TWI682037B - Regeneration method of lithium composite oxide, lithium composite oxide, electrochemical device and lithium ion secondary battery - Google Patents

Abstract

The present invention provides a method for regenerating a lithium composite oxide, which can regenerate a lithium composite oxide with excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device at a low cost.

A method for regenerating a lithium composite oxide is characterized by including a step of preparing a lithium composite precursor for electrochemically or chemically extracting lithium locally, and a step of reacting a lithium compound with the lithium composite precursor for extracting lithium locally.

Description

Regeneration method of lithium composite oxide, lithium composite oxide, electrochemical device and lithium ion secondary battery

The invention relates to a lithium composite oxide regeneration method, a lithium composite oxide, an electrochemical device, and a lithium ion secondary battery.

In recent years, small electronic devices representing mobile terminals and the like have been widely spread, and they are strongly required to be more compact, lighter, and longer-lived. For such market requirements, the development of secondary batteries that are particularly small and lightweight, and that can achieve high energy density is underway. This secondary battery is not limited to small electronic devices, and is also being studied for application to large-scale electronic devices represented by automobiles and power storage systems represented by homes, etc.

Among them, the lithium-ion secondary battery system is small and easy to increase in capacity, and has great expectations. Because it can get higher energy density than lead batteries and nickel-cadmium batteries.

The lithium ion secondary battery system includes a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode and the negative electrode system contain a positive electrode active material and a negative electrode active material for charge and discharge reactions.

Previously, it was proposed that there will be six parties belonging to the space group R-3m A non-aqueous electrolyte secondary battery using a layered rock salt structure of the crystal system and a lithium composite oxide containing a positive electrode material of a rare metal transition metal such as cobalt and nickel as a positive electrode active material.

However, since the lithium composite oxide used for the positive electrode contains many transition metals such as cobalt, which is a rare metal, it becomes one of the main reasons for increasing the material cost of lithium ion secondary batteries. Moreover, if it is considered that about 20% of the cobalt resources are currently used in the battery industry, it can be considered that if the lithium composite oxide containing many transition metals such as cobalt, which is a rare metal, is consumed according to the current situation, it is difficult to respond to the next two The need to expand the secondary battery.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 3425206

[Patent Document 2] Japanese Patent Laid-Open No. 10-330855

[Patent Document 3] Japanese Patent Laid-Open No. 11-054159

[Patent Document 4] Japanese Patent Application Publication No. 2012-072488

[Patent Document 5] Japanese Patent Application Publication No. 2007-122885

[Patent Document 6] Japanese Patent Laid-Open No. 10-287864

[Patent Document 7] Japanese Patent Laid-Open No. 2004-214025

As mentioned above, because of the positive electrode activity containing transition metals The material system is restricted by resources such as cobalt, which is a rare metal, so there is a problem that the price of a lithium ion secondary battery including such a positive electrode active material becomes high. In order to make lithium ion secondary batteries cheap, regeneration of lithium composite oxides is necessary and indispensable. However, the lithium composite oxide used after one charge and discharge is generally re-dissolved to obtain a hydroxide, and then mixed with a lithium compound for synthesis. However, in this method, it is necessary to separately recover and regenerate lithium and transition metals, and there is a problem that the manufacturing cost increases. In addition, even if the regeneration is performed in this way, impurities such as sodium are more likely to enter during the synthesis of the precipitate. Therefore, the surface impedance of the positive electrode active material increases, and it is difficult to obtain a sufficient charge and discharge capacity.

For cathode materials other than those containing cobalt, it is also important to obtain cost competitiveness, and it is becoming more and more important to regenerate systems more cheaply.

In addition, in recent years, various studies have been made on the electrode configuration of a lithium ion secondary battery using a high capacity negative electrode containing a negative electrode active material such as silicon oxide. High-capacity negative electrodes containing negative-electrode active materials such as silicon oxide are required because of the large number of positive-electrode materials, so the need for regeneration of the positive electrode is even higher. In addition, various studies have been made on the positive electrode materials of lithium ion secondary batteries or electrolytic cells combined with high capacity negative electrodes. In order to improve the characteristics of the entire battery, it is very important to develop a positive electrode material that is compatible with a high-capacity negative electrode containing a negative electrode active material such as silicon oxide. At this point, the inventors have discovered that the regenerated cathode material, which contains a number of resistance The high-capacity negative electrode active material represented by silicon oxide, which has improved resistance and low charge-discharge efficiency, has good suitability for negative electrodes.

The lithium-cobalt composite oxide manufactured by the previous method is a precursor of cobalt oxide, cobalt hydroxide, or a co-precipitate of nickel-cobalt-manganese hydroxide, mixed with a lithium compound, and sintered to obtain a composite. However, there are also many constraints on cobalt resources. Because they are rare metals, the price changes at the time of purchase are also large. For the expanding needs of lithium-ion batteries, it is strongly expected to establish countermeasures for environmental pollution caused by the used lithium-ion batteries, and to study the recovery and valuable use of valuable metals. As a method for recovering a valuable metal such as cobalt from a lithium ion battery having the above-described structure, it is often the case that dry processing or incineration processing described in Patent Literature 1 and Patent Literature 2, for example, is performed.

As a method for regenerating a lithium-cobalt composite oxide proposed in Patent Document 3, cobalt is extracted with an acid at a time, and the raw material of the oxide is used for synthesis. However, since cobalt is extracted in a liquid phase, the procedures are complicated and there are many impurities. The legal system cannot say that it is appropriate. When leaching with a high concentration of acid is used, it has a problem of cost due to long-term heat treatment, use of acid, and use of a large amount of neutralizer.

In addition, a method for leaching valuable metals in a positive electrode active material of a lithium ion battery formed of a composite oxide composed of a transition metal containing manganese, which is proposed in Patent Document 4, is contained in an aqueous solution to which sulfuric acid is added. Among the foregoing positive electrode active materials, the first step of dissolving the sulfuric acid solution-soluble component is separated from the first step without solid-liquid separation. Hydrogen peroxide is added to the sulfuric acid leaching slurry solution, and it is more leached in The leaching method of the positive electrode active material in the second step of the unleached components remaining in the sulfuric acid leaching slurry. However, this method also uses acid to dissolve and regenerate rare metals. There are many impurities and the manufacturing cost becomes large.

Moreover, in Patent Document 5, it advocates the efficient separation and recovery of valuable metals such as Li, Ni, Co, etc. in order to use dry-processes such as heating and incineration from used lithium ion batteries. A method of immersing and stirring in a sulfuric acid aqueous solution having a pH of 0 to 3.0, peeling off the positive electrode active material from the positive electrode substrate, and separating and recovering the solid as it is. However, the so-called extraction from the battery with acid is concerned with the dissolution of metal components from the collector , Impure substances increase, and the characteristics are not ideal.

In addition, Patent Document 6 advocates the first step of separating the eluent after adding mineral acid or a mixed solution of mineral acid and hydrogen peroxide to the positive electrode active material for lithium ion secondary batteries. The second step of contacting the separated eluent with an organic solvent containing a metal extractant for extraction separation, followed by the third step of reverse extraction with contact of the organic solvent phase of the extraction solution with mineral acid, but The productive point of view is regarded as unfavorable.

In addition, Patent Document 7 shows a cobalt recovery method in a lithium ion battery, which includes a first extraction step of extracting and separating cobalt contained in a positive electrode plate constituting a lithium ion battery under a first acidic solvent, In the second extraction step, the cobalt contained in the magnetic deposit selected by the magnetic separation step and the cobalt contained in the extraction residue floating or precipitated in the first acidic solvent are extracted and separated under the second acidic solvent. However, this method is due to the use of acid, impurities are easy to enter, there are still production steps It is complicated, costs production costs, and in the case of regeneration by the above-mentioned method, it becomes a problem that the charge-discharge capacity is inferior to the original compound.

The present invention has been made in view of the above problems, and its object is to provide a method for regenerating a lithium composite oxide, which can regenerate a lithium composite with excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device at low cost Oxide.

In order to achieve the above object, the present invention provides a method for regenerating a lithium composite oxide, which is characterized by including a step of preparing a lithium composite precursor for electrochemically or chemically extracting lithium locally and a lithium composite precursor for extracting lithium locally The step of reacting the lithium compound.

In this way, by using a lithium composite precursor that locally extracts lithium electrochemically or chemically to react a lithium compound, a lithium composite oxide having excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device can be used Low cost regeneration.

In this case, the step of reacting includes mixing the lithium composite precursor for extracting lithium locally with the lithium compound and sintering, and the reaction is preferably performed.

As a method of reacting a lithium compound with a lithium composite precursor that locally extracts lithium, a method of mixing and sintering the lithium composite precursor that locally extracts lithium with the foregoing lithium compound can be suitably used.

At this time, the aforementioned step of reacting includes mixing the lithium composite precursor of the local lithium extraction with the lithium compound to make The stage of hydrothermal reaction is also ideal.

As a method of reacting a lithium compound with a lithium composite precursor that extracts lithium locally, a method of mixing a lithium compound precursor that extracts lithium locally with the foregoing lithium compound to perform a hydrothermal reaction may also be suitably used.

At this time, the aforementioned lithium composite precursor that locally extracts lithium can be set as the following general formula (1): Li _1-x Co _1-z M _z O ₂ (0<x<1, 0≦z<1) . . . (1) (In the formula, M series represents one or more metal elements selected from the group of Mn, Ni, Fe, V, Cr, Al, Nb, Ti, Cu, Zn.) The lithium composite oxide obtained in the above-mentioned reaction step is represented by the following general formula (2): Li _1-y Co _1-z M _z O ₂ (0≦y<x, 0≦z<1 ). . . (2) (M-type in the formula represents a lithium-cobalt-based composite oxide represented by one or more metal elements selected from the group consisting of Mn, Ni, Fe, V, Cr, Al, Nb, Ti, Cu, and Zn).

Assuming that the lithium composite precursor that partially extracts lithium and the lithium composite oxide obtained by the reaction are as described above, it can be used as a cathode active material of an electrochemical device with a more excellent charge and discharge capacity. The lithium composite oxide is regenerated.

At this time, the aforementioned lithium composite precursor for partial extraction of lithium can be set as the following general formula (3): Li _1-x Fe _1-z M _z PO ₄ (0<x<1, 0≦z<1) . . . (3) (In the formula, M series represents one or more metal elements selected from the group of Co, Mn, Ni, V, Cr, Al, Nb, Ti, Cu, Zn.) Oxide, the lithium composite oxide obtained by the above-mentioned reaction step can be represented by the following general formula (4): Li _1-y Fe _1-z M _z PO ₄ (0≦y<x, 0 ≦z<1). . . (4) (M-type in the formula represents a lithium iron phosphorus-based composite oxide represented by one or more metal elements selected from the group of Co, Mn, Ni, V, Cr, Al, Nb, Ti, Cu, and Zn) .

Assuming that the lithium composite precursor that partially extracts lithium and the lithium composite oxide obtained by the reaction are as described above, it can be used as a cathode active material of an electrochemical device with a more excellent charge and discharge capacity. The lithium composite oxide is regenerated.

At this time, the aforementioned lithium composite precursor for partial extraction of lithium can be set as the following general formula (5): Li _3-x V _2-z M _z (PO ₄ ) ₃ (0<x<3, 0≦z <2). . . (5) (In the formula, M series represents one or more metal elements selected from the group of Co, Mn, Ni, Fe, Cr, Al, Nb, Ti, Cu, Zn.) Oxide, the lithium composite oxide obtained by the above-mentioned reaction step can be set as the following general formula (6): Li _3-y V _2-z M _z (PO ₄ ) ₃ (0≦y< x, 0≦z<2). . . (6) (M-type in the formula represents a lithium vanadium-phosphorus composite oxide represented by Co, Mn, Ni, Fe, Cr, Al, Nb, Ti, Cu, and Zn) .

Assuming that the lithium composite precursor that partially extracts lithium and the lithium composite oxide obtained by the reaction are as described above, it can be used as a cathode active material of an electrochemical device with a more excellent charge and discharge capacity. The lithium composite oxide is regenerated.

At this time, as the aforementioned lithium composite precursor, two types can be used The above lithium composite precursor.

The present invention is used as a lithium composite precursor and can also be applied to the case where two or more lithium composite precursors are used. In this case, the composition of the regenerated lithium composite oxide can also be adjusted.

In this case, if the lithium composite precursor is prepared to contain carbon, it is desirable that the lithium composite oxide obtained in the step of reacting it contains carbon contained in the lithium composite precursor.

In this case, the step of reacting includes the step of reacting the lithium composite precursor with a carbon compound, and it is also desirable that the lithium composite oxide obtained by the step of reacting contains carbon.

In this way, the lithium composite oxide after the reaction is made to contain carbon, and the lithium composite oxide having more excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device can be regenerated.

In addition, the present invention provides a lithium composite oxide regenerated by the above method.

Such a lithium composite oxide has excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device, and can be manufactured at a low cost.

In addition, the present invention provides an electrochemical device characterized by having a negative electrode and a positive electrode, wherein the negative electrode is composed of negative electrode active material particles having a charge-discharge efficiency of 80% or less when used as a negative electrode active material of the electrochemical device Of the negative electrode active material layer and the negative electrode current collector, the positive electrode is composed of the positive electrode active material containing the lithium composite oxide The mass layer is composed of the positive electrode current collector.

If it is such an electrochemical device, it can be manufactured with low cost while having excellent charge and discharge capacity.

In addition, the present invention provides an electrochemical device characterized by having a negative electrode and a positive electrode, wherein the negative electrode is composed of negative electrode active material particles containing silicon oxide represented by a composition formula of SiO _x (0.5≦x<1.6) The negative electrode active material layer is composed of a negative electrode current collector, and the positive electrode is composed of a positive electrode active material layer containing the above lithium composite oxide and a positive electrode current collector.

If it is such an electrochemical device, it can be manufactured with low cost while having excellent charge and discharge capacity.

In addition, the present invention provides a lithium ion secondary battery, which is characterized by having a negative electrode and a positive electrode, wherein the negative electrode is composed of a lithium ion secondary battery containing a negative electrode active material when the charge and discharge efficiency is 80% or less The negative electrode active material layer of the negative electrode active material particles and the negative electrode current collector are composed of the positive electrode active material layer containing the above-mentioned lithium composite oxide and the positive electrode current collector.

If it is such a lithium ion secondary battery, it is an excellent charge-discharge capacity, and it can be manufactured at a low cost.

In addition, the present invention provides a lithium ion secondary battery, which is characterized by having a negative electrode and a positive electrode, wherein the negative electrode is composed of a negative electrode activity containing silicon oxide represented by a composition formula of SiO _x (0.5≦x<1.6) The negative electrode active material layer of the material particles and the negative electrode current collector are composed of the positive electrode active material layer containing the above-mentioned lithium composite oxide and the positive electrode current collector.

If it is such a lithium ion secondary battery, it is an excellent charge-discharge capacity, and it can be manufactured at a low cost.

As described above, according to the regeneration method of the lithium composite oxide of the present invention, the lithium composite oxide having excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device can be regenerated at a low cost. In addition, the lithium composite oxide of the present invention has excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device, and can be manufactured at a low cost. Furthermore, if it is the electrochemical device of the present invention, it has excellent charge and discharge capacity and can be manufactured at low cost. In addition, the lithium ion secondary battery of the present invention has excellent charge and discharge capacity and can be manufactured at low cost.

[Figure 1] is a flow chart of the lithium composite oxide regeneration method of the present invention.

Hereinafter, the present invention will be described in detail while referring to the drawings as an example of an embodiment, but the present invention is not limited to this.

As mentioned earlier, in the previous regeneration of lithium composite oxides In the method, there is room for improvement in the charge and discharge capacity when the regenerated lithium composite oxide is used as the positive electrode active material of an electrochemical device, and the regeneration cost. Therefore, the inventors have repeatedly focused on the regeneration method of the lithium composite oxide, which can be used as a lithium composite oxide with excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device. Low cost regeneration. As a result, it was found that a lithium composite oxide that locally extracts lithium electrochemically or chemically can react with a lithium compound, and can be used as a lithium composite oxide having excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device The invention can be completed by regeneration at low cost.

First, referring to FIG. 1, a method of regenerating the lithium composite oxide of the present invention will be described.

First, a lithium composite precursor that locally extracts lithium electrochemically or chemically is prepared (see step S11 in FIG. 1). The so-called lithium composite precursor that locally extracts lithium electrochemically, specifically, it is a charge-discharger in the shape of particles without being mounted on the current collector, and a charge-discharger in the form of being mounted on the current collector, such as An organic solvent such as N-methylpyrrolidone is applied as a paint and applied to the current collector after charging and discharging. In addition, the so-called lithium composite precursor that chemically extracts lithium locally is specifically a person who leaches lithium by immersing it in various acidic liquids, a person who sinters at a high temperature, and lithium volatilizes. In addition, the lithium composite precursor that extracts lithium electrochemically or chemically can also be used to dissolve and remove the used electrode after the charge and discharge using an organic solvent, or it can be electrochemically charged and discharged from powder or particles To extract lithium, but by charging and discharging in the state of a coin battery or using an electrolytic cell It is ideal for charging and discharging, the one that has extracted lithium is easy to take out and easy to regenerate. If a lithium composite precursor with partially eliminated lithium is used, the lithium remains partially, so it is easier to generate the lithium composite oxide than when the raw material of the co-precipitated hydroxide is used, and the lithium used The amount of the compound becomes smaller, and the lithium composite oxide can be produced at low cost.

Next, the lithium composite precursor that locally extracts lithium is reacted with the lithium compound (refer to step S12 in FIG. 1). Examples of the lithium compound system include lithium carbonate, lithium hydroxide‧monohydrate, lithium oxide, lithium oxalate, lithium acetate, lithium phosphate, and the like, but lithium hydroxide‧monohydrate is desirable. Lithium hydroxide monohydrate is very reactive and easy to handle.

Here, in step S12 of FIG. 1, it is desirable that a lithium composite precursor that locally extracts lithium is mixed with a lithium compound and sintered to make it react with the lithium compound. In the case of sintering, it is desirable to add a calcination step before the sintering step. The calcination temperature is 100 to 550°C, ideally 100 to 500°C, and the calcination time is 30 minutes to 5 hours, ideally 2 to 5 hours. In the above sintering step, the sintering temperature is 600 to 1100°C, ideally 600 to 1000°C, more preferably 600 to 800°C, and the sintering time is 1 to 50 hours, ideally 2 to 15 hours, more ideally 2 to 8 hour. The above sintering can also be performed in any environment, for example, in the atmosphere, inert environment, oxygen environment, etc., but because the lithium composite precursor system already has oxygen, it is ideal to perform in a nitrogen environment.

In addition, in step S12 of FIG. 1, it is also desirable that a lithium composite precursor that locally extracts lithium is mixed with a lithium compound to perform a hydrothermal reaction, so that it reacts with the lithium compound.

Furthermore, in step S12 of FIG. 1, various methods may be used in combination. For example, two or more methods of performing sintering, applying hydrothermal treatment, increasing the number of sintering, and performing particle molding and sintering may be used in combination.

The lithium composite precursor for partial extraction of lithium can be set as the following general formula (1): Li _1-x Co _1-z M _z O ₂ (0<x<1, 0≦z<1). . . (1) (In the formula, M represents a composite oxide represented by one or more metal elements selected from the group consisting of Mn, Ni, Fe, V, Cr, Al, Nb, Ti, Cu, and Zn.) The lithium composite oxide obtained by reacting with a lithium compound is represented by the following general formula (2): Li _1-y Co _1-z M _z O ₂ (0≦y<x, 0≦z<1) . . . (2) (In the formula, M series represents one or more metal elements selected from the group of Mn, Ni, Fe, V, Cr, Al, Nb, Ti, Cu, Zn.) Thing. Assuming that the lithium composite precursor that partially extracts lithium and the lithium composite oxide obtained by the reaction are as described above, it can be used as a cathode active material of an electrochemical device with a more excellent charge and discharge capacity. The lithium composite oxide is regenerated.

The lithium composite precursor for partial extraction of lithium can be set as the following general formula (3): Li _1-x Fe _1-z M _z PO ₄ (0<x<1, 0≦z<1). . . (3) (In the formula, M series represents one or more metal elements selected from the group of Co, Mn, Ni, V, Cr, Al, Nb, Ti, Cu, Zn.) Oxide, the lithium composite oxide obtained by reacting with a lithium compound can be represented by the following general formula (4): Li _1-y Fe _1-z M _z PO ₄ (0≦y<x, 0≦ z<1). . . (4) (In the formula, M series represents one or more metal elements selected from the group of Co, Mn, Ni, V, Cr, Al, Nb, Ti, Cu, Zn.) Oxide. Assuming that the lithium composite precursor that partially extracts lithium and the lithium composite oxide obtained by the reaction are as described above, it can be used as a cathode active material of an electrochemical device with a more excellent charge and discharge capacity. The lithium composite oxide is regenerated.

The lithium composite precursor for partial extraction of lithium can be set as the following general formula (5): Li _3-x V _2-z M _z (PO ₄ ) ₃ (0<x<3, 0≦z<2). . . (5) (In the formula, M series represents one or more metal elements selected from the group of Co, Mn, Ni, Fe, Cr, Al, Nb, Ti, Cu, Zn.) Oxide, the lithium composite oxide obtained by reacting with a lithium compound can be represented by the following general formula (6): Li _3-y V _2-z M _z (PO ₄ ) ₃ (0≦y<x , 0≦z<2). . . (6) (In the formula, M series represents one or more metal elements selected from the group of Co, Mn, Ni, Fe, Cr, Al, Nb, Ti, Cu, Zn.) Oxide. Assuming that the lithium composite precursor that partially extracts lithium and the lithium composite oxide obtained by the reaction are as described above, it can be used as a cathode active material of an electrochemical device with a more excellent charge and discharge capacity. The lithium composite oxide is regenerated.

As the above lithium composite precursor, two or more kinds of lithium composite precursors can be used. Two or more types of lithium composite precursors other than those exemplified in the general formulas (1), (3), and (5) above, for example, a composite oxide composed of lithium and a transition metal element, or having lithium Choose from phosphate compounds with transition metal elements. Even among these composite oxides, compounds having at least one kind of nickel, iron, manganese, and cobalt are desirable. Examples of the composite oxide having lithium and transition metal elements include lithium cobalt composite oxide Li _a CoO ₂ (0<a<1) and lithium nickel composite oxide Li _a NiO ₂ (0<a<1) , Phosphoric acid compounds with lithium and transition metal elements, for example, lithium iron phosphate compounds (LiFePO ₄ ) or lithium iron manganese phosphate compounds Li _a Fe _1-c Mn _c PO ₄ (0<a<1, 0<c <1), lithium vanadium phosphate compound Li _3-a V ₂ (PO ₄ ) ₃ (0<a<3), etc.

As the above-mentioned lithium composite precursor, a lithium composite oxide obtained by reacting with a lithium compound and containing a lithium composite precursor is prepared. The carbon contained in the substance is ideal. The above-mentioned step of reacting includes the step of reacting the above-mentioned lithium composite precursor with a carbon compound, and the lithium composite oxide obtained by the above-mentioned step of reacting preferably contains carbon. The lithium composite oxide after the reaction is made to contain carbon, and the lithium composite oxide having a more excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device can be regenerated.

According to the regeneration method of the lithium composite oxide of the present invention described above, the lithium composite oxide having excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device can be regenerated at a low cost.

Next, the lithium composite oxide of the present invention will be explained.

The lithium composite oxide of the present invention is a lithium composite oxide regenerated by the above-mentioned method of regenerating the lithium composite oxide of the present invention. Such a lithium composite oxide has excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device, and can be manufactured at a low cost.

The above lithium composite oxide can be used as a positive electrode active material of various electrochemical devices (for example, batteries, sensors, electrolytic cells, etc.). Here, the so-called "electrochemical device" refers to a device that includes a plate material that flows current, that is, a device that can generally draw out electrical energy, and includes the concept of an electrolytic cell, a primary battery, and a secondary battery. In addition, the term "secondary battery" is a concept that includes so-called accumulators such as lithium ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries, and electric storage elements such as electric double-layer capacitors. The above lithium composite oxides are It is not suitable as an electrode material for lithium ion secondary batteries and electrolytic cells. The shape of the electrolytic cell can be any shape, for example, it can contain the electrode plate material flowing through the current. For the shape of the lithium ion secondary battery, any of coin type, button type, sheet type, cylindrical type, and angle type can also be used. Still, the application of the lithium ion secondary battery to which the lithium composite oxide of the present invention is applied is not particularly limited, and examples include notebook computers, laptop computers, pocket word processors, portable telephones, and wireless telephones. , Portable CDs, radios and other electronic equipment, automobiles, electric vehicles, game equipment and other consumer electronic equipment.

Hereinafter, the constituent elements of the electrochemical device and lithium ion secondary battery to which the above-mentioned lithium composite oxide is applied will be described.

〔Positive active material layer〕

The positive electrode active material layer contains 50 to 100% by mass of the lithium composite oxide of the present invention. In addition, it may contain any one or more of the positive electrode active materials capable of absorbing and releasing lithium ions, and may contain other materials such as a binder, a conductive aid, a dispersant, etc. according to the design.

〔positive electrode〕

The positive electrode system has, for example, positive electrode active material layers on both sides or one side of the current collector. The current collecting system is preferably formed of a conductive material such as aluminum.

[Negative electrode active material layer]

The negative electrode active material is any one of silicon oxide represented by the general formula SiO _x (0.5≦x<1.6), or a mixture of 2 or more of these components. The negative electrode active material layer contains the above negative electrode active material, and other materials containing a binder, a conductive auxiliary agent, a dispersant, etc. according to the design are also preferable.

〔negative electrode〕

The negative electrode system has the same configuration as the positive electrode described above, and for example, has a negative electrode active material layer on one side or both sides of the current collector. This negative electrode is ideal for the capacity obtained by the lithium composite oxide active material agent (as the charging capacity of the battery), and the negative electrode charging capacity becomes large. This is to suppress the precipitation of lithium metal on the negative electrode.

〔Adhesive materials〕

As the binder, for example, any one or more types of polymer materials, synthetic rubber, and the like can be used. The polymer material is, for example, polyvinylidene fluoride, polyimide, polyimide, imide, aromatic polyamide, polyacrylic acid, lithium polyacrylate, or carboxymethyl cellulose. Synthetic rubber, for example, styrene-butadiene rubber, fluorine rubber, ethylene propylene diene, and the like.

〔Conducting aids〕

As the lithium composite oxide conductive auxiliary agent and negative electrode conductive auxiliary agent, for example, any one or more types of carbon materials such as carbon black, acetylene black, graphite, Ketjen black, carbon nanotubes, and carbon nanofibers can be used.

〔Electrolyte〕

At least a part of the active material layer or the separator is impregnated with a liquid electrolyte (electrolyte). This electrolyte has electrolyte salts dissolved in a solvent, and other materials containing additives are also preferred. Examples of the solvent system include non-aqueous solvents. Examples of non-aqueous solvents include the following materials. Ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, 1,2-dimethoxyethane or tetrahydrofuran. Among them, at least one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are most preferable. This is because of better characteristics. In addition, in this case, if high-viscosity solvents such as ethylene carbonate and propylene carbonate are combined with low-viscosity solvents such as dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate, more advantageous characteristics can be obtained. This is because the dissociation or ion mobility of the electrolyte salt increases.

In particular, it is preferable to contain at least one of halogenated chain carbonate or halogenated cyclic carbonate as a solvent. This is because a stable coating is formed on the surface of the negative electrode active material during charging and discharging, especially during charging. A halogenated chain carbonate is a chain carbonate having halogen as a constituent element (at least one hydrogen is replaced by halogen). Halogenated cyclic carbonate is a cyclic carbonate having halogen as a constituent element (at least one hydrogen is replaced by halogen).

The type of halogen is not particularly limited, but fluorine is preferred. This is because it forms a high-quality coating compared to other halogens. In addition, the more halogen number system, the more ideal, because the resulting coating is more stable, reducing the decomposition reaction of the electrolyte. Halogenated chain carbonates, examples of which include carbonic acid Fluoromethyl methyl ester, difluoromethyl methyl carbonate, etc. Examples of halogenated cyclic carbonates include 4-fluoro-1,3-dioxolane-2-one or 4,5-difluoro-1,3-dioxolane- 2-one, etc.

As a solvent additive, it is desirable to contain unsaturated carbon-bonded cyclic carbonate. Because a stable coating is formed on the surface of the negative electrode during charging and discharging, the decomposition reaction of the electrolyte can be suppressed. Examples of unsaturated carbon-bonded cyclic carbonates include vinylene carbonate and vinyl vinyl carbonate. In addition, as a solvent additive, it is also desirable to contain sultone (cyclic sulfonate). Because the chemical stability of the battery is improved. Examples of the sultone include propane sultone and propene sultone.

Furthermore, the solvent system preferably contains an acid anhydride. Because the chemical stability of the electrolyte is improved. Examples of the acid anhydride include malonic acid anhydride.

The electrolyte salt may contain, for example, any one or more types of light metal salts such as lithium salts. Examples of the lithium salt include lithium hexafluoride phosphate (LiPF ₆ ) and lithium tetrafluoride borate (LiBF ₄ ). The content of the electrolyte salt is preferably 0.5 mol/kg or more and 2.5 mol/kg or less relative to the solvent. Because of high ion conductivity.

〔Current collector〕

The collector system of the electrode is not particularly limited, such as an electronic conductor that does not cause chemical changes in the lithium ion secondary battery and the electrochemical device, but for example, stainless steel, nickel, aluminum, titanium, sintered carbon, aluminum Or the surface of stainless steel is treated with carbon, nickel, copper, titanium or silver, on the negative electrode In addition to stainless steel, nickel, copper, titanium, aluminum, sintered carbon, etc., Al-Cd alloys, etc. that treat the surface of copper or stainless steel with carbon, nickel, titanium, or silver, etc., can also be used.

〔Isolation film〕

The separator isolates the positive electrode and the negative electrode, and allows lithium ions to pass while preventing current short-circuiting due to contact between the two electrodes. This separation membrane is formed by, for example, a porous membrane composed of synthetic resin or ceramics, and it is also preferable to have a laminated structure in which two or more kinds of porous membranes are laminated. Examples of synthetic resins include polytetrafluoroethylene, polypropylene, and polyethylene.

Next, the electrochemical device according to the present invention will be explained.

The electrochemical device of the present invention is a lithium composite oxide having a negative electrode and a positive electrode. The negative electrode is composed of negative electrode active material particles containing a charge-discharge efficiency of 80% or less when used as a negative electrode active material of an electrochemical device The negative electrode active material layer and the negative electrode current collector are composed of the positive electrode active material layer containing the lithium composite oxide and the positive electrode current collector. In addition, the electrochemical device of the present invention may also be one having a negative electrode and a positive electrode, the negative electrode being composed of a negative electrode active material particle containing silicon oxide containing a composition formula represented by SiO _x (0.5≦x<1.6) The material layer is composed of a negative electrode current collector. The positive electrode is an electrochemical device composed of a positive electrode active material layer containing the lithium composite oxide described above and a positive electrode current collector. In addition, the above-mentioned negative electrode and positive electrode may be a structure not including a current collector. If it is such an electrochemical device, it can be manufactured with low cost while having excellent charge and discharge capacity.

The regenerated lithium composite oxide tends to increase the powder resistance. If the powder resistance increases, the charge and discharge efficiency decreases. Therefore, when using negative electrode active material particles with a charge and discharge efficiency of 80% or less, the charge of the positive electrode and the negative electrode The balance of discharge efficiency is better, and it is ideal to obtain a stable charge and discharge current.

Next, the lithium secondary battery of the present invention will be explained.

The lithium secondary battery of the present invention is one having a negative electrode and a positive electrode, wherein the negative electrode is a negative electrode active material containing negative electrode active material particles having a charge-discharge efficiency of 80% or less when used as a negative electrode active material of a lithium ion secondary battery The layer is composed of a negative electrode current collector, and the positive electrode is composed of a positive electrode active material layer containing the lithium composite oxide described above and a positive electrode current collector. In addition, the lithium secondary battery of the present invention may also have a negative electrode and a positive electrode, wherein the negative electrode is composed of negative electrode active material particles containing silicon oxide represented by a composition formula of SiO _x (0.5≦x<1.6) The negative electrode active material layer and the negative electrode current collector are composed of the positive electrode active material layer containing the above-mentioned lithium composite oxide and the positive electrode current collector. In addition, the above-mentioned negative electrode and positive electrode may be a structure not including a current collector. If it is such a lithium secondary battery, it can have an excellent charge-discharge capacity and can be manufactured at a low cost.

[Examples]

Hereinafter, the present invention will be described more specifically by showing examples, but the present invention is not limited thereto.

(Example 1)

In the coin-type coin battery (CR2032), the lithium composite precursor Li _0.5 CoO _{2 in the} shape of particles that has extracted lithium at a certain current is washed with DMC (dimethyl carbonate), and the lightly crushed powder will be lithium carbonate ( Li ₂ CO ₃ ) is mixed so that the equivalent ratio of Li/Co is 1.00/1.00. After that, the pellets were molded at a pressure of ¹ t/cm ² and sintered in the atmosphere, and then cooled and finely pulverized. A sieve with a pore size of 75 μm is used for classification to produce a lithium composite oxide having a composition of LiCoO ₂ .

(Example 2)

In the electrolytic cell, the lithium composite precursor Li _0.5 CoO _{2 in the} shape of particles that has extracted lithium at a certain current is washed with DMC, and the lightly crushed powder converts lithium carbonate (Li ₂ CO ₃ ) into Li/Co Mix with an equivalent ratio of 1.00/1.00. After that, after sintering in pellet molding at a pressure of ¹ t/cm ² , it is cooled and finely pulverized. A sieve with a pore size of 75 μm is used for classification to produce a lithium composite oxide having a composition of LiCoO ₂ .

(Example 3)

In a coin-shaped coin cell (CR2032), the lithium composite precursor Li _0.5 FePO _{4 in the} shape of particles that has extracted lithium at a certain current is washed with DMC and dried. The lightly crushed powder hydrates lithium hydroxide and monohydrate The salt (LiOH.H ₂ O) is mixed so that the equivalent ratio of Li/Fe is 1.00/1.00. After sintering in a nitrogen atmosphere, it is cooled and finely pulverized. A sieve with a pore size of 75 μm was used for classification to produce a lithium composite oxide having a composition of LiFePO ₄ . The obtained lithium composite oxide LiFePO ₄ system contains 6.5% carbon. This carbon system is contained in the lithium composite precursor Li _0.5 FePO ₄ .

(Example 4)

In the electrolytic cell, the lithium composite precursor Li _0.5 FePO _{4 in the} shape of particles that has extracted lithium at a certain current is washed with DMC, dried, and the lightly crushed powder converts lithium oxalate (COOLi) ₂ to become Li/Fe. Mix with an equivalent ratio of 1.00/1.00. After sintering in nitrogen, it was cooled and finely pulverized. A sieve with a pore size of 75 μm was used for classification to produce a lithium composite oxide having a composition of LiFePO ₄ . The obtained lithium composite oxide LiFePO ₄ system contains 5.5% carbon. This carbon system is contained in the lithium composite precursor Li _0.5 FePO ₄ .

(Example 5)

In a coin-shaped coin battery (CR2032), the lithium composite precursor Li _0.5 Ni _1/3 Co _1/3 Mn _1/3 O _{2 in the} shape of particles that has extracted lithium at a certain current is washed with DMC, dried, and The lightly pulverized powder is mixed with lithium carbonate (Li ₂ CO ₃ ) so that the equivalent ratio of Li/(Ni+Co+Mn) is 1.00/1.00. After sintering in the atmosphere, it is cooled and finely pulverized. A sieve with a pore size of 75 μm was used for classification to produce a lithium composite oxide having a composition of LiNi _1/3 Co _1/3 Mn _1/3 O ₂ .

(Example 6)

In the electrolytic cell, the lithium composite precursor Li _0.5 Ni _1/3 Co _1/3 Mn _1/3 O _{2 in the} shape of particles that have extracted lithium at a certain current is washed with DMC, dried, and lightly crushed powder Lithium hydroxide‧monohydrate salt (LiOH.H ₂ O) was mixed so that the equivalent ratio of Li/(Ni+Co+Mn) was 1.00/1.00. After sintering in the atmosphere, it is cooled and finely pulverized. A sieve with a pore size of 75 μm was used for classification to produce a lithium composite oxide having a composition of LiNi _1/3 Co _1/3 Mn _1/3 O ₂ .

(Example 7)

In the coin-type coin battery (CR2032), the lithium composite precursor Li _0.5 Ni _0.5 Mn _0.3 Co _0.2 O _{2 in the} shape of particles that has extracted lithium at a certain current is washed with DMC, dried, and the lightly crushed powder will Lithium carbonate (Li ₂ CO ₃ ) is mixed so that the equivalent ratio of Li/(Ni+Co+Mn) is 1.00/1.00. After sintering in the atmosphere, it is cooled and finely pulverized. A sieve with a pore size of 75 μm was used for classification to produce a lithium composite oxide having a composition of LiNi _0.5 Mn _0.3 Co _0.2 O ₂ .

(Example 8)

In the electrolytic cell, the lithium composite precursor Li _0.5 Ni _0.5 Mn _0.3 Co _0.2 O _{2 in the} shape of particles that have extracted lithium at a certain current is washed with 1 mol/l LiPF ₆ and DMC, dried, and lightly crushed. The powder mixes lithium carbonate (Li ₂ CO ₃ ) so that the equivalent ratio of Li/(Ni+Co+Mn) is 1.00/1.00. After sintering in the atmosphere, it is cooled and finely pulverized. A sieve with a pore size of 75 μm was used for classification to produce a lithium composite oxide having a composition of LiNi _0.5 Mn _0.3 Co _0.2 O ₂ .

(Example 9)

In a coin-shaped coin cell (CR2032), the lithium composite precursor Li _1.2 V ₂ (PO ₄ ) _{3 in the} shape of particles that has extracted lithium at a certain current is washed with DMC, dried, and hydrogen Lithium oxide and monohydrate salt (LiOH.H ₂ O) are mixed in such a way that the equivalent ratio of Li/V is 1.50/1.00. After sintering in a nitrogen atmosphere, it is cooled and finely pulverized. A sieve with a pore size of 75 μm is used for classification to produce a lithium composite oxide having a composition of Li ₃ V ₂ (PO ₄ ) ₃ . The obtained lithium composite oxide Li ₃ V ₂ (PO ₄ ) ₃ series contains 3.6% carbon. This carbon system is contained in Li _1.2 V ₂ (PO ₄ ) ₃ , which is a lithium composite precursor.

(Example 10)

In the electrolytic cell, the lithium composite precursor Li _1.2 V ₂ (PO ₄ ) _{3 in the} shape of particles that has extracted lithium with a certain current is washed with 1 mol/l LiPF ₆ and DMC, dried, and lightly crushed powder Lithium hydroxide‧monohydrate salt (LiOH.H ₂ O) was mixed so that the equivalent ratio of Li/V was 1.50/1.00. After sintering in a nitrogen atmosphere, it is cooled and finely pulverized. A sieve with a pore size of 75 μm is used for classification to produce a lithium composite oxide having a composition of Li ₃ V ₂ (PO ₄ ) ₃ . The obtained lithium composite oxide Li ₃ V ₂ (PO ₄ ) ₃ series contains 7.1% carbon. This carbon system is contained in Li _1.2 V ₂ (PO ₄ ) ₃ , which is a lithium composite precursor.

(Example 11)

In the coin-type coin battery (CR2032), the lithium composite precursors Li _0.5 Ni _1/3 Co _1/3 Mn _1/3 O ₂ and Li _0.5 CoO _{2 in the} shape of particles that have extracted lithium at a certain current are washed with DMC It is dried, and the lightly pulverized powder is mixed with lithium carbonate (Li ₂ CO ₃ ) so that the equivalent ratio of Li/(Ni+Co+Mn) is 1.00/1.00. After sintering in the atmosphere, it is cooled and finely pulverized. A sieve with a pore size of 75 μm was used for classification to produce a lithium composite oxide having a mixed composition of LiCoO ₂ and LiNi _1/3 Co _1/3 Mn _1/3 O ₂ .

(Example 12)

In the electrolytic cell, the lithium composite precursors Li _0.5 Ni _1/3 Co _1/3 Mn _1/3 O ₂ and Li _0.5 CoO _{2 in the} shape of particles that have extracted lithium at a certain current are washed with DMC and dried. The lightly pulverized powder is mixed with lithium hydroxide‧monohydrate salt (LiOH.H ₂ O) so that the equivalent ratio of Li/(Ni+Co+Mn) is 1.00/1.00. After sintering in the atmosphere, it is cooled and finely pulverized. A sieve with a pore size of 75 μm was used for classification to produce a lithium composite oxide having a mixed composition of LiCoO ₂ and LiNi _1/3 Co _1/3 Mn _1/3 O ₂ .

(Example 13)

In the coin-shaped coin cell (CR2032), the lithium composite precursor Li _0.5 FePO _{4 in the} shape of particles that has extracted lithium at a certain current is washed with DMC and dried, and lithium hydroxide‧monohydrate is added to the lightly crushed powder Salt (LiOH.H ₂ O) and sucrose (sucrose: C ₁₂ H ₂₂ O ₁₁ ). They are mixed so that the equivalent ratio of Li/Fe is 1.00/1.00. After sintering in a nitrogen atmosphere, it is cooled and finely pulverized. A sieve with a pore size of 75 μm was used for classification to produce a lithium composite oxide having a composition of LiFePO ₄ . The obtained lithium composite oxide LiFePO ₄ system contains 5.2% carbon. This carbon is a mixture containing the carbon of the lithium composite precursor Li _0.5 FePO ₄ and the sucrose added during the mixing is reduced, and the carbonized one.

(Example 14)

In a coin-shaped coin cell (CR2032), the lithium composite precursor Li _1.2 V ₂ (PO ₄ ) _{3 in the} shape of particles that has extracted lithium at a certain current is washed with DMC, dried, and mixed with lightly crushed powder to mix hydrogen Lithium oxide‧monohydrate salt (LiOH.H ₂ O) and glucose (glucose: C ₆ H ₁₂ O ₆ ). They were mixed so that the equivalent ratio of Li/V was 1.50/1.00. After sintering in a nitrogen atmosphere, it is cooled and finely pulverized. A sieve with a pore size of 75 μm is used for classification to produce a lithium composite oxide having a composition of Li ₃ V ₂ (PO ₄ ) ₃ . The obtained lithium composite oxide Li ₃ V ₂ (PO ₄ ) ₃ series contains 3.3% carbon. This carbon is a mixture of carbon that is contained in the lithium composite precursor Li _1.2 V ₂ (PO ₄ ) ₃ and glucose added during mixing is reduced, and the carbonized one.

In any of Examples 1-14, the lithium composite oxide having excellent charge and discharge capacity when used as a positive electrode active material of an electrochemical device can be regenerated at a low cost.

However, the present invention is not limited to the above embodiment. Above The embodiments are examples, and anyone having substantially the same structure as the technical idea described in the patent application scope of the present invention and exhibiting the same effect is included in the technical scope of the present invention.

Claims (10)

A method for regenerating a lithium composite oxide, which includes the steps of preparing a lithium composite precursor by electrochemically or chemically partially extracting lithium from the used lithium composite oxide used in one charge and discharge, and The step of reacting the lithium compound with the lithium composite precursor that extracts lithium locally. The method for regenerating a lithium composite oxide according to claim 1, wherein in the step of preparing the lithium composite precursor, the re-dissolution of the lithium composite oxide used after one charge and discharge is not performed, but from The lithium composite oxide used after one charge and discharge is used to extract lithium electrochemically or chemically. The method for regenerating a lithium composite oxide according to claim 1 or 2, wherein the step of reacting includes the step of sintering the lithium composite precursor that locally extracts lithium and the lithium compound to react . The method for regenerating a lithium composite oxide according to claim 1 or 2, wherein the step of causing the reaction includes the step of mixing the lithium composite precursor that locally extracts lithium with the lithium compound to perform a hydrothermal reaction . The method for regenerating a lithium composite oxide according to claim 1 or 2, wherein the aforementioned lithium composite precursor for partial extraction of lithium is a composite oxide represented by the following general formula (1): Li _1-x Co _1-z M _z O ₂ (0<x<1, 0≦z<1)‧‧‧‧(1) (In the formula, M is represented by Mn, Ni, Fe, V, Cr, Al, Nb, Ti, Cu, Zn One or more metal elements are selected from the group), and the lithium composite oxide obtained by the above reaction step is a lithium cobalt composite oxide represented by the following general formula (2): Li _1-y Co _{1- z} M _z O ₂ (0≦y<x, 0≦z<1) ‧‧‧(2) (where M is represented by Mn, Ni, Fe, V, Cr, Al, Nb, Ti, Cu, One or more metal elements are selected from the group of Zn). The method for regenerating a lithium composite oxide according to claim 1 or 2, wherein the lithium composite precursor for extracting lithium locally is a lithium iron phosphorous composite oxide represented by the following general formula (3): Li _1-x Fe _1-z M _z PO ₄ (0<x<1, 0≦z<1) ‧‧‧ (3) (where M is represented by Co, Mn, Ni, V, Cr, Al, Nb, Ti, One or more metal elements are selected from the group of Cu and Zn), and the lithium composite oxide obtained by the aforementioned reaction step is a lithium iron phosphorus composite oxide represented by the following general formula (4): Li _{1 -y} Fe _1-z M _z PO ₄ (0≦y<x, 0≦z<1) ‧‧‧ (4) (where M is represented by Co, Mn, Ni, V, Cr, Al, Nb , Ti, Cu, Zn select one or more metal elements). The method for regenerating a lithium composite oxide according to claim 1 or 2, wherein the aforementioned lithium composite precursor for partial extraction of lithium is a lithium vanadium-phosphorus composite oxide represented by the following general formula (5): Li _3-x V _2-z M _z (PO ₄ ) ₃ (0<x<3, 0≦z<2) ‧‧‧(5) (where M is represented by Co, Mn, Ni, Fe, Cr, Al, Nb , Ti, Cu, Zn select one or more metal elements), the lithium composite oxide obtained by the above reaction step is a lithium vanadium phosphorus composite oxide represented by the following general formula (6) ：Li _3-y V _2-z M _z (PO ₄ ) ₃ (0≦y<x, 0≦z<2) ‧‧‧ (6) (where M is represented by Co, Mn, Ni, Fe , Cr, Al, Nb, Ti, Cu, Zn, select one or more metal elements). The method for regenerating a lithium composite oxide according to claim 1 or 2, wherein, as the foregoing lithium composite precursor, two or more lithium composite precursors are used. The method for regenerating a lithium composite oxide according to claim 1 or 2, wherein the lithium composite precursor contains carbon as the lithium composite precursor, and the lithium composite oxide obtained by the reaction step includes the lithium composite precursor Contains carbon. The method for regenerating a lithium composite oxide according to claim 1 or 2, wherein the step of reacting includes the step of reacting the lithium composite precursor with a carbon compound, and the lithium compound obtained by the step of reacting The oxide system contains carbon.

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