raw material and / or the oxidative polymerizable monomer dropwise into the reaction solution, the supply is preferably performed over 1 to 360 minutes. More preferably, it is 5 to 180 minutes.

When supplying the active material raw material and / or the oxidatively polymerizable monomer dropwise to the reaction solution, they can be supplied after being dissolved in a solvent as necessary. In this case, the concentration of the active material raw material solution and the oxidation polymerizable monomer solution is preferably 1 to 60% by mass. More preferably, it is 5 to 50% by mass.
Solvents for dissolving active material raw materials and oxidative polymerizable monomers include water, water-soluble alcohols such as methanol and ethanol, aprotic polar solvents such as dimethyl sulfoxide, N, N-dimethylformamide, acetonitrile and hexamethylphosphoric triamide Is preferred. More preferred are water, methanol, ethanol, N, N-dimethylformamide and mixtures thereof. Particularly preferred is water.

Examples of the solvent contained in the reaction solution include water, water-soluble alcohols such as methanol and ethanol, aprotic polar solvents such as dimethyl sulfoxide, N, N-dimethylformamide, acetonitrile, and hexamethylphosphoric triamide. 1 type (s) or 2 or more types can be used. Among these, water, methanol, ethanol, and N, N-dimethylformamide are preferable, and water is more preferable. In particular, when the concentration of raw materials used for precursor synthesis is increased, water and N, N-dimethylformamide, dimethyl sulfoxide, acetonitrile, hexamethylphosphoric acid are used to sufficiently dissolve the oxidatively polymerizable monomer. It is preferable to use a mixture of an aprotic polar solvent such as triamide and a solvent such as water-soluble alcohol such as methanol and ethanol.
In the reaction solution before starting the supply of the material supplied to the reaction solution, the total of the active material raw material and the oxidative polymerizable monomer contained in the reaction solution before the start of the supply of the material supplied to the reaction solution is 100% by mass. On the other hand, the solvent is preferably contained in an amount of 10 to 500% by mass.

In the above synthesis step, the pH of the reaction solution is preferably 0.3 to 3.0. When the pH of the reaction solution is in such a range, a battery using the obtained electrode material can maintain high battery performance. If the pH is higher than 3.0, it is considered that there is a high possibility of precipitation of various hydroxides in addition to the precursor fine particles, and the performance of the battery using the obtained electrode material may not be sufficiently high. There is. Moreover, when pH is lower than 0.3, it is thought that it becomes difficult to produce | generate a precursor fine particle in a solution, and there exists a possibility that the yield of a precursor may fall. The pH of the reaction solution is more preferably 0.4 to 2.5, and still more preferably 0.5 to 2.0.
Such a method for producing an electrode material precursor including a step of adjusting the pH of the solution to 0.3 or more and 3.0 or less is a method suitable as a method for producing the precursor of the electrode material of the present invention, It is also one of the present inventions.
Thus, a method for producing an electrode material precursor including the step of setting the pH of the solution to 0.3 to 3.0 is also a preferred embodiment of the present invention.
The pH of the reaction solution can be adjusted by changing the type and composition of the active material raw material or adding an acidic substance or a basic substance to the reaction solution.

In the method for producing an electrode material precursor, it is preferable that the pH of the solution is within the above range at any point in the synthesis step. More preferably, the pH of the solution is reduced when the supply of the oxidizing agent is completed. The pH of the solution is more preferably in the above range, and more preferably when the supply of the oxidant is completed and when all the supply of the essential raw materials supplied into the reaction solution in the synthesis step is completed. That is the above range. Most preferably, the pH of the solution is in the above range from the start of the reaction for synthesizing the precursor in the reaction solution to the end of the synthesis step.
Moreover, it is also one of the preferred embodiments of the present invention that the pH of the solution when all the essential raw materials are mixed is 0.3 or more and 3.0 or less.

Examples of the acidic substance include mineral acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and boric acid; organic acids such as acetic acid, benzoic acid, formic acid, trichloroacetic acid, trifluoromethanesulfonic acid and sulfonic acid; zeolites and mixed oxides 1 type (s) or 2 or more types, such as inorganic acids, etc. can be used.

Examples of the basic substance include organic amines such as ammonia, ethylamine, diethylamine, triethylamine, and hydroxyethylamine, aromatic amines such as aniline, methylaniline, dimethylaniline, phenylenediamine, toluylenediamine, and pyridine, lithium hydroxide, and hydroxide. Alkaline metal hydroxides such as sodium and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, strontium hydroxide and barium hydroxide, alkali metals such as ammonium carbonate, lithium carbonate, sodium carbonate and potassium carbonate 1 type (s) or 2 or more types, such as carbonates, can be used. More preferred are organic amines such as ammonia, diethylamine and triethylamine and aromatic amines such as aniline, methylaniline, dimethylaniline, phenylenediamine, toluylenediamine and pyridine, and most preferred are ammonia and aniline.

The reaction temperature in the synthesis step is preferably 5 to 100 ° C. If the reaction temperature is lower than 5 ° C, the reaction may not proceed sufficiently. If the reaction temperature is higher than 100 ° C, the oxidatively polymerizable monomer is rapidly polymerized, and a sufficient coating structure cannot be formed on the precursor fine particles. There is a fear. More preferably, it is 15 to 80 ° C.
The reaction time is preferably 10 minutes to 10 hours. More preferably, it is 30 minutes to 6 hours. The reaction time here means from the time when the reaction for synthesizing the precursor in the reaction solution starts to the end of the synthesis reaction, and the time required to supply the oxidizing agent or the like is also included in the reaction time. .

The slurry precursor obtained in the synthesis step is separated and recovered from the solution. As a method for separating and recovering the precursor from the solution, centrifugation, filtration, decantation and the like can be used, but it is preferable to carry out by centrifugation. It is preferable that the recovered precursor is further dispersed again by adding the solvent used in the synthesis step, and this is centrifuged to improve the purity of the precursor by performing a washing operation for recovering the precipitate of the precursor a plurality of times. . In the separation, a flocculant may be used in order to increase the efficiency of separation and recovery. As the flocculant, any of nonionic, anionic, cationic, and emulsion flocculants can be used.

The recovered precursor is preferably used in subsequent steps after being dried to a powder. The precursor is preferably dried at a temperature of 50 to 200 ° C. and a pressure of 0.001 MPa to normal pressure for 0.5 to 24 hours. By such drying, the precursor can be sufficiently dried to form a powder.

The precursor powder after drying preferably has an average primary particle size of the precursor powder (fine particles) of 5 to 1000 nm. When the average primary particle size of the fine particles of the precursor is in such a range, the electrode active material produced using the precursor has a small particle size and exhibits excellent performance. The average primary particle size of the fine particles of the precursor is more preferably 10 to 800 nm, and still more preferably 20 to 500 nm.
The average primary particle size of the fine particles of the precursor is represented by the average primary particle size of 100 particles observed with a transmission electron microscope (TEM).
The precursor fine particles mean not only the precursor core but also the fine particles of the entire precursor including the shell portion.

The dried precursor powder has a core / shell structure in which precursor fine particles (precursor core) are coated with a polymer obtained from an oxidatively polymerizable monomer, and exhibits excellent performance. It can be suitably used as a raw material.
Next, a process for producing an electrode active material using the precursor obtained by the method for producing an electrode material precursor of the present invention (method for producing a lithium-containing electrode material of the present invention) will be described.

The electrode active material can be produced by further mixing other necessary materials with the dried powder of the precursor produced by the method for producing an electrode material precursor of the present invention, followed by heat treatment (firing). In the firing step, electrode active material fine particles (electrode active material core) are generated, and a polymer obtained from an oxidative polymerizable monomer around the fine particles is carbonized, and the electrode active material core is carbon that is a conductive carbon material. It has a core-shell structure covered with (shell). Thus, an electrode active material having a structure coated with carbon, which is a conductive substance, exhibits excellent performance as a battery electrode material, and is preferably used as a battery material that exhibits high battery performance. it can.
The electrode active material having such a coating structure is referred to as an electrode active material (electrode material) produced by the method for producing a lithium-containing electrode material of the present invention, or simply an electrode active material (electrode material). Electrode active material fine particles coated with carbon are also referred to as active material fine particles and electrode active material cores. Electrode active material fine particles (active material fine particles, electrode active material core) are metal oxides formed by reaction between precursor fine particles (precursor core) and a compound serving as a lithium source described later.

The material mixed with the precursor includes a compound that becomes a lithium source. As a result, an electrode active material having a lithium-containing metal oxide capable of reversibly removing and inserting lithium ions as an electrode active material core can be obtained.
When an iron-based compound such as iron (III) chloride is used as the oxidizing agent, a compound having a melting point of 400 ° C. or lower is preferably used as the lithium salt. When such a lithium salt is used, the active material fine particles are considered to be homogeneous, and the resulting electrode active material exhibits high performance. This is because, when an iron-based compound such as iron (III) chloride is used as the oxidizing agent, the reduction from Fe (III) to Fe (II) is performed in the process of firing the precursor and the material containing the iron-based compound. Lithium salt is easily converted into Fe and other active material raw materials when Fe (III) is reduced by using a lithium compound that melts and liquefies up to the temperature at which this reduction is performed. This is considered to be because the reaction to generate the electrode active material can be efficiently performed. More preferably, among lithium salts having a melting point of 400 ° C. or lower, lithium organic acid is preferable from the viewpoint of having in its molecular structure a hydrocarbon that can contribute to the reduction reaction of Fe.
Using such a precursor obtained by the method for producing an electrode material precursor of the present invention and a lithium salt having a melting point of 400 ° C. or lower, particularly an organic acid lithium having a temperature of 400 ° C. or lower, an electrode active material is obtained. The manufacturing method is also one of the preferred embodiments of the present invention.

Examples of the lithium salt that serves as the lithium source include lithium acetate, lithium formate, lithium oxalate, lithium phosphate, lithium salicylate, lithium stearate, lithium citrate, and other organic acid salts; lithium carbonate, lithium bromide, lithium chloride Inorganic lithium salts such as lithium fluoride, lithium hydroxide, lithium nitrate, and lithium sulfate can be used, and one or more of these can be used. Among these, lithium acetate and lithium oxalate, which are organic acid lithium having a melting point of 400 ° C. or lower, are preferable. In addition, a method in which a non-organic acid lithium salt such as lithium carbonate and an organic acid such as acetic acid are mixed and used as a lithium organic acid salt is also a suitable technique.

The amount of the lithium salt used is preferably 0.5 to 1.5 equivalents relative to the equivalent of the precursor core component. When the amount is less than 0.5 equivalent, the precursor core component cannot be made into an electrode active material sufficiently. When the amount is more than 1.5 equivalent, lithium becomes excessive with respect to the electrode active material. The structure may change. The amount of the lithium salt used is more preferably 0.7 to 1.2 equivalents, still more preferably 0.9 to 1.1 equivalents, relative to the equivalent of the precursor core component.

The other material preferably further contains a hydrocarbon component. When the hydrocarbon component is included, it is possible to suppress the crystal growth of the electrode active material fine particles obtained by firing, thereby making it possible to produce uniform active material fine particles having a smaller particle diameter, and more An electrode material having excellent performance can be manufactured. In addition, since the hydrocarbon component is carbonized at the time of firing to form a coating structure on the electrode active material fine particles, the amount of the oxidatively polymerizable monomer used in the synthesis step can be reduced by using the hydrocarbon component.
Further, for example, in the process of synthesizing the electrode active material, such as when producing an electrode active material having lithium iron phosphate as the electrode active material core using iron (III) chloride as the oxidizing agent, When the metal component is reduced, in the firing step, the polymer that forms the hydrocarbon coating structure on the precursor fine particles acts as a reducing agent to reduce the metal component, and the electrode active material is generated in the firing step. Although it will be accelerated | stimulated, the production | generation of the electrode active material in a baking process can be promoted more by including a hydrocarbon component further.
As described above, a method for producing an electrode active material by mixing the precursor obtained by the method for producing an electrode material precursor of the present invention and a hydrocarbon component is also one of the preferred embodiments of the present invention. is there.

Examples of the hydrocarbon component include sugars such as sucrose, glucose, fructose, trehalose, lactose, maltose, galactose, mannose, and agarose; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polystyrene Water-soluble polymers such as sulfonic acid, polyacrylamide and polyvinyl acetate and their derivatives; cellulose such as starch, cellulose, gelatin, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose and their derivatives; polyethylene, polypropylene, polybutadiene, poly Polyolefins such as isoprene, polystyrene, (meth) acrylic resin; May be used alone or two or more of such Lumpur resin. Among these, sugars such as sucrose, glucose, fructose, maltose, and water-soluble polymers such as polyvinyl alcohol are preferable. More preferably, it is sucrose.

The amount of the hydrocarbon component used is preferably 1 to 50% by mass with respect to 100% by mass of the precursor core component. If the amount of the hydrocarbon component used is less than 1% by mass, the effect of suppressing the crystal growth of the electrode active material fine particles cannot be sufficiently obtained. If the amount used exceeds 50% by mass, the proportion of the component acting as an electrode is small. Therefore, the performance as an electrode material may be reduced. More preferably, it is 3 to 40% by mass, and further preferably 5 to 30% by mass with respect to 100% by mass of the precursor core component.

The method of mixing the precursor powder after drying and other materials including lithium salt and the like is not particularly limited, and the powder may be mixed as it is, but is preferably mixed in the presence of a solvent. Mixing in the presence of a solvent to paste the mixture, and firing the resulting mixture to produce an electrode active material, mix evenly compared to using a dry-mixed mixture of powder As a result, the obtained active material fine particles become homogeneous, and the electrode active material having such active material fine particles exhibits high performance as an electrode material.
Such a method for producing an electrode active material by mixing a precursor obtained by the method for producing an electrode material precursor of the present invention with another material containing a lithium salt in the presence of a solvent is also included in the present invention. This is one of the preferred embodiments.
The step of mixing the precursor and another material containing a lithium salt is preferably a step of pulverizing and mixing the precursor powder in order to increase the contact ratio between these materials.

The solvent is preferably one or more of water, water-soluble alcohols such as methanol and ethanol, aprotic polar solvents such as dimethyl sulfoxide, N, N-dimethylformamide, acetonitrile and hexamethylphosphoric triamide. . More preferably, it is water. In particular, when lithium acetate is used as the lithium salt, the solvent is most preferably water.
Thus, a method for producing an electrode active material using water and / or an aqueous solvent as a solvent is also one of the preferred embodiments of the present invention.

The amount of the solvent used may be 5 to 100% by mass with respect to 100% by mass in total including the hydrocarbon component when the precursor powder, the lithium salt, and the hydrocarbon component are used. preferable. If the amount of the solvent used is less than 5% by mass, the mixture cannot be made into a paste, and if it is more than 100% by mass, the mixed state may become uneven when the solvent evaporates from the mixture. More preferably, when the precursor powder, the lithium salt, and the hydrocarbon component are used, the amount is 10 to 80% by mass, more preferably 15% with respect to 100% by mass in total including the hydrocarbon component. -70% by mass.

The firing temperature is preferably 200 to 1000 ° C. More preferably, it is 400 to 800 ° C.
The firing time is preferably 0.5 to 24 hours. More preferably, it is 1 to 18 hours.
Further, the baking process may be performed in multiple stages at different temperatures, and baking is performed at 200 to 500 ° C. for 0.5 to 12 hours, and then baking is performed at 500 to 800 ° C. for 0.5 to 12 hours. Is preferred.
The firing is preferably performed in a reducing atmosphere such as hydrogen or carbon monoxide, or in an inert gas atmosphere such as nitrogen, argon, or helium.

Fine particles of the electrode active material having a uniform particle diameter can be obtained by pulverizing the fired body obtained by the firing step in a dry manner and sieving it into a particle powder having a desired size.
The average primary particle size of the electrode active material is preferably 5 to 1000 nm. By using an electrode active material having an average primary particle size of 5 to 1000 nm as the electrode material, it is possible to improve electrical characteristics such as output characteristics of the battery. The average primary particle size is more preferably 10 to 800 nm, still more preferably 20 to 500 nm.
The average primary particle diameter of the fine particles of the electrode active material is represented by the average of the primary particle diameters of 100 particles observed with a transmission electron microscope (TEM).
The fine particles of the electrode active material mean fine particles of the entire electrode active material including not only the electrode active material core but also the shell portion.
The crystallite diameter of the electrode active material core is preferably 5 to 1000 nm, more preferably 10 to 800 nm, and still more preferably 20 to 500 nm.
The crystallite diameter of the electrode active material core can be measured by X-ray diffraction.

The electrode active material (electrode material) preferably contains a compound having an olivine structure. The compound having an olivine structure is the following formula (1);
LiMPO ₄ (1)
(M is a compound having a structure represented by one or more transition metals). In such an electrode active material, (PO ₄ ) ^3- polyanion is formed by bonding oxygen atoms in the structure with phosphorus, and in principle, the oxygen is immobilized in the crystal structure. This is particularly preferable as an electrode material used for medium and large-sized power supplies. This electrode material can be suitably used as an electrode for various batteries, and can also be suitably used for a battery using a nonaqueous solvent as a solvent for dissolving an electrolyte.
Such a lithium-containing electrode material containing a compound having an olivine structure represented by the above formula (1) and a nonaqueous electrolyte battery using the lithium-containing electrode material are also one aspect of the present invention.

In the above formula (1), M is preferably one or more metals selected from Fe, Mn, Co, and Ni. More preferably, it is Fe and / or Mn.
Further, a small amount of metal species may be contained in order to increase the conductivity of the compound having an olivine structure, or to improve battery characteristics such as high-speed charge / discharge performance and cycle characteristics. Examples of the metal species include Cu, Ce, Cr, Mo, Nb, Mg, Ca, Sr, Ba, Ti, V, Zn, B, Al, Ga, In, Si, Ge, Sc, Y, and rare earth elements. . A small amount means 10 mass% or less with respect to M100 mass%.

As described above, the method for producing an electrode material precursor according to the present invention has a sufficiently high performance of the obtained electrode material (electrode active material) even when a high-concentration reaction material is used. In addition, since the active material raw material is used in a state of being dissolved in a solvent, the active material raw material in the reaction solution aggregates and grows to increase the particle size. The electrode material precursor obtained in this way is an electrode material that exhibits excellent characteristics. It can be suitably used as a material.
And the manufacturing method of the lithium-containing electrode material of the present invention can react in a more uniformly mixed state when reacting the electrode material precursor and other material containing a lithium salt, A method capable of producing a lithium-containing electrode material that is more homogeneous than before, and the electrode active material thus obtained can be suitably used as a lithium-containing electrode material that exhibits excellent characteristics. It is.
Thus, the electrode material precursor obtained by the method for producing an electrode material precursor of the present invention is also one aspect of the present invention.
Furthermore, an electrode material obtained by using the electrode material precursor obtained by such a method for producing an electrode material precursor of the present invention is also one aspect of the present invention.
The lithium-containing electrode material obtained by the method for producing a lithium-containing electrode material of the present invention is also one aspect of the present invention.
Such (lithium-containing) electrode material can be suitably used as an electrode for various batteries, and can also be suitably used for a battery using a nonaqueous solvent as a solvent for dissolving an electrolyte.
Such a nonaqueous electrolyte battery using the (lithium-containing) electrode material of the present invention is also one aspect of the present invention.

As the method for producing the electrode material of the present invention, it is preferable to employ the above-described method for producing the electrode material precursor of the present invention and the method for producing the lithium-containing electrode material of the present invention. It is preferable to have the same structure as the electrode material manufactured by the manufacturing method of the electrode material precursor of this invention and the manufacturing method of the lithium containing electrode material of this invention.

When the method for producing a lithium-containing electrode material according to the above-described method for producing an electrode material precursor of the present invention and the method for producing a lithium-containing electrode material of the present invention is adopted as a method for producing the electrode material of the present invention, the precursor It is preferable that the material to be mixed with contains a hydrocarbon component. As described above, the hydrocarbon component also forms a coating structure on the active material fine particles at the time of firing. Use of a material having a nitrogen atom therein can contribute to increasing the nitrogen atom content of the active material. That is, it is also one of preferred embodiments of the present invention to use a hydrocarbon component having a nitrogen atom in the structure.
As the hydrocarbon component having a nitrogen atom in the structure, the same as the polymer having a nitrogen atom described above can be used.

It is also one of preferred embodiments of the present invention to use a material containing an ammonium salt together with a hydrocarbon component as a material to be mixed with the precursor. That is, at the time of firing, the hydrocarbon component is carbonized to form a coating structure on the active material fine particles, and at the same time, by incorporating an ammonium salt into the coating structure, the nitrogen atom content of the active material can be increased.
The type of ammonium salt that can be used for mixing with the precursor is not particularly limited, but examples thereof include inorganic ammonium salts such as ammonium chloride, ammonium carbonate, ammonium sulfate, ammonium nitrate, and ammonium phosphate; ammonium acetate, ammonium oxalate. And organic acid ammonium salts such as ammonium citrate. In addition, salt compounds of these organic acids with nitrogen-containing cations such as primary to quaternary ammonium cations, imidazolium cations, imidazolinium cations, piperidinium cations, pyrrolidinium cations can be exemplified. Using one or more of these is also one preferred embodiment of the present invention.

The amount of the ammonium salt used is preferably 0.1 to 100% by mass with respect to 100% by mass of the hydrocarbon component. Use of an ammonium salt in such a range can contribute to increasing the nitrogen atom content of the active material without hindering the crystal growth of the active material fine particles. More preferably, it is 0.5 to 50% by mass, and further preferably 1 to 30% by mass with respect to 100% by mass of the hydrocarbon component used.

When the method for producing a lithium-containing electrode material according to the above-described method for producing an electrode material precursor of the present invention and the method for producing a lithium-containing electrode material of the present invention is adopted as a method for producing the electrode material of the present invention, oxidation polymerization is performed. Although what was mentioned above is used as a property monomer, it is preferable that it has a nitrogen atom in a structure. Examples of the polymer (conductive carbon material precursor) obtained by polymerizing such an oxidatively polymerizable monomer include polyaniline, polypyrrole, and polyvinylcarbazole. More preferred are polyaniline and polypyrrole, and most preferred is polyaniline. Moreover, it is preferable that the nitrogen atom content rate of the polymer obtained by superposing | polymerizing these oxidatively polymerizable monomers is 10 weight% or more. If it is less than 10% by weight, the nitrogen atom content contained in the active material is reduced, and it is difficult to contribute to the improvement of water dispersibility. More preferably, it is 12% by weight or more.
Thus, it is also one of the preferred embodiments of the present invention that the conductive carbon material precursor has a nitrogen atom in the structure.
In addition, the method for producing the lithium-containing electrode material by the above-described method for producing the electrode material precursor of the present invention and the method for producing the lithium-containing electrode material of the present invention is adopted, and the structure such as phenol is used as the oxidative polymerizable monomer. When using a material that does not have a nitrogen atom, as described above, by polymerizing or polycondensing a monomer having a nitrogen atom on the surface of the obtained active material precursor or active material (electrode active material), An active material in which a coating structure is formed by a nitrogen-containing polymer to be produced is manufactured, and an active material having a structure covered with a conductive carbon material is manufactured by heat treatment, and the obtained active material precursor or active material is obtained. (Electrode active material) is immersed in a polymer solution containing nitrogen atoms and dried to polymer coat the active material precursor or active material, and then heat treatment. By producing an active material having a structure coated with a conductive carbon material, the active material has a structure coated with a conductive carbon material, and the nitrogen atom content is 100% by mass relative to the total amount of the active material. An electrode material of 0.3% by mass or more can be produced.

All the methods for producing the electrode material of the present invention described above perform a heat treatment step, but the heat treatment step is performed under a reducing atmosphere such as hydrogen or carbon monoxide, or nitrogen, argon, helium or the like. It is preferably performed in an inert gas atmosphere. Among these, it is particularly preferable that the reaction be performed in a nitrogen atmosphere. By performing the heat treatment step in a nitrogen atmosphere, the nitrogen content of the active material can be increased.
That is, it is also one of preferred embodiments of the present invention that the structure covered with the conductive carbon material is formed by firing the conductive carbon material precursor in a nitrogen atmosphere.

The method for producing an electrode using the electrode material of the present invention is not particularly limited, and can be produced by a usual production method. As a general method for producing an electrode, components constituting an electrode to be produced, such as an electrode material, a conductive auxiliary agent, a binder, and a dispersing agent, are added to a solvent, kneaded to form a slurry, and then the obtained slurry Is applied to a current collector, and dried to remove the solvent, thereby forming a film-like electrode. Thus, the electrode formed using the electrode material of the present invention can be suitably used as an electrode of various batteries, and such an electrode containing the electrode material of the present invention is also one of the present invention. One. Furthermore, a battery using the electrode of the present invention is also one aspect of the present invention.

As long as the electrode of this invention contains the electrode material of this invention, the other component normally contained in an electrode may be included. Examples of other components usually contained in the electrode include a conductive additive, a binder, a dispersant, and a thickener.

The conductive aid is appropriately used to increase the output of the battery, and conductive carbon is mainly used.
Examples of the conductive carbon include carbon black, fiber-like carbon, and graphite. As the conductive assistant, one or more of these can be used.

Although what is normally used as a binder can be used as said binder, It is preferable to use an emulsion. For example, fluorine-containing polymers such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyhexafluoroethylene, and emulsions of (meth) acrylic modified products thereof, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR) and the like Examples include nitrile emulsions such as hydrogenated products (HNBR), (meth) acrylic emulsions, and the like. As the binder, one or more of these can be used.

Examples of the thickener include celluloses such as carboxymethylcellulose (CMC), methylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, hydroxypropylmethylcellulose, and hydroxyethylmethylcellulose; polycarboxylic acid compounds such as polyacrylic acid and sodium polyacrylate; polyvinyl Examples thereof include water-soluble polymers such as compounds having a vinylpyrrolidone structure such as pyrrolidone; polyalkylene oxides; As a thickener, these 1 type (s) or 2 or more types can be used.

The electrode preferably uses a dispersant. When an active material having a nitrogen atom content of 0.3% by mass or more based on 100% by mass of the total amount of active materials is used as the active material, the active material is highly dispersible in water. Even if the amount of use is reduced, it can be dispersed in an aqueous solvent, but even in that case, the water dispersibility of the active material can be further enhanced by further using a dispersant.
As the dispersant, those usually used as a dispersant can be used, and are not particularly limited, but various dispersants such as anionic, nonionic or cationic surfactants or polymer dispersants can be used. Can be used. By promoting the formation of fine particles of the active material and the conductive aid and improving the dispersibility by the dispersant, it becomes possible to obtain a more stable and high-performance electrode.
As a dispersing agent, these 1 type (s) or 2 or more types can be used.

The solvent used when slurrying the components constituting the electrode is preferably an aqueous solvent. By using an aqueous solvent as a solvent, it is safer than when N-methylpyrrolidone (NMP) is used as a solvent, and when NMP is used, NMP must be recovered after use. Since a recovery cost is required, the cost performance is better when an aqueous solvent is used.
The aqueous solvent is a solvent containing water, and may contain other components as long as it contains water.

Since the electrode material of the present invention has the above-described configuration and the water dispersibility of the active material contained in the electrode material is high, an aqueous slurry in which the active material is dispersed can be prepared. Even when the electrode is formed, it is possible to form an electrode excellent in battery performance. In addition, the method for producing an electrode material precursor of the present invention has the above-described configuration, and even when the reaction raw material is made high in concentration by controlling the pH of the reaction solution within a specific range, the performance as an electrode material is improved. The precursor of the electrode material can be produced while sufficiently suppressing the decrease. Moreover, since the active material material is used in a state dissolved in a solvent, the active material material in the reaction solution is prevented from agglomerating and growing to increase the particle size, and the particle size is small and uniform. It is a manufacturing method which can manufacture a precursor. Alternatively, by performing the reaction while supplying the active material raw material and / or the oxidative polymerizable monomer into the reaction solution in addition to the oxidizing agent, the performance as an electrode material can be improved even when the concentration of the reactive raw material is high. The precursor of the electrode material can be produced while sufficiently suppressing the decrease. From these things, it can use suitably as a manufacturing method of the precursor of the electrode material used for the battery which exhibits the outstanding battery performance. Furthermore, the method for producing a lithium-containing electrode material according to the present invention has the above-described configuration, and reacts the electrode material precursor with another material containing a lithium salt in a more uniformly mixed state. Since this enables production of a lithium-containing electrode material that is more homogeneous than before, it can be suitably used as a method for producing a lithium-containing electrode material used in a battery that exhibits excellent battery performance. It is.

A precursor is synthesized using the method for producing an electrode material precursor of the present invention, and a lithium-containing electrode material (electrode active material) is synthesized from the obtained precursor using the method for producing a lithium-containing electrode material of the present invention. As an example of the flow, an electrode material precursor synthesized while adding an oxidizing agent and an oxidative polymerizable monomer dropwise is used, and the electrode material precursor, lithium salt and hydrocarbon component are wet-mixed in the presence of a solvent and baked. FIG. 5 is a diagram showing a flow when a lithium-containing electrode material (electrode active material) having a core-shell structure is synthesized.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

Various measurements and evaluations in the examples were performed as follows.
[Nitrogen atom content of active material]
The content of nitrogen atoms contained in the active material was measured under the following measurement conditions using the following apparatus.
Apparatus: Nitrogen and oxygen simultaneous analyzer TC400 (product name, manufactured by LECO)
Measurement conditions Carrier gas; He
Detection method; thermal conductivity method sample amount; 20 to 30 mg
Capsule made of Ni

[Water dispersibility]
20 g of ion-exchanged water was added to 0.5 g of the electrode material and permeated by hand for 20 seconds to disperse the active material in the site. After a predetermined time, the dispersibility was judged visually.
Evaluation criteria (circle): Settling of particle | grains was not confirmed after leaving still for 5 minutes.
Δ: Settling of particles was confirmed after standing for 5 minutes.
X: After settling for 1 minute, sedimentation of particles was confirmed.

[Contact angle]
The contact angle of the active material with respect to water was measured by the following apparatus and measurement conditions, and evaluated according to the following evaluation criteria.
Apparatus: Contact angle meter DCA-VZ (trade name, manufactured by Kyowa Interface Science Co., Ltd.)
Measurement conditions: 2 g of electrode material is sandwiched between stainless steel plates, and a pressure of 10 t is applied with a press machine and held for 1 minute. A 2 μl droplet is dropped on the obtained sample, and measurement is performed immediately after the dropping. The measurement is performed 5 times each, and the average value thereof is defined as the contact angle.
Evaluation criteria:
○: Droplet does not penetrate into sample and cannot be measured.
△ ・ ・ ・ 0 ° <Contact angle ≦ 30 °
× ・ ・ ・ 30 ° <Contact angle

[Charge / discharge test]
Using a charge / discharge measuring apparatus ACD-001 (manufactured by Asuka Electronics Co., Ltd.), the capacity was measured, and the battery was evaluated using a coin cell battery.
Positive electrode: A water-based slurry was prepared using a positive electrode active material, SBR, and CMC, and an electrode material was applied on an aluminum foil using an applicator. The film was dried at 100 ° C. for 10 minutes, then at 200 ° C. for 60 minutes, and further subjected to hot pressing at 200 ° C. for 30 minutes to produce a film having a thickness of about 100 μm. The obtained film was used as a positive electrode.
Negative electrode: Li foil electrolyte: 1 mol / L LiPF ₆ EC / EMC = 1/1 (manufactured by Kishida Chemical Co., Ltd.)
Charge / discharge rate: 0.2C

(Preparation Example 1)
A 2 L separable flask was charged with 637.5 ml of water and heated to 50 ° C. with stirring. Next, in a state where stirring was maintained while maintaining the temperature at 50 ° C., 511.16 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the above separable flask. At the same time as addition of an aqueous solution dissolved in 4 ml of water was started, addition of an aqueous solution obtained by dissolving 249.23 g of diammonium hydrogen phosphate (manufactured by Kanto Chemical Co., Ltd.) in 414.0 ml of water and aniline (manufactured by Kishida Chemical Co., Ltd.) The addition of 84.95 g was started. The time from the start to the end of the addition of the aqueous solution of iron (III) chloride is 31 minutes, the time from the start to the end of the addition of the diammonium hydrogen phosphate aqueous solution is 30 minutes, and the time from the start to the end of the addition of aniline is It was 47 minutes. After the addition of aniline, stirring was continued at 50 ° C. for 2 hours.
The liquid after completion of the stirring was centrifuged to remove the supernatant, and water was added to the resulting precipitate (paste) for redispersion, followed by washing again by centrifugation. The precipitate obtained after the washing operation is dried under reduced pressure at 50 ° C. for 15 hours, whereby an electrode material precursor (average particle diameter is 100 nm or less and FePO ₄ (core) is coated with polyaniline (shell) ( 1) was obtained.

Example 1
The electrode material precursor (1) obtained in Preparation Example 1 was put in a mortar, and 46 parts by mass of CH ₃ COOLi, 49 parts by mass of 100 parts by mass of FePO ₄ contained in the electrode material precursor (1). Sucrose and an appropriate amount of water were added and mixed to homogenize. Next, the mixture was dried at 50 ° C. under reduced pressure, and then placed in a firing furnace. The temperature was raised from room temperature to 400 ° C. over 40 minutes while flowing nitrogen through the firing furnace. After the temperature reached 400 ° C., it was maintained for 3 hours to remove water and volatile organic substances. Subsequently, the temperature was raised from 400 ° C. to 700 ° C. in 30 minutes. Furthermore, after the temperature reached 700 ° C., it was held for 5 hours, and then cooled to room temperature to obtain an electrode material (1) having a core / shell structure in which the active material core was LiFePO ₄ and was coated with carbon. . The nitrogen atom content of the electrode material (1) was 0.62% by mass. Moreover, about the obtained electrode material (1), the water dispersibility, a contact angle, and battery performance were evaluated. The results are shown in Table 1.

(Examples 2 to 4)
In Example 1, the amount of sucrose added to the electrode material precursor (1) was 25 parts by mass, 16 parts by mass, and 10 parts by mass with respect to 100 parts by mass of FePO ₄ contained in the electrode material precursor (1). Except for the above, electrode materials (2) to (4) were obtained in the same manner as in Example 1. The nitrogen atom content of the electrode material (2) is 0.60 mass%, the nitrogen atom content of the electrode material (3) is 0.58 mass%, and the nitrogen atom content of the electrode material (4) is 0. It was 49% by mass. Further, the performance of the electrode materials (2) to (4) was evaluated in the same manner as the electrode material (1). The results are shown in Table 1.

(Comparative Example 1)
According to Japanese Patent Application Laid-Open No. 2010-40357, a reference electrode material (1) having a core / shell structure in which the active material core is LiFePO ₄ and coated with carbon was obtained. The nitrogen atom content of the electrode material (Comparative 1) was 0.24% by mass. Moreover, the performance of the electrode material (Comparative 1) was evaluated in the same manner as the electrode material (1). The results are shown in Table 1.

(Comparative Example 2)
Evaluation was performed using a commercially available lithium iron phosphate (lithium iron phosphate SLFP-PD60 manufactured by Tianjin STL ENERGY TECHNOLOGY). The nitrogen atom content was 0.17% by mass. Moreover, the performance was evaluated similarly to the electrode material (1). The results are shown in Table 1.

The following was found from the results of Examples 1 to 4 and Comparative Examples 1 and 2.
The active material has a structure coated with a conductive carbon material, and the content of nitrogen atoms contained in the active material is 0.3% by mass or more with respect to 100% by mass of the total amount of the active material. It has been demonstrated that an electrode material containing such an active material has excellent water dispersibility and can form an electrode having excellent battery performance.
In the above embodiment, lithium iron phosphate covered with carbon and having a core / shell structure is used as the active material, but the active material is covered with a conductive carbon material, By making the content of nitrogen atoms contained in the active material into a specific range, an electrode material containing such an active material becomes excellent in water dispersibility and forms an electrode excellent in battery performance. The mechanism that can be used is the same in the case of using an active material having a structure covered with a conductive carbon material and containing a specific amount of nitrogen atoms. Therefore, it can be said from the results of the above-described embodiments that the present invention can be applied in the entire technical scope of the present invention and in various forms disclosed in this specification, and can exhibit advantageous effects.

The average primary particle diameter of the electrode material precursor and the crystallite diameter of the electrode active material core in the following examples were measured as follows.
[Average primary particle size of electrode material precursor]
The average primary particle diameter of 100 particles observed with a transmission electron microscope (TEM) was used.
[Crystal diameter of electrode active material core]
Measurement was performed by X-ray diffraction using an X-ray diffractometer (X'pert Pro MPD system, Spectris Co., Ltd.).

(Preparation Example 2)
A 3 l separable flask was charged with 18.34 g of ammonium dihydrogen phosphate (manufactured by Kanto Chemical Co., Inc.), 7.14 g of aniline (manufactured by Kishida Chemical Co., Ltd., purity 99.5% or more) and 1400 ml of water, and stirred at room temperature. Mixed. Next, in a state where stirring is maintained, an aqueous solution in which 43.10 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in 700 ml of water is placed in the separable flask over 30 minutes. Further, stirring was continued at room temperature for 5 hours. At this time, the concentration of the essential raw material with respect to 100% by mass of the solution containing all the precursor raw materials was 3.2% by mass. After completion of the stirring, the pH of the reaction solution was 1.47.
The liquid after completion of the stirring was centrifuged to remove the supernatant, and water was added to the resulting precipitate (paste) for redispersion, followed by washing again by centrifugation. The precipitate obtained after the washing operation is dried under reduced pressure at 50 ° C. for 15 hours, whereby an electrode material precursor (average particle diameter is 100 nm or less and FePO ₄ (core) is coated with polyaniline (shell) ( 2) was obtained.

(Example 5)
Put the electrode material precursor obtained in Preparation Example 2 (2) in a mortar, 36 wt relative FePO ₄ of FePO ₄ and equimolar _CH 3 COOLi, 100 parts by weight contained in the electrode material precursor (2) A portion of sucrose and an appropriate amount of water were added and mixed to homogenize. Next, the mixture was dried at 50 ° C. under reduced pressure, and then placed in a firing furnace. The temperature was raised from room temperature to 400 ° C. over 40 minutes while flowing nitrogen through the firing furnace. After the temperature reached 400 ° C., it was maintained for 3 hours to remove water and volatile organic substances. Subsequently, the temperature was raised from 400 ° C. to 700 ° C. in 30 minutes. Furthermore, after the temperature reached 700 ° C., it was held for 5 hours, and then cooled to room temperature to obtain an electrode material (5) having a core / shell structure in which the active material core was LiFePO ₄ and was coated with carbon. . The nitrogen atom content of the electrode material (5) was 0.31% by mass. The crystallite diameter of the core (LiFePO ₄ ) of the electrode material (5) measured by X-ray diffraction was 56 nm.

(Preparation Example 3)
In a 3 l separable flask, diammonium hydrogen phosphate (manufactured by Kanto Chemical Co., Inc.) 5.26 g, triammonium phosphate trihydrate (manufactured by Kishida Chemical Co., Ltd.) 24.29 g, aniline (manufactured by Kishida Chemical Co., Ltd., purity) (99.5% or more) 7.14 g and 1400 ml of water were charged and stirred and mixed at room temperature. Next, in a state where stirring is maintained, an aqueous solution in which 43.10 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in 700 ml of water is placed in the separable flask over 30 minutes. Further, stirring was continued at room temperature for 5 hours. At this time, the concentration of the essential raw material with respect to 100% by mass of the solution containing all the precursor raw materials was 3.7% by mass. After completion of the stirring, the pH of the reaction solution was 3.31.
The liquid after completion of the stirring was centrifuged to remove the supernatant, and water was added to the resulting precipitate (paste) for redispersion, followed by washing again by centrifugation. The precipitate obtained after the washing operation is dried under reduced pressure at 50 ° C. for 15 hours, whereby an electrode material precursor (3) in which the average particle size is 100 nm or less and FePO 4 (core) is coated with polyaniline (shell). )

(Example 6)
The electrode material precursor (3) obtained in Preparation Example 3 is put in a mortar, and 36 masses with respect to FePO ₄ and equimolar CH ₃ COOLi contained in the electrode material precursor (3), 100 parts by mass of FePO ₄ . A portion of sucrose and an appropriate amount of water were added and mixed to homogenize. Next, the mixture was dried at 50 ° C. under reduced pressure, and then placed in a firing furnace. The temperature was raised from room temperature to 400 ° C. over 40 minutes while flowing nitrogen through the firing furnace. After the temperature reached 400 ° C., it was maintained for 3 hours to remove water and volatile organic substances. Subsequently, the temperature was raised from 400 ° C. to 700 ° C. in 30 minutes. Furthermore, after the temperature reached 700 ° C., it was held for 5 hours, and then cooled to room temperature to obtain an electrode material (6) having a core / shell structure in which the active material core was LiFePO ₄ and was coated with carbon. . The nitrogen atom content of the electrode material (6) was 0.33% by mass. The crystallite diameter of the core (LiFePO ₄ ) of the electrode material (6) measured by X-ray diffraction was 587 nm.

(Preparation Example 4)
In a 500 ml separable flask, 30.10 g of diammonium hydrogen phosphate (manufactured by Kanto Chemical Co., Ltd.), 15.30 g of aniline (manufactured by Kishida Chemical Co., Ltd., purity 99.5% or more), N, N-dimethylformamide (Kanto Chemical Co., Ltd.) (Made by Co., Ltd., purity 99.5% or more) 21 ml and water 200 ml were charged and stirred and mixed at room temperature. Next, in a state where stirring is maintained, an aqueous solution in which 61.61 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in 100 ml of water is placed in the separable flask over 30 minutes. Further, stirring was continued at room temperature for 5 hours. At this time, the concentration of the essential raw material with respect to 100% by mass of the solution containing all the precursor raw materials was 25.0% by mass. After the completion of stirring, the pH of the reaction solution was 1.53.
The liquid after completion of the stirring was centrifuged to remove the supernatant, and water was added to the resulting precipitate (paste) for redispersion, followed by washing again by centrifugation. The precipitate obtained after the washing operation is dried under reduced pressure at 50 ° C. for 15 hours, whereby an electrode material precursor (average particle diameter is 100 nm or less and FePO ₄ (core) is coated with polyaniline (shell) ( 4) was obtained.

(Example 7)
Put Preparation Example 4 in the obtained electrode material precursor (4) in a mortar, the electrode material precursor (4) equimolar with FePO ₄ included in _CH 3 COOLi, 100 parts by 36 weight relative FePO ₄ of A portion of sucrose and an appropriate amount of water were added and mixed to homogenize. Next, the mixture was dried at 50 ° C. under reduced pressure, and then placed in a firing furnace. The temperature was raised from room temperature to 400 ° C. over 40 minutes while flowing nitrogen through the firing furnace. After the temperature reached 400 ° C., it was maintained for 3 hours to remove water and volatile organic substances. Subsequently, the temperature was raised from 400 ° C. to 700 ° C. in 30 minutes. Furthermore, after the temperature reached 700 ° C., it was held for 5 hours, and then cooled to room temperature to obtain an electrode material (7) having a core / shell structure in which the active material core was LiFePO ₄ and was coated with carbon. . The nitrogen atom content of the electrode material (7) was 0.52% by mass. The crystallite diameter of the core (LiFePO ₄ ) of the electrode material (7) measured by X-ray diffraction was 69 nm.

(Preparation Example 5)
In a 500 ml separable flask, triammonium phosphate trihydrate (Kishida Chemical Co., Ltd.) 46.29 g, aniline (Kishida Chemical Co., Ltd., purity 99.5% or more) 15.30 g, N, N-dimethylformamide (Kanto Chemical Co., Inc., purity 99.5% or more) 21 ml and water 200 ml were charged and stirred and mixed at room temperature. Next, in a state where stirring is maintained, an aqueous solution in which 61.61 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in 100 ml of water is placed in the separable flask over 30 minutes. Further, stirring was continued at room temperature for 5 hours. At this time, the concentration of the essential raw material with respect to 100% by mass of the solution containing all the precursor raw materials was 27.7% by mass. After completion of the stirring, the pH of the reaction solution was 3.12.
The liquid after completion of the stirring was centrifuged to remove the supernatant, and water was added to the resulting precipitate (paste) for redispersion, followed by washing again by centrifugation. The precipitate obtained after the washing operation is dried under reduced pressure at 50 ° C. for 15 hours, whereby an electrode material precursor (average particle size is 100 nm or less and FePO ₄ (core) is coated with polyaniline (shell) ( 5) was obtained.

(Example 8)
The electrode material precursor (5) obtained in Preparation Example 5 is put in a mortar, and 36 masses with respect to FePO ₄ and equimolar CH ₃ COOLi contained in the electrode material precursor (5), 100 parts by mass of FePO ₄ . A portion of sucrose and an appropriate amount of water were added and mixed to homogenize. Next, the mixture was dried at 50 ° C. under reduced pressure, and then placed in a firing furnace. The temperature was raised from room temperature to 400 ° C. over 40 minutes while flowing nitrogen through the firing furnace. After the temperature reached 400 ° C., it was maintained for 3 hours to remove water and volatile organic substances. Subsequently, the temperature was raised from 400 ° C. to 700 ° C. in 30 minutes. Furthermore, after the temperature reached 700 ° C., it was held for 5 hours, and then cooled to room temperature to obtain an electrode material (8) having a core-shell structure in which the active material core was LiFePO ₄ and was coated with carbon. . The nitrogen atom content of the electrode material (8) was 0.60% by mass. The crystallite diameter of the core (LiFePO ₄ ) of the electrode material (8) measured by X-ray diffraction was 355 nm.

(Creation of positive electrode film)
A positive electrode composition (5) was obtained by mixing PVdF as a binder, a conductive additive, N-methyl-2-pyrrolidinone as a solvent, and the electrode material (5) obtained above. The obtained positive electrode composition was coated on an aluminum foil to prepare a positive electrode film (5).
Also, positive electrode compositions (6) to (8) were prepared in the same manner as described above except that the electrode materials (6) to (8) were used instead of the electrode material (5), respectively. ) To (8) were produced.

(Charge / discharge test)
The produced positive electrode films (5) to (8) were subjected to battery evaluation of a coin cell (CR2032) using a charge / discharge measuring apparatus ACD-001 (manufactured by Asuka Electronics Co., Ltd.). The results are shown in Table 2.
Positive electrode: prepared positive electrode film Negative electrode: Li foil electrolyte: 1 mol% / L LiPF ₆ EC / EMC = 1/1 (manufactured by Kishida Chemical Co., Ltd.)
Separator: Porous polypropylene membrane charge / discharge condition: 0.2C
Cut-off voltage: 2.0-4.0V
Evaluation temperature: 30 ° C

From the results shown in Table 2, the positive electrode film produced using the electrode materials (5) and (7) is more positive than the positive electrode film produced using the electrode materials (6) and (8). The electrode material precursor of the present invention is produced by adjusting the pH of the solution to 0.3 or more and 3.0 or less when all the essential raw materials are mixed. It was confirmed that the precursor obtained by the method can be more suitably used as an electrode material exhibiting excellent performance.

(Preparation Example 6)
A 500 ml separable flask was charged with 48.16 g of diammonium hydrogen phosphate (manufactured by Kanto Chemical Co., Inc.), 40 ml of N, N-dimethylformamide (manufactured by Kanto Chemical Co., Ltd., purity 99.5% or more) and 160 ml of water. Stir and mix at ° C. Next, in a state where stirring was maintained while maintaining the temperature at 40 ° C., 98.58 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 80 ml of the above separable flask. The addition of an aqueous solution dissolved in water was started. From the time when ½ of the total volume of the aqueous iron (III) chloride solution is added, the addition of the aqueous iron (III) chloride solution is continued, and aniline (manufactured by Kishida Chemical Co., Ltd., purity 99.5% or more). The addition of 41 g was started. The time from the start to the end of the addition of the aqueous iron (III) chloride solution was 60 minutes, and the time from the start to the end of the aniline addition was 20 minutes. After the addition of the aqueous iron (III) chloride solution was completed, stirring was continued at 40 ° C. for 5 hours. At this time, the concentration of the essential raw material with respect to 100% by mass of the solution containing all the precursor raw materials was 36.8% by mass.
The liquid after completion of the stirring was centrifuged to remove the supernatant, and water was added to the resulting precipitate (paste) for redispersion, followed by washing again by centrifugation. The precipitate obtained after the washing operation is dried under reduced pressure at 50 ° C. for 15 hours, whereby an electrode material precursor (average particle size is 100 nm or less and FePO ₄ (core) is coated with polyaniline (shell) ( 6) was obtained.

(Preparation Example 7)
In a 500 ml separable flask, 24.62 g of aniline (manufactured by Kishida Chemical Co., Ltd., purity 99.5% or more) and 60 ml of water were charged and stirred and mixed at 50 ° C. Next, in a state where stirring was maintained while maintaining the temperature at 50 ° C., 147.87 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 80 ml of the above separable flask. At the same time as the addition of the aqueous solution dissolved in water was started, 36 ml of diammonium hydrogen phosphate (manufactured by Kanto Chemical Co., Ltd.) and 55.56 g of triammonium phosphate trihydrate (manufactured by Kishida Chemical Co., Ltd.) were added to 120 ml of water. The addition of the aqueous solution dissolved in was started. The time from the start to the end of the addition of the aqueous iron (III) chloride solution was 60 minutes, and the time from the start to the end of the addition of the aqueous phosphate solution was 40 minutes. After completion of the addition of the aqueous iron (III) chloride solution, stirring was continued at 50 ° C. for 3 hours. At this time, the concentration of the essential raw material with respect to 100% by mass of the solution containing all the precursor raw materials was 50.4% by mass.
The liquid after completion of the stirring was centrifuged to remove the supernatant, and water was added to the resulting precipitate (paste) for redispersion, followed by washing again by centrifugation. The precipitate obtained after the washing operation is dried under reduced pressure at 50 ° C. for 15 hours, whereby an electrode material precursor (average particle size is 100 nm or less and FePO ₄ (core) is coated with polyaniline (shell) ( 7) was obtained.

(Preparation Example 8)
A 500 ml separable flask was charged with 60 ml of water and heated to 50 ° C. with stirring. Next, in a state where stirring was maintained while maintaining the temperature at 50 ° C., 147.87 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 80 ml of the above separable flask. At the same time as the addition of the aqueous solution dissolved in water was started, 36 ml of diammonium hydrogen phosphate (manufactured by Kanto Chemical Co., Ltd.) and 55.56 g of triammonium phosphate trihydrate (manufactured by Kishida Chemical Co., Ltd.) were added to 120 ml of water. And the addition of 30.78 g of aniline (manufactured by Kishida Chemical Co., Ltd., purity 99.5% or more) was started. The time from the start to the end of the addition of the iron (III) chloride aqueous solution, the phosphate aqueous solution and the aniline was 60 minutes. After completion of the addition of the aqueous iron (III) chloride solution, stirring was continued at 50 ° C. for 2 hours. At this time, the concentration of the essential raw material with respect to 100% by mass of the solution containing all the precursor raw materials was 50.9% by mass.
The liquid after completion of the stirring was centrifuged to remove the supernatant, and water was added to the resulting precipitate (paste) for redispersion, followed by washing again by centrifugation. The precipitate obtained after the washing operation is dried under reduced pressure at 50 ° C. for 15 hours, whereby an electrode material precursor (average particle size is 100 nm or less and FePO ₄ (core) is coated with polyaniline (shell) ( 8) was obtained.

(Examples 9 to 11)
The electrode material precursors (6) to (8) obtained in Preparation Examples 6 to 8 are put in mortars, respectively, FePO ₄ and equimolar CH ₃ COOLi contained in each electrode material precursor, and 100 parts by mass of FePO. sucrose and a suitable amount of water 36 parts by weight was added and mixed for _four and homogenized. Next, the mixture was dried at 50 ° C. under reduced pressure, and then placed in a firing furnace. The temperature was raised from room temperature to 400 ° C. over 40 minutes while flowing nitrogen through the firing furnace. After the temperature reached 400 ° C., it was maintained for 3 hours to remove water and volatile organic substances. Subsequently, the temperature was raised from 400 ° C. to 700 ° C. in 30 minutes. Furthermore, after the temperature reaches 700 ° C., it is held for 5 hours, and then cooled to room temperature to obtain electrode materials (9) to (11) having a structure in which LiFePO _{4 as} an active material core is covered with carbon. It was. The nitrogen atom content of the electrode material (9) is 0.58% by mass, the nitrogen atom content of the electrode material (10) is 0.78% by mass, and the nitrogen atom content of the electrode material (11) is 0. It was .75% by mass. Further, the crystallite diameter of the core (LiFePO ₄₎ of electrode material was measured by X-ray diffraction (9) is 58 nm, the crystallite size of the core (LiFePO ₄₎ of the electrode material (10) is 67 nm, the electrode material The crystallite diameter of the core (LiFePO ₄ ) of (11) was 63 nm.

(Preparation Example 9)
In a 500 ml separable flask, 48.16 g of diammonium hydrogen phosphate (manufactured by Kanto Chemical Co., Inc.), 16.41 g of aniline (manufactured by Kishida Chemical Co., Ltd., purity 99.5% or more), N, N-dimethylformamide (Kanto Chemical Co., Ltd.) (Made by Co., Ltd., purity: 99.5% or more) 40 ml and 160 ml of water were charged and stirred and mixed at 40 ° C. Next, 98.58 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 80 ml of water in the above separable flask while maintaining the temperature at 40 ° C. while maintaining stirring. The aqueous solution dissolved in was added over 60 minutes, and the stirring was further continued at 40 ° C. for 5 hours. At this time, the concentration of the essential raw material with respect to 100% by mass of the solution containing all the precursor raw materials was 36.8% by mass.
The liquid after completion of the stirring was centrifuged to remove the supernatant, and water was added to the resulting precipitate (paste) for redispersion, followed by washing again by centrifugation. The precipitate obtained after the washing operation was dried under reduced pressure at 50 ° C. for 15 hours, whereby an electrode material precursor (9) having an average particle diameter of 100 nm or less and FePO 4 (core) coated with polyaniline (shell). )

(Preparation Example 10)
In a 500 ml separable flask, 36.12 g of diammonium hydrogen phosphate (manufactured by Kanto Chemical Co., Ltd.), 55.56 g of triammonium phosphate trihydrate (manufactured by Kishida Chemical Co., Ltd.), aniline (manufactured by Kishida Chemical Co., Ltd., purity) (99.5% or more) 24.62 g and 180 ml of water were charged and stirred and mixed at 40 ° C. Next, with the temperature maintained at 40 ° C., with stirring maintained, 147.87 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 80 ml of water in the separable flask. The aqueous solution dissolved in was added over 60 minutes, and stirring was further continued at 50 ° C. for 3 hours. At this time, the concentration of the essential raw material with respect to 100% by mass of the solution containing all the precursor raw materials was 50.4% by mass.
The liquid after completion of the stirring was centrifuged to remove the supernatant, and water was added to the resulting precipitate (paste) for redispersion, followed by washing again by centrifugation. The precipitate obtained after the washing operation is dried under reduced pressure at 50 ° C. for 15 hours, whereby an electrode material precursor (average particle size is 100 nm or less and FePO ₄ (core) is coated with polyaniline (shell) ( 10) was obtained.

(Examples 12 to 13)
The electrode material precursors (9) to (10) obtained in Preparation Examples 9 to 10 are put in mortars, respectively, FePO ₄ and equimolar CH ₃ COOLi contained in each electrode material precursor, and 100 parts by mass of FePO. sucrose and a suitable amount of water 36 parts by weight was added and mixed for _four and homogenized. Next, the mixture was dried at 50 ° C. under reduced pressure, and then placed in a firing furnace. The temperature was raised from room temperature to 400 ° C. over 40 minutes while flowing nitrogen through the firing furnace. After the temperature reached 400 ° C., it was maintained for 3 hours to remove water and volatile organic substances. Subsequently, the temperature was raised from 400 ° C. to 700 ° C. in 30 minutes. Furthermore, after the temperature reaches 700 ° C., it is held for 5 hours, and then cooled to room temperature to obtain electrode materials (12) to (13) having a structure in which LiFePO _{4 as} the active material core is covered with carbon. It was. The nitrogen atom content of the electrode material (12) was 0.57% by mass, and the nitrogen atom content of the electrode material (13) was 0.74% by mass. Further, the crystallite diameter of the core (LiFePO ₄₎ of electrode material was measured by X-ray diffraction (12) is 55 nm, the crystallite size of the core (LiFePO ₄₎ of the electrode material (13) was 63 nm.

(Comparative Preparation Example 1)
In a 500 ml separable flask, 147.87 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and 140 ml of water were charged and mixed with stirring at 50 ° C. Next, 36.12 g of diammonium hydrogen phosphate (manufactured by Kanto Chemical Co., Inc.) and triammonium phosphate trihydrate were put into the separable flask while maintaining the temperature at 50 ° C. while stirring was maintained. At the same time as addition of an aqueous solution obtained by dissolving 55.56 g (manufactured by Kishida Chemical Co., Ltd.) in 120 ml of water, addition of 30.78 g of aniline (manufactured by Kishida Chemical Co., Ltd., purity 99.5% or more) was started. After the addition of the phosphate aqueous solution and aniline was started, the solution in the flask gradually thickened, and when the addition was completed, the solution was completely gelled, making it difficult to continue stirring. It was. The time from the start to the end of the addition of the aqueous phosphate solution and aniline was 60 minutes.

(Creation of positive electrode film)
A positive electrode composition (9) was obtained by mixing PVdF as a binder, N-methyl-2-pyrrolidinone as a solvent, and the electrode material (9) obtained above. The obtained positive electrode composition (9) was applied on an aluminum foil to prepare a positive electrode film (9).
Also, positive electrode compositions (10) to (13) were prepared in the same manner as described above except that the electrode materials (10) to (13) were used instead of the electrode material (9), respectively. ) To (13) were produced.

(Charge / discharge test)
The produced positive electrode films (9) to (13) were subjected to a battery evaluation by performing a test similar to the charge / discharge test performed for the positive electrode film (5) described above. The results are shown in Table 3.

From the above results, when the active material raw material and the oxidative polymerizable monomer are supplied from the initial stage of the reaction in the coexistence of the oxidant in the reaction solution instead of supplying the oxidant into the reaction solution, the reaction is caused by gelation. Could not continue. From the results shown in Table 3, the positive electrode films prepared using the electrode materials (9) to (13) obtained by synthesizing the precursor while supplying the oxidant into the reaction solution all showed better performance as the positive electrode of the battery. As a result, it was confirmed that the precursor obtained by the method for producing an electrode material precursor of the present invention can be more suitably used as an electrode material exhibiting excellent performance.

(Preparation Example 11)
A 3 l separable flask was charged with 18.34 g of ammonium dihydrogen phosphate (Kanto Chemical Co., Ltd.), 7.14 g of aniline (Kishida Chemical Co., Ltd., purity 99.5% or more) and 1400 ml of water at 40 ° C. Stir and mix. Next, in a state where stirring was maintained while maintaining the temperature at 40 ° C., 43.10 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 700 ml of the separable flask. An aqueous solution dissolved in water was added over 30 minutes, and stirring was further continued at 40 ° C. for 5 hours. At this time, the concentration of the essential raw material with respect to 100% by mass of the solution containing all the precursor raw materials was 3.2% by mass.
The liquid after completion of the stirring was centrifuged to remove the supernatant, and water was added to the resulting precipitate (paste) for redispersion, followed by washing again by centrifugation. The precipitate obtained after the washing operation is dried under reduced pressure at 50 ° C. for 15 hours, whereby an electrode material precursor having an average primary particle size of 100 nm or less and FePO ₄ (core) coated with polyaniline (shell) (11) was obtained.

(Example 14)
The electrode material precursor (11) obtained in Preparation Example 11 was put in a mortar, and 36 parts per mole of FePO ₄ and equimolar CH ₃ COOLi contained in the electrode material precursor (11), 100 parts by mass of FePO ₄ . A part by weight of sucrose and an appropriate amount of water were added, mixed and homogenized to obtain a paste-like mixture. The amount of water contained in this paste-like mixture was 27.5% by mass of the total of the precursor (11) and CH ₃ COOLi.
Subsequently, the mixture was dried at 50 ° C. under reduced pressure, and then placed in a firing furnace. The temperature was raised from room temperature to 400 ° C. over 40 minutes while flowing nitrogen through the firing furnace. After the temperature reached 400 ° C., it was maintained for 3 hours to remove water and volatile organic substances. Subsequently, the temperature was raised from 400 ° C. to 700 ° C. in 30 minutes. Furthermore, after the temperature reached 700 ° C., it was held for 5 hours, and then cooled to room temperature to obtain an electrode material (14) having a core / shell structure in which the active material core was LiFePO ₄ and was coated with carbon. . The nitrogen atom content of the electrode material (14) was 0.34% by mass. The crystallite diameter of the core (LiFePO ₄ ) of the electrode material (14) measured by X-ray diffraction was 47 nm.

(Example 15)
The electrode material precursor (11) obtained in Preparation Example 11 was put in a mortar, and 36 parts per mole of FePO ₄ and equimolar CH ₃ COOLi contained in the electrode material precursor (11), 100 parts by mass of FePO ₄ . Part by mass of sucrose was added, mixed and homogenized to obtain a powdery mixture.
Subsequently, the mixture was dried at 50 ° C. under reduced pressure, and then placed in a firing furnace. The temperature was raised from room temperature to 400 ° C. over 40 minutes while flowing nitrogen through the firing furnace. After the temperature reached 400 ° C., it was maintained for 3 hours to remove water and volatile organic substances. Subsequently, the temperature was raised from 400 ° C. to 700 ° C. in 30 minutes. Furthermore, after the temperature reached 700 ° C., it was held for 5 hours, and then cooled to room temperature to obtain an electrode material (15) having a core / shell structure in which the active material core was LiFePO ₄ and was coated with carbon. . The nitrogen atom content of the electrode material (15) was 0.33% by mass. The crystallite diameter of the core (LiFePO ₄ ) of the electrode material (15) measured by X-ray diffraction was 133 nm.

(Preparation Example 12)
In a 500 ml separable flask, 30.10 g of diammonium hydrogen phosphate (manufactured by Kanto Chemical Co., Ltd.), 10.20 g of aniline (manufactured by Kishida Chemical Co., Ltd., purity 99.5% or more), N, N-dimethylformamide (Kanto Chemical Co., Ltd.) (Made by Co., Ltd., purity 99.5% or more) 21 ml and water 200 ml were charged and stirred and mixed at 60 ° C. Next, in a state where stirring was maintained while maintaining the temperature at 60 ° C., 61.61 g of iron (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 100 ml of the separable flask. An aqueous solution dissolved in water was added over 30 minutes, and stirring was further continued at 60 ° C. for 5 hours. At this time, the concentration of the essential raw material with respect to 100% by mass of the solution containing all the precursor raw materials was 24.1% by mass.
The liquid after completion of the stirring was centrifuged to remove the supernatant, and water was added to the resulting precipitate (paste) for redispersion, followed by washing again by centrifugation. The precipitate obtained after the washing operation is dried under reduced pressure at 50 ° C. for 15 hours, whereby an electrode material precursor having an average primary particle size of 100 nm or less and FePO ₄ (core) coated with polyaniline (shell) (12) was obtained.

(Example 16)
The electrode material precursor (12) obtained in Preparation Example 12 was put in a mortar, and FePO ₄ and equimolar CH ₃ COOLi (melting point: 286 ° C.) contained in the electrode material precursor (12), 100 parts by mass. 36 parts by mass of sucrose and an appropriate amount of water were added to FePO ₄ and mixed to make uniform.
Next, the mixture was dried at 50 ° C. under reduced pressure, and then placed in a firing furnace. The temperature was raised from room temperature to 400 ° C. over 40 minutes while flowing nitrogen through the firing furnace. After the temperature reached 400 ° C., it was maintained for 3 hours to remove water and volatile organic substances. Subsequently, the temperature was raised from 400 ° C. to 700 ° C. in 30 minutes. Furthermore, after the temperature reached 700 ° C., it was held for 5 hours, and then cooled to room temperature, to obtain an electrode material (16) having a core-shell structure in which the active material core was LiFePO ₄ and was coated with carbon. . The nitrogen atom content of the electrode material (16) was 0.54% by mass. Further, the crystallite diameter of the core (LiFePO ₄ ) of the electrode material (16) measured by X-ray diffraction was 61 nm.

(Example 17)
The electrode material precursor (12) obtained in Preparation Example 12 is put in a mortar, and ½ mol amount of FePO ₄ and equimolar CH ₃ COOH, FePO ₄ contained in the electrode material precursor (12) Li ₂ CO ₃ and 100 parts by mass of FePO ₄ were mixed with 36 parts by mass of sucrose and an appropriate amount of water, and homogenized.
Next, the mixture was dried at 50 ° C. under reduced pressure, and then placed in a firing furnace. The temperature was raised from room temperature to 400 ° C. over 40 minutes while flowing nitrogen through the firing furnace. After the temperature reached 400 ° C., it was maintained for 3 hours to remove water and volatile organic substances. Subsequently, the temperature was raised from 400 ° C. to 700 ° C. in 30 minutes. Furthermore, after the temperature reached 700 ° C., it was held for 5 hours, and then cooled to room temperature to obtain an electrode material (17) having a core-shell structure in which the active material core was LiFePO ₄ and was coated with carbon. . The nitrogen atom content of the electrode material (17) was 0.53 mass%. The crystallite diameter of the core (LiFePO ₄ ) of the electrode material (17) measured by X-ray diffraction was 70 nm.

(Example 18)
Instead of FePO ₄ and equimolar CH ₃ COOLi contained in the electrode material precursor (12) in Example 16, 1/2 mole amount of Li _{2 with} respect to FePO ₄ contained in the electrode material precursor (12). An electrode material (18) having a core / shell structure in which the active material core was LiFePO ₄ and was coated with carbon was obtained in the same manner as in Example 16 except that CO ₃ (melting point: 723 ° C.) was used. The nitrogen atom content of the electrode material (18) was 0.53 mass%. The crystallite diameter of the core (LiFePO ₄ ) of the electrode material (18) measured by X-ray diffraction was 96 nm.

(Preparation of positive electrode film)
After adding 0.6 g of PVdF (Kynar HSV-900, manufactured by Arkema) to 40 g of N-methyl-2-pyrrolidinone, a uniform solution was obtained, and 1.0 g of Ketjen Black EC-300J (Lion) was used as above. The obtained electrode material (14) was added and dispersed in the order of 18.0 g to obtain a positive electrode composition (14). The obtained positive electrode composition was coated on an aluminum foil using an applicator. The film was dried at 100 ° C. for 10 minutes, then at 200 ° C. for 60 minutes, and further subjected to hot pressing at 200 ° C. for 30 minutes to produce a positive electrode film (14) of about 40 μm.
Also, positive electrode compositions (15) to (18) were prepared in the same manner as described above except that the electrode materials (15) to (18) were used instead of the electrode materials (14), respectively. 15) to (18) were produced.

(Charge / discharge test)
The produced positive electrode films (14) to (18) were subjected to battery evaluation of a coin cell (CR2032) using a charge / discharge measuring apparatus ACD-001 (manufactured by Asuka Electronics Co., Ltd.). The results are shown in Table 4.
Positive electrode: prepared positive electrode film Negative electrode: Li foil electrolyte: 1 mol% / L LiPF6 EC / EMC = 1/1 (manufactured by Kishida Chemical Co., Ltd.)
Separator: Porous polypropylene membrane Celgard 2500 (manufactured by Celgard)
Charging / discharging conditions: 0.2C
Cut-off voltage: 2.5-4.0V
Evaluation temperature: 30 ° C

The results of Examples 14 to 18 revealed the following.
It was confirmed that the positive electrode film produced using the electrode material (14) exhibited better performance as the positive electrode of the battery than the positive electrode film produced using the electrode material (15). From this, when preparing a mixture by mixing the electrode material precursor and other raw materials containing lithium salt, by mixing in a paste in the presence of a solvent rather than simply dry-mixing the powders It has been demonstrated that the obtained lithium-containing electrode material can exhibit higher performance.
In addition, both positive electrode films produced using the electrode materials (16) and (17) exhibit better performance as the positive electrode of the battery than the positive electrode film produced using the electrode material (18). It was confirmed. From this, when the precursor core is a trivalent iron compound such as iron (III) phosphate, a lithium-containing electrode material obtained by using a lithium salt having a melting point of 400 ° C. or lower as the lithium salt is obtained. It has been demonstrated that higher performance can be demonstrated.
From these results, it was confirmed that the lithium-containing electrode material obtained by the method for producing a lithium-containing electrode material of the present invention can be more suitably used as an electrode material exhibiting excellent performance.

Claims (10)

An electrode material containing an active material,
The electrode material, wherein the active material has a structure coated with a conductive carbon material, and a nitrogen atom content with respect to 100% by mass of the total amount of the active material is 0.3% by mass or more. The active material is
LiMPO ₄
2. The electrode material according to claim 1, comprising a compound represented by (M represents one or more metals selected from Fe, Co, Mn, and Ni). The electrode material according to claim 1, wherein the structure covered with the conductive carbon material is formed by firing a conductive carbon material precursor in a nitrogen atmosphere. 4. The electrode material according to claim 1, wherein the conductive carbon material precursor has a nitrogen atom in its structure. An electrode comprising the electrode material according to any one of claims 1 to 4. A battery comprising the electrode according to claim 5. A method for producing the electrode material according to any one of claims 1 to 4,
The production method includes the steps of producing precursor fine particles in a solution containing an active material raw material and producing an electrode material precursor by forming a coating structure with a polymer produced by polymerization of monomers on the fine particles,
The manufacturing process includes a process of using an oxidative polymerizable monomer and an oxidizing agent as essential raw materials together with an active material raw material, and a pH of the solution of 0.3 or more and 3.0 or less. . A method for producing the electrode material according to any one of claims 1 to 4,
The production method includes the steps of producing precursor fine particles in a solution containing an active material raw material and producing an electrode material precursor by forming a coating structure with a polymer produced by polymerization of monomers on the fine particles,
The manufacturing process includes a process of synthesizing a precursor while supplying an oxidant into a reaction solution using an oxidative polymerizable monomer and an oxidant as essential raw materials together with an active material. . A method for producing the electrode material according to any one of claims 1 to 4,
The production method is a method of producing a lithium-containing electrode material in which active material fine particles have a coating structure of a carbon component,
In the production method, an electrode material precursor in which precursor fine particles have a polymer-coated structure and a lithium salt are essential components, and a mixture containing the essential components is prepared in the presence of a solvent, and then the mixture is heat-treated. The manufacturing method of the electrode material characterized by including a process. A method for producing the electrode material according to any one of claims 1 to 4,
The production method is a method of producing a lithium-containing electrode material in which active material fine particles have a coating structure of a carbon component,
In the production method, an active material raw material and an oxidation polymerizable monomer and an oxidizing agent are used as essential raw materials, and the concentration of the essential raw materials is 3 to 60% by mass with respect to 100% by mass of the solution containing all precursor raw materials. Forming a precursor fine particle and forming a coating structure with a polymer formed by polymerization of an oxidative polymerizable monomer on the fine particle to produce an electrode material precursor; and the melting point of the electrode material precursor is 400 ° C. A method for producing an electrode material, comprising: preparing a mixture containing the following lithium salt as an essential component and then heat-treating the mixture.

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