JP6511761B2 - Method of producing coated composite oxide particles for positive electrode active material for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery using coated composite oxide particles produced by the method - Google Patents

Description

  The present invention provides a coated composite oxide particle for a positive electrode active material for a non-aqueous electrolyte secondary battery, a method for producing the same, and gelation when the coated composite oxide particle for the positive electrode active material is used as a positive electrode material. On how to prevent it.

  In recent years, with the spread of mobile electronic devices such as mobile phones and notebook computers, development of a small and lightweight non-aqueous electrolyte secondary battery having high energy density is strongly desired. In addition, development of a high-output secondary battery as a large battery for a motor drive power source or the like is strongly desired.

  There is a lithium ion secondary battery as a secondary battery which satisfies such a demand. The lithium ion secondary battery is composed of a negative electrode, a positive electrode, an electrolytic solution and the like, and a material capable of desorbing and inserting lithium is used as an active material of the negative electrode and the positive electrode.

  With regard to lithium ion secondary batteries, research and development are being actively carried out at present. Among them, lithium ion secondary batteries using a layered or spinel type lithium metal composite oxide as a positive electrode material are 4V class The high voltage density is obtained, and the practical use is advanced as a battery having a high energy density.

Lithium cobalt complex oxide (LiCoO ₂ ), which is relatively easy to synthesize at present, lithium nickel complex oxide (LiNiO ₂ ) using nickel which is cheaper than cobalt, as an active material of positive electrode of lithium ion secondary battery Lithium nickel cobalt manganese complex oxide (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ), lithium manganese complex oxide using manganese (LiMn ₂ O ₄ ), lithium nickel manganese complex oxide (LiNi _{. 5} Mn _0.5 O _2), lithium-rich nickel-cobalt-manganese composite oxide _{(Li 2 MnO 3 -LiNi x Mn} y Co z O 2) lithium composite oxide or the like is proposed.

For example, lithium-rich nickel-cobalt-manganese composite oxide _{(Li 2 MnO 3 -LiNi x Mn} y Co z O 2) has attracted attention from the viewpoint of excellent thermal stability at high capacity. Lithium excess nickel cobalt manganese complex oxide is a layered compound like lithium cobalt complex oxide, lithium nickel complex oxide, etc. (refer nonpatent literature 1).

In addition, lithium nickel composite oxide (LiNiO ₂ ) using nickel, which is cheaper than cobalt, is drawing attention from the viewpoint of higher discharge capacity, low cost of raw materials, and stable supply.

  However, the gelation of the paste which is a mixture of these positive electrode active materials with the binder and the conductive material becomes a problem. The gelation of a paste refers to a state in which the flowability and uniformity thereof are lost due to an increase in viscosity, and when gelation progresses excessively, coating on a current collector becomes impossible. In addition, even if it is a slight gelation, it greatly contributes to the resistance value and the like of the prepared electrode sheet, and the battery characteristics such as the discharge capacity, the current density dependency, and the low temperature characteristics are degraded. The prevention of gelation has been a serious problem to be solved in electrode production.

  Therefore, measures to prevent gelation of the active material of the positive electrode of the lithium ion secondary battery have become important issues.

  In this regard, Patent Document 1 includes an electrode mixture (positive electrode paste) to which an acid is added, in addition to a binder (binding agent) comprising a vinylidene fluoride polymer and a powder electrode material such as positive electrode active material particles. ing. However, in the case of the electrode mixture (positive electrode paste) of Patent Document 1, after application, it is dried, and when it is used in a battery as a positive electrode active material layer, the anion derived from the added acid is in the electrolyte of the battery. There is a problem of elution and deterioration of battery characteristics.

  Patent Document 2 discloses an active material in which a zirconia sol solution is sprayed onto a powder such as lithium cobaltate to cover the entire surface with zirconia. This is because zirconia prevents deterioration of the active material and improves cycle characteristics. However, since zirconia covers the entire surface of the active material, the diffusion rate of lithium ions is decreased, which makes it difficult to insert and release lithium ions, or makes it difficult to move lithium ions. As a result, there is a problem that the output characteristics of the lithium secondary battery are degraded.

  On the other hand, Patent Document 3 discloses an active material in which a part of the surface of the active material is coated with metal by mixing a LiMnO-based active material in a metal alkoxide solution and baking it. This is to improve the cycle characteristics by suppressing the reactivity between the active material and the electrolytic solution by partially covering the surface of the active material. However, since the metal coating is a part of the surface of the active material, there is a problem that the deterioration of the active material and the electrolyte due to the reaction between the active material and the electrolyte is not sufficiently suppressed and sufficient cycle characteristics can not be obtained. The

Patent 3540080 gazette Unexamined-Japanese-Patent No. 2006-156032 JP 2005-78800 A

FB Technical News, No. 66, 2011.1

  The present invention has been made based on such findings, and the object of the present invention is to use a positive electrode active material for a non-aqueous electrolyte secondary battery of a lithium ion secondary battery which is susceptible to gelation. An object of the present invention is to provide a method for producing coated composite oxide particles for a positive electrode active material for a non-aqueous electrolyte secondary battery.

  The present inventors conducted extensive research to solve the problems of the prior art described above, and as a result, in the method of producing complex oxide particles, a step of coating CMC (carboxymethyl cellulose) is added to form coated complex oxide particles. Thus, the present inventors have found that it is possible to prevent gelation of a paste which is a mixture of a positive electrode active material for a non-aqueous electrolyte secondary battery, and a binder and a conductive material thereof, and the present invention has been completed.

That is, according to the first aspect of the present invention, a composite oxide particle is obtained by mixing the above-mentioned heat-treated particle with lithium and / or a lithium compound and heat-treating the mixed hydroxide particle to obtain heat-treated particle. In the non-reductive gas atmosphere, the amount of carboxymethylcellulose attached to the composite oxide particles is made 0.005 wt% or more and 1.0 wt% or less by mixing the composite oxide particles and the carboxymethylcellulose solution in the firing step. Or a coating step of obtaining coated composite oxide particles by leaving at 100 ° C. to 300 ° C. in a vacuum atmosphere, and a method for producing coated composite oxide particles for a positive electrode active material for a non-aqueous electrolyte secondary battery It is.

A second aspect of the present invention is that the composite hydroxide particles are nickel-cobalt-manganese composite hydroxide particles, and the composite oxide particles are represented by the following general formula (1): lithium excess nickel-cobalt-manganese composite oxide It is a manufacturing method of the covering complex oxide particles given in the first invention which is particles.
bLi ₂ MnO ₃ · (1-b) Li _{1 + u} Ni _x Co _y Mn _z M _t O ₂ (1)
(Wherein, 0.2 ≦ b ≦ 0.8, −0.05 ≦ u ≦ 0.20, x + y + z + t = 1, 0.1 ≦ x ≦ 0.4, 0.2 ≦ y ≦ 0.8, 0 1 ≦ z ≦ 0.4, 0 ≦ t ≦ 0.1, M is an additive element, and at least one selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, W The above elements.)

The third aspect of the present invention, the a composite hydroxide particles crab nickel composite hydroxide particles, wherein the composite oxide particles is a lithium nickel composite oxide particles represented by the following general formula (2) the It is a manufacturing method of the coated complex oxide particle as described in one invention.
Lix Ni _1-y-z Co _{y M z} O ₂ (2)
(Wherein, 0.85 ≦ x ≦ 1.25, 0 <y ≦ 0.5, 0 ≦ z ≦ 0.5, 0 <y + z ≦ 0.75, and the element Me is Al, Mg, Nb, Mn And at least one element selected from the group consisting of Ti and Ca)

  In the fourth aspect of the present invention, the concentration of Na contained in the composite hydroxide particles is 0.2% by weight or more and 1.0% by weight or less, and mixed in a ratio of 5 g of the composite hydroxide particles to 100 ml of water. It is a manufacturing method of the covering complex oxide particles according to any one of the first to third inventions, wherein the pH of the obtained slurry is 11.0 or more at 25 ° C.

  5th of this invention is a manufacturing method of the coated complex oxide particle as described in any one of 1st to 4th invention which performs the said heat processing process at 500 degreeC or more and 750 degrees C or less.

  The sixth of the present invention is a non-aqueous electrolyte secondary battery using coated composite oxide particles produced by the method of producing coated composite oxide particles according to any of the first to fifth inventions.

  According to the present invention, the positive electrode active material can prevent gelation by forming a CMC (carboxymethyl cellulose) coating layer on the surface of the composite oxide. Therefore, the non-aqueous secondary battery composed of the positive electrode containing the positive electrode active material has excellent battery characteristics and can suppress the defect rate to a low level, and its industrial value is extremely large.

FIG. 1 is a TEM observation image (observation scale 100 nm) of the lithium-rich nickel cobalt manganese composite oxide of the present invention.

  Hereinafter, the method for producing the coated composite oxide particles of the present invention will be described in detail. The invention is not limited to the embodiments described below.

<Compound oxide>
The composite oxide powder of the present invention is not particularly limited as long as it can be used as an active material of a positive electrode of a lithium ion secondary battery. For example, lithium cobalt composite oxide (LiCoO ₂ ), lithium nickel composite oxide (LiNiO ₂ ), lithium nickel cobalt manganese composite oxide (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ), manganese are used. Lithium manganese complex oxide (LiMn ₂ O ₄ ), lithium nickel manganese complex oxide (LiNi _0.5 Mn _0.5 O ₂ ), lithium excess nickel cobalt manganese complex oxide (Li ₂ MnO ₃ -LiNi _x Mn _y Co _z O ₂ ) etc. can be mentioned.

[Lithium excess nickel cobalt manganese complex oxide]
The lithium excess nickel cobalt manganese composite oxide of the present embodiment is a composite oxide represented by the general formula (1).

bLi ₂ MnO ₃ · (1-b) Li _{1 + u} Ni _x Co _y Mn _z M _t O ₂ (1)
(0.2 ≦ b ≦ 0.8, −0.05 ≦ u ≦ 0.20, x + y + z + t = 1, 0.1 ≦ x ≦ 0.4, 0.2 ≦ y ≦ 0.8, 0.1 ≦ z ≦ 0.4, 0 ≦ t ≦ 0.1, M is an additive element, and is one or more elements selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, W)

  When u is less than -0.05, the reaction resistance of the positive electrode in the non-aqueous electrolyte secondary battery using the obtained positive electrode active material for the non-aqueous electrolyte secondary battery increases, and the output of the battery decreases. . On the other hand, when u exceeds 0.20, while the initial stage discharge capacity at the time of using the said positive electrode active material for the positive electrode of a battery falls, the reaction resistance of a positive electrode will also increase. Therefore, u is preferably set to −0.05 or more and 0.20 or less and preferably set to 0.05 or more and 0.15 or less in order to further reduce the reaction resistance.

  Further, as represented by the general formula (1), the positive electrode active material for a non-aqueous electrolyte secondary battery of the present embodiment is adjusted so that the lithium-excess nickel-cobalt-manganese composite oxide particles contain an additive element. Is more preferable. By containing the above-described additive element, it is possible to improve the durability and output characteristics of a battery using this as a positive electrode active material for a non-aqueous electrolyte secondary battery.

  In particular, by uniformly distributing the additive element on the surface or in the inside of the particle, the above effect can be obtained in the whole particle, and the above effect can be obtained and the reduction of the capacity can be suppressed by adding a small amount. Furthermore, in order to obtain an effect with a smaller addition amount, it is preferable to increase the concentration of the additive element at the particle surface rather than inside the particle.

  When the atomic ratio t of the additive element M to all the atoms exceeds 0.1, the metal element contributing to the reduction reaction is reduced, and the battery capacity is unfavorably reduced. Therefore, the additive element M is adjusted to be 0 or more and 0.1 or less at the above atomic ratio t.

  The average particle diameter of the active material is preferably in the range of 2.0 μm to 8.0 μm. When the average particle size is less than 2 μm, the packing density of the particles decreases when the positive electrode is formed, and the battery capacity per volume of the positive electrode decreases. On the other hand, when the average particle diameter exceeds 8.0 m, the specific surface area of the positive electrode active material for non-aqueous electrolyte secondary battery decreases, and the interface with the battery electrolyte decreases, so the resistance of the positive electrode increases. As a result, the output characteristics of the battery are degraded.

  Therefore, if the average particle diameter is adjusted to be 2.0 μm or more and 8.0 μm or less, preferably 3.0 μm or more and 8.0 μm or less, more preferably 3.0 μm or more and 6.5 μm or less, this nonaqueous electrolyte A battery using a positive electrode active material for a secondary battery as a positive electrode can increase battery capacity per volume, and can obtain battery characteristics excellent in high safety, high output, and the like.

  Identification of the structure and composition of the above lithium-rich nickel-cobalt-manganese composite oxide can be made by X-ray diffraction (XRD), electron diffraction, emission spectroscopy (ICP) or the like. Further, in a high resolution image using a high resolution transmission electron microscope (TEM), even if the sample is a relatively large particle, the layer structure can be observed by micro-processing the sample.

[Lithium nickel complex oxide]
The lithium-nickel composite oxide powder of the present embodiment is a composite oxide represented by the general formula (2).

Li _x Ni _1-y-z Co _{y M z} O ₂ (2)
(Wherein, 0.85 ≦ x ≦ 1.25, 0 <y ≦ 0.5, 0 ≦ z ≦ 0.5, 0 <y + z ≦ 0.75, and the element Me is Al, Mg, Nb, Mn And at least one selected from the group consisting of Ti and Ca.)

  Identification of the structure and composition of the above lithium nickel composite oxide can be made by X-ray diffraction (XRD), electron beam diffraction, emission spectroscopy (ICP), and the like. Further, in a high resolution image using a high resolution transmission electron microscope (TEM), even if the sample is a relatively large particle, the layer structure can be observed by micro-processing the sample.

<Method of producing coated complex oxide particles>
In the method for producing coated composite oxide particles according to the present embodiment, a) a heat treatment step of heating the composite hydroxide particles to obtain heat treated particles; b) mixing the heat treated particles with lithium or / and a lithium compound and firing And c) mixing the composite oxide particles with a solution of CMC (carboxymethyl cellulose) to obtain a composite oxide particle, and the adhesion amount of carboxymethyl cellulose of the composite oxide particle is not less than 0.005% by weight. And a coating step of obtaining coated composite oxide particles by leaving the mixture at a temperature of 100 ° C. or more and 300 ° C. or less in a non-reducing gas or vacuum atmosphere. Each step will be described below.

a) Heat treatment process A heat treatment process is a process of heating and heat-treating composite hydroxide particles, and is a process of removing moisture contained in composite hydroxide particles. By performing this heat treatment step, it is possible to reduce the amount of water remaining in the composite hydroxide particles up to the firing step to a certain amount. This can prevent variation in the ratio of the number of atoms of the metal and the number of atoms of the lithium in the resulting coated composite oxide particles.

  In the heat treatment step, water may be removed to such an extent that the ratio of the number of metal atoms of the composite hydroxide particles and the number of lithium atoms does not vary. The heating temperature is preferably 100 ° C. or more and 750 ° C. or less, and more preferably 500 ° C. or more and 750 ° C. or less. When the heating temperature is less than 100 ° C., excess water in the composite hydroxide particles can not be removed, and it tends to be difficult to suppress the above-mentioned variation. On the other hand, when the heating temperature exceeds 750 ° C., it tends to be difficult to sinter the particles by heat treatment to obtain composite oxide particles having a uniform particle diameter.

  Further, by setting the heating temperature to 500 ° C. or more, all of the composite hydroxide particles can be converted to composite oxide particles, which is further preferable. In addition, the said dispersion | variation can be suppressed by calculating | requiring beforehand the metal component contained in the composite hydroxide particle by heat processing conditions by analysis, and determining a ratio with a lithium compound.

  The atmosphere in which the heat treatment is performed is not particularly limited, as long as it is a non-reducing atmosphere, but is preferably performed in an air stream that can be easily performed.

  The heat treatment time is not particularly limited, but excess water removal of the composite hydroxide particles may not be sufficiently performed in less than 1 hour, so at least 1 hour or more is preferable, and 5 hours or more and 15 hours or less More preferable.

  The equipment used for the heat treatment is not particularly limited, as long as the composite hydroxide particles can be heated in a non-reducing atmosphere, preferably in an air stream, and there is no gas generation in the electric furnace Etc. are preferably used.

b) Firing Step The firing step is a step of obtaining composite oxide particles by mixing heat-treated particles and lithium and / or lithium compound and firing.

  Here, the heat-treated particles include not only composite hydroxide particles from which residual water has been removed in the heat treatment step, but also composite oxide particles converted into oxides in the hydroxide particle heat treatment step or mixed particles thereof. Be

(mixture)
The heat-treated particles and lithium or / and lithium compound have the number of atoms of metals other than lithium, that is, the ratio of the sum of the number of atoms of nickel, cobalt, manganese and the additive element (Me) to the number of atoms of lithium (Li) It is preferable to mix so that (Li / Me) becomes 1.2 or more and 1.8 or less, preferably 1.4 or more and 1.6 or less. That is, since Li / Me does not change before and after the firing step described later, Li / Me mixed in this mixing step becomes Li / Me in the positive electrode active material for non-aqueous electrolyte secondary batteries, so Li / Me in the lithium mixture Are mixed to be the same as Li / Me in the positive electrode active material for a non-aqueous electrolyte secondary battery to be obtained.

  The lithium compound is not particularly limited, but for example, lithium hydroxide, lithium nitrate, lithium carbonate, or a mixture thereof is preferable in that it is easily available. In particular, lithium hydroxide or lithium carbonate is more preferably used in consideration of ease of handling and stability of quality. In the case where the target composite oxide particles are lithium nickel composite oxide particles represented by the general formula (2), it is preferable to use lithium hydroxide.

  In addition, it is preferable to mix sufficiently before baking. If mixing is not sufficient, Li / Me may vary among individual particles, which may cause problems such as when sufficient battery characteristics can not be obtained.

  In addition, general mixers can be used for mixing, and for example, shaker mixers, Loedige mixers, Julia mixers, V blenders, etc. can be used, and complex oxidation can be performed to the extent that heat treatment particles etc. are not destroyed. The substance particles and the substance containing lithium may be sufficiently mixed.

(Firing)
This step is a step of calcining the above mixture to obtain composite oxide particles. By calcining the lithium mixture, lithium contained in the lithium mixture diffuses into the heat-treated particles to form composite oxide particles.

((Firing temperature))
The firing temperature is preferably determined by the target composite oxide particles. For example, in the case where the target composite oxide particle is a lithium-rich nickel-cobalt-manganese composite oxide particle represented by the general formula (1), it is preferably performed at 850 ° C. or more and 1050 ° C. or less, 900 ° C. or more It is more preferable to carry out at 1000 ° C. or less. When the firing temperature is less than 850 ° C., the diffusion of lithium into the heat-treated particles is not sufficiently carried out, and surplus lithium and unreacted particles remain, or the crystal structure is not sufficiently prepared, which is used for batteries In such a case, it tends to be difficult to obtain sufficient battery characteristics. If the firing temperature exceeds 1050 ° C., sintering may occur violently between the composite oxide particles and abnormal particle growth may occur. For this reason, the particles after firing become coarse and particle morphology (spherical shape described later) It tends to be impossible to retain the form of secondary particles. Such a coated composite oxide particle has a reduced specific surface area, and therefore, when used in a battery, there arises a problem that the resistance of the positive electrode is increased and the battery capacity is reduced.

  Moreover, when the composite oxide particle which is a target object is a lithium nickel composite oxide particle represented by General formula (2), it is preferable to carry out at 600 degreeC or more and 800 degrees C or less, and 730 degrees C or more and 760 degrees C or less More preferably,

  From the viewpoint of uniformly performing the reaction between the heat-treated particles and the lithium compound, the temperature is preferably raised to the above temperature by setting the temperature rising rate to 3 ° C./min or more and 10 ° C./min or less. Furthermore, the reaction can be performed more uniformly by maintaining the temperature around the melting point of the lithium compound for about 1 hour to 5 hours.

((Firing time))
The firing time is preferably determined by the target composite oxide particles. For example, in the case where the composite oxide particles are lithium-rich nickel cobalt manganese composite oxide particles represented by the general formula (1), the holding time is preferably at least 2 hours or more, more preferably 4 More than 24 hours. If it is less than 2 hours, complex oxide may not be sufficiently formed. In the case where the target composite oxide particles are lithium-nickel composite oxide particles represented by the general formula (2), the holding time is preferably at least 1 hour or more, more preferably, 10 hours or more and 24 hours or less. If it is less than one hour, the formation of the complex oxide may not be sufficiently performed.

  After the holding time, although not particularly limited, when the mixture is loaded in a mortar and fired, the descent speed is set to 2 ° C./min or more and 10 ° C./min or less in order to suppress deterioration of the mortar. Preferably, the atmosphere is cooled to 200 ° C. or less.

(Pre-baking process)
In particular, when lithium hydroxide or lithium carbonate is used as the lithium compound, it is preferable to further include a pre-baking step before firing. The firing temperature in the pre-firing step is preferably a reaction temperature of lithium hydroxide or lithium carbonate and heat treatment particles. That is, as for the calcination temperature in a temporary calcination process, 350 degreeC or more and 800 degrees C or less are preferable, More preferably, they are 450 degreeC or more and 780 degrees C or less. In addition, the baking time in the pre-baking step is about 1 hour to 10 hours, preferably 3 hours to 6 hours. By maintaining lithium hydroxide or lithium carbonate at around the above reaction temperature, the diffusion of lithium to the heat-treated particles can be sufficiently facilitated, so that more uniform composite oxide particles can be obtained.

  When it is desired to increase the concentration of the additive element on the surface of the composite oxide particle, it is sufficient to use, as the heat treatment particle which is a raw material, one having the particle surface uniformly coated with the additive element. By baking the lithium mixture containing such heat-treated particles under appropriate conditions, the concentration of the additive element on the surface of the composite oxide particles can be increased. More specifically, if a lithium mixture containing composite hydroxide particles coated with an additive element is fired at a low firing temperature and a short firing time, the concentration of the additive element M on the particle surface is increased. Complex oxide particles can be obtained.

  And, even when the lithium mixture containing the composite hydroxide particles coated with the additive element is fired, if the firing temperature is increased and the firing time is extended, the composite oxide particles in which the additive element is uniformly distributed in the particles You can get That is, by adjusting the heat treatment particles used as the raw materials and the firing conditions, oxide particles having the target concentration distribution can be obtained.

((Firing atmosphere))
The atmosphere at the time of firing is preferably an oxidative atmosphere, more preferably an oxygen concentration of 18% by volume to 100% by volume, and particularly preferably a mixed atmosphere of oxygen and an inert gas. preferable. That is, the firing is preferably performed in the air or an oxygen stream. If the oxygen concentration is less than 18% by volume, the crystallinity of the lithium-rich nickel cobalt manganese composite oxide may not be sufficient. In particular, in consideration of the battery characteristics, it is preferable to carry out in an oxygen stream.

  The furnace used for the firing is not particularly limited as long as it can heat the lithium mixture in the atmosphere or an oxygen stream, but there is no gas generation from the viewpoint of keeping the atmosphere in the furnace uniform. Electric furnaces are preferred, and either batch or continuous furnaces can be used.

(Crushing)
The composite oxide particles obtained by firing may have aggregation or slight sintering. In this case, it may be crushed, whereby composite oxide particles can be obtained. In addition, with crushing, mechanical energy is injected into an aggregate consisting of a plurality of secondary particles generated by sintering necking between secondary particles at the time of firing, and the secondary particles themselves are hardly broken. It is an operation to separate secondary particles and loosen aggregates.

c) Coating step In the coating step, the composite oxide particles and the CMC (carboxymethyl cellulose) solution are mixed to make the carboxymethyl cellulose adhesion amount of the composite oxide particles 0.005% to 1.0% by weight , This is a step of obtaining coated composite oxide particles by leaving at 100 ° C. or more and 300 ° C. or less in a non-reducing gas or vacuum atmosphere. The present invention can provide composite oxide particles for a positive electrode active material for a non-aqueous electrolyte secondary battery excellent in air stability early by adding a coating step after the above-mentioned firing step. As a result, the subsequent steps can be performed under the atmosphere, and the expensive installation and running costs for maintaining the manufacturing environment are not increased. Therefore, the present invention is a production method with extremely high productivity.

  The composite oxide particles can be coated with CMC (carboxymethylcellulose) by contacting the composite oxide particles with CMC (carboxymethylcellulose) in a CMC (carboxymethylcellulose) solution. This is because the hydroxyl groups present in the cellulose skeleton contained in CMC (carboxymethylcellulose) are coated on the entire surface of the composite oxide particles by hydrogen bonding with the composite oxide particles. Since the composite oxide particles can be coated by such a simple method, the production method is extremely high.

  In addition, the concentration of the impurity is 0.2 wt% or more and 1.0 wt% or less, and the pH of the slurry mixed at a ratio of 5 g of the active material to 100 ml of pure water is 11.0 or more at 25 ° C. In the case of a composite oxide particle for a positive electrode active material for an aqueous electrolyte secondary battery, the effect of the CMC (carboxymethyl cellulose) coating of the present invention is very highly exhibited. This is because complex oxide particles having a high Na concentration of 0.2% by weight or more exhibit the above pH of 11.0 or more, thereby causing gelation at the time of preparation of a slurry for coating a positive electrode, but the alkali component at this time The effect is to suppress the elution of Na. Therefore, the present invention is particularly effective when the lithium excess nickel cobalt manganese composite oxide containing Na as an impurity is used as a positive electrode active material for a non-aqueous electrolyte secondary battery.

(Remove solvent)
In this embodiment, the solvent in the CMC (carboxymethyl cellulose) mixed solution is removed by mixing with the CMC (carboxymethyl cellulose) solution and leaving it at 100 ° C. or more and 300 ° C. or less under a non-reducing gas or vacuum atmosphere. The non-reducing gas refers to a non-reducing gas such as air, oxygen, argon or nitrogen. The solvent contained in the coated composite oxide particles can be removed by heating at 100 ° C. or more and 300 ° C. or less in a non-reducing gas or vacuum atmosphere and drying. By performing the reaction under a non-reducing gas or a vacuum atmosphere, the composite oxide particles do not cause a reduction reaction. The heating temperature is 100 ° C. or more and 300 ° C. or less, preferably 100 ° C. or more and 280 ° C. If it is less than 100 ° C., it tends to be difficult to remove the solvent, and if it exceeds 300 ° C., it is not preferable because CMC (carboxymethyl cellulose) may be decomposed. The heating time is preferably 1 hour or more.

<Secondary battery production>
The positive electrode active material for a non-aqueous electrolyte secondary battery manufactured using the above-described coated composite hydroxide particles can obtain a high initial discharge capacity of 250 mAh / g or more, for example, when used as a positive electrode of a 2032 type coin battery It exhibits excellent characteristics as a positive electrode active material for non-aqueous electrolyte secondary batteries.

  The non-aqueous electrolyte secondary battery employs a positive electrode using the above-mentioned positive electrode active material for non-aqueous electrolyte secondary battery as a positive electrode material. First, the structure of the non-aqueous electrolyte secondary battery of the present embodiment will be described.

  The non-aqueous electrolyte secondary battery of the present embodiment has substantially the same structure as a general non-aqueous electrolyte secondary battery except that the above coated composite hydroxide particles are used.

  Specifically, the non-aqueous electrolyte secondary battery of the present embodiment has a structure including a case, and a positive electrode, a negative electrode, a non-aqueous electrolytic solution, and a separator housed in the case. More specifically, the positive electrode and the negative electrode are stacked via the separator to form an electrode assembly, and the obtained electrode assembly is impregnated with the non-aqueous electrolytic solution, and the positive electrode current collector of the positive electrode and the positive electrode terminal passing outside Between the negative electrode current collector of the negative electrode and the negative electrode terminal leading to the outside, respectively, using a current collection lead or the like, and by sealing in a case, the secondary non-aqueous electrolyte of this embodiment A battery is formed.

  Needless to say, the structure of the non-aqueous electrolyte secondary battery of the present embodiment is not limited to the above example, and the outer shape thereof can adopt various shapes such as a cylindrical shape or a laminated shape.

(Positive electrode)
First, the positive electrode which is the feature of the non-aqueous electrolyte secondary battery of the present embodiment will be described. The positive electrode is a sheet-like member, and is formed by applying and drying a positive electrode mixture paste containing the positive electrode active material for a non-aqueous electrolyte secondary battery of this embodiment, for example, on the surface of a current collector made of aluminum foil. It is done.

  In addition, a positive electrode is suitably processed according to the battery to be used. For example, a cutting process is performed to form an appropriate size according to a target battery, and a pressure compression process using a roll press or the like is performed to increase the electrode density.

  The positive electrode mixture paste is formed by adding a solvent to the positive electrode mixture and kneading. The positive electrode mixture is formed by mixing the positive electrode active material for a non-aqueous electrolyte secondary battery of the present embodiment, which is powdery, with a conductive material and a binder.

  The conductive material is added to provide the electrode with appropriate conductivity. The conductive material is not particularly limited, and, for example, carbon black-based materials such as graphite (natural graphite, artificial graphite, expanded graphite and the like) and acetylene black and ketjen black can be used.

  The binder plays a role of holding the coated composite hydroxide particles. The binder used in the positive electrode mixture is not particularly limited, and examples thereof include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), fluororubber, ethylene propylene diene rubber, styrene butadiene, cellulose resin, Polyacrylic acid or the like can be used.

  Activated carbon or the like may be added to the positive electrode mixture, and the electric double layer capacity of the positive electrode can be increased by adding activated carbon or the like.

  The solvent dissolves the binder and disperses the positive electrode active material for non-aqueous electrolyte secondary battery, the conductive material, the activated carbon and the like in the binder. Although this solvent is not particularly limited, for example, an organic solvent such as N-methyl-2-pyrrolidone can be used.

  Moreover, the mixing ratio of each substance in the positive electrode mixture paste is not particularly limited. For example, when the solid content of the positive electrode mixture excluding the solvent is 100 parts by mass, the content of the positive electrode active material for a non-aqueous electrolyte secondary battery is 60 parts by mass similarly to the positive electrode of a general non-aqueous electrolyte secondary battery The content of the conductive material can be made 1 to 20 parts by mass, and the content of the binder can be made 1 to 20 parts by mass.

(Negative electrode)
The negative electrode is a sheet-like member formed by applying a negative electrode mixture paste onto the surface of a metal foil current collector such as copper and drying. This negative electrode is formed by substantially the same method as that of the positive electrode although the components constituting the negative electrode mixture paste and the composition thereof, the material of the current collector, etc. are different, and various treatments may be carried out as required. Is done.

  The negative electrode mixture paste is obtained by adding a suitable solvent to a negative electrode mixture obtained by mixing a negative electrode active material and a binder to form a paste.

  As the negative electrode active material, for example, a lithium-containing substance such as metal lithium or a lithium alloy, or an occluding substance capable of occluding and desorbing lithium ions can be adopted.

  The occluding substance is not particularly limited, and, for example, natural graphite, artificial graphite, an organic compound sintered body such as a phenol resin, and a powdery substance of a carbon substance such as coke can be used. When such an occluding material is employed as a negative electrode active material, a fluorine-containing resin such as PVDF can be used as a binder as with the positive electrode, and as a solvent for dispersing the negative electrode active material in the binder, Organic solvents such as N-methyl-2-pyrrolidone can be used.

(Separator)
The separator is disposed between the positive electrode and the negative electrode, and has a function of separating the positive electrode and the negative electrode and holding an electrolyte. Such a separator is, for example, a thin film such as polyethylene or polypropylene, and a film having a large number of fine pores can be used, but it is not particularly limited as long as it has the above-mentioned function.

(Non-aqueous electrolyte solution)
The non-aqueous electrolytic solution is one in which a lithium salt as a support salt is dissolved in an organic solvent.

  Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate and trifluoropropylene carbonate; and linear carbonates such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate and dipropyl carbonate; Ether compounds such as methyltetrahydrofuran and dimethoxyethane; sulfur compounds such as ethyl methyl sulfone and butanesultone; and phosphorus compounds such as triethyl phosphate and trioctyl phosphate alone or in combination of two or more. , Can be used.

As the supporting salt, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiN (CF ₃ SO ₂ ) ₂ , and complex salts thereof can be used. The non-aqueous electrolytic solution may contain a radical scavenger, a surfactant, a flame retardant, and the like to improve the battery characteristics.

(Characteristics of non-aqueous electrolyte secondary battery of the present embodiment)
The non-aqueous electrolyte secondary battery of the present embodiment has the above configuration, and has the positive electrode using the coated composite oxide particles of the present embodiment, so high initial discharge capacity and low positive electrode resistance can be obtained. The capacity is high output. In particular, the lithium-rich nickel-cobalt-manganese composite oxide is higher in thermal stability and superior in safety as compared with other lithium nickel-based oxides for positive electrode active materials for non-aqueous electrolyte secondary batteries. It can be said.

(Use of secondary battery of this embodiment)
Since the non-aqueous electrolyte secondary battery of the present embodiment has the above-mentioned properties, it is suitable for the power supply of small portable electronic devices such as a notebook personal computer and a portable telephone terminal which always require a high capacity.

  The secondary battery of the present embodiment is also suitable for a battery as a power source for driving a motor required for an electric vehicle. If the size of the battery is increased, it is difficult to ensure safety, and an expensive protective circuit is indispensable. However, the non-aqueous electrolyte secondary battery of the present embodiment has excellent safety, so safety Not only is it easy to ensure the quality, but expensive protection circuits can be simplified and made more inexpensive. And since size reduction and high output-ization are possible, it is suitable as a power supply for transportation apparatus which receives restrictions in mounting space.

<Method of gelation test>
9.5 g of a coated composite oxide powder coated with CMC (carboxymethyl cellulose), 0.5 g of polyvinylidene fluoride (PVDF), 5.5 g of N-methyl-2-pyrrolidinone (NMP) and 0.3 g of water (stock) Mix using a Shinkey Awatori Neritaro ARV-310. After mixing, it is exposed to air atmosphere at 30 ° C and RH 70% for 1 week, and then it is passed through a 250-micron sieve to check whether it is gelled or not, depending on the solid content remaining on the sieve Make a judgment.

<Test method of charge and discharge>
The charge / discharge test was performed at room temperature (25 ° C.) using a lithium ion secondary battery using the lithium excess nickel cobalt manganese composite oxide particles powder produced by the above method as a positive electrode active material.

  For charging, constant current charging was performed at a rate of 0.05 C to a voltage of 4.8 V, and then charging was performed at a constant voltage to a current value of 0.02 C. Discharge was performed at a rate of 0.05 C to a voltage of 2.5 V, and the discharge capacity was measured. At this time, 1 C = 270 mAh / g was defined and carried out.

<Impedance resistance test method>
The resistance value was measured by an alternating current impedance method using a 2032 type coin battery charged with a charging potential of 4.1 V. A frequency response analyzer and a potentiogalvanostat (manufactured by Solartron) were used for the measurement. The obtained Nyquist plot is a characteristic curve showing the negative electrode resistance and the positive electrode resistance in order from the left arc. The positive electrode resistance was a value obtained by extrapolating the second arc into a semicircle.

  Hereinafter, the present invention will be specifically described with reference to examples of the composite oxide powder of the present embodiment and a method for producing the same, but the present invention is not limited to the following examples and the like.

[Evaluation of coated lithium excess nickel cobalt manganese composite oxide]
A coated lithium excess nickel cobalt manganese composite oxide was manufactured as a coated composite oxide particle, and the evaluation was performed.

<Production of coated lithium excess nickel cobalt manganese composite oxide>
[0.5Li ₂ MnO ₃ .0.5LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ]
The nickel-cobalt-manganese composite oxide was heat treated in an air stream at 650 ° C. for 10 hours in an electric furnace to obtain a nickel-cobalt-manganese composite oxide. Thereafter, a nickel-cobalt-manganese composite oxide and lithium carbonate are mixed in a shaker mixer at a ratio of 61.4: 38.6, calcined temporarily at 550 ° C. for 4 hours, and calcined at 950 ° C. for 10 hours. A cobalt-manganese composite oxide was obtained.

[0.5 Li ₂ MnO _3. 0.5 Li [Ni _1/3 Co _1/3 Mn _1/3 ] _0.99 W _0.01 O ₂ ]
The nickel-cobalt-manganese composite oxide was heat treated in an air stream at 650 ° C. for 10 hours in an electric furnace to obtain a nickel-cobalt-manganese composite oxide. Thereafter, the nickel-cobalt-manganese composite oxide, lithium carbonate and tungsten oxide powder are mixed at a ratio of 38.4: 60.8: 0.8 by a shaker mixer and calcined at 550 ° C. for 4 hours, and then 950 ° C. It baked for 10 hours and obtained lithium excess nickel cobalt manganese complex oxide.

Example 1
Lithium excess nickel cobalt manganese complex oxide powder, general formula 0.5Li ₂ MnO ₃ .0.5LiNi _1/3 Co _1/3 Mn _1/3 O ₂ 40 g and CMC 1 wt. Mix. The adhesion amount of CMC (carboxymethylcellulose) was 0.045% by weight. The lithium excess nickel cobalt manganese composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried in an air atmosphere at 150 ° C. in an electric furnace to complete the coating. The lithium excess nickel cobalt manganese composite oxide used at this time had a residual impurity Na grade of 0.57% by weight, and pH = 11.3.

  The charge-discharge test and the gelation test were confirmed for the obtained coated lithium excess nickel cobalt manganese composite oxide powder.

  In the secondary battery charge and discharge test, the discharge capacity was 262 mAh / g, and the sufficient capacity was obtained without the influence of the coating. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained without gelation and without any decrease in charge and discharge capacity.

  As a result of TEM observation of the coated state of the particle surface of the obtained active material, as shown in FIG. 1, the coating of CMC (carboxymethyl cellulose) was confirmed on the particle surface.

(Example 2)
The lithium excess nickel cobalt manganese complex oxide powder was changed to the general formula 0.5Li ₂ MnO ₃ .0.5Li [Ni _1/3 Co _1/3 Mn _1/3 ] _0.99 W _0.01 O ₂ As a result of obtaining and evaluating a positive electrode active material for a non-aqueous electrolyte secondary battery in the same manner as in Example 1, a discharge capacity of 270 mAh / g was obtained, and a sufficient capacity was obtained without the influence of the coating. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation.

(Example 3)
A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that the adhesion amount of CMC (carboxymethylcellulose) was mixed to be 0.86% by weight, and as a result, discharge was obtained. The capacity of 258 mAh / g was not affected by the coating, and a sufficient capacity was obtained. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation.

(Example 4)
A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that the adhesion amount of CMC (carboxymethyl cellulose) was mixed so as to be 0.01% by weight. The capacity was 263 mAh / g and there was no influence of the coating, and a sufficient capacity was obtained. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation.

(Example 5)
In the same manner as in Example 1 except that the drying temperature was changed from 150 ° C. to 250 ° C., a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated. And a sufficient capacity was obtained. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation.

(Example 6)
The positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated in the same manner as in Example 1 except that the drying atmosphere was changed from air to vacuum. As a result, the discharge capacity was 261 mAh / g and the coating had no influence. Sufficient capacity was obtained. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation.

(Example 7)
The positive electrode active material for a non-aqueous electrolyte secondary battery in the same manner as in Example 1 except that the lithium excess nickel cobalt manganese composite oxide has a residual impurity Na grade changed to 0.24 wt% and pH = 11.0. As a result of performing evaluation while obtaining, it was not affected by the discharge capacity 262 mAh / g and the coating, and a sufficient capacity was obtained. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation.

(Example 8)
The positive electrode active material for a non-aqueous electrolyte secondary battery in the same manner as in Example 1 except that the lithium excess nickel cobalt manganese composite oxide has a residual impurity Na grade changed to 0.88% by weight and pH = 11.5. As a result of performing evaluation while obtaining the above, a discharge capacity of 258 mAh / g was not affected by the coating, and a sufficient capacity was obtained. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation.

(Comparative example 1)
A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated in the same manner as in Example 1 except that the adhesion amount of CMC (carboxymethylcellulose) was changed to 0% by weight. As a result, the discharge capacity was 263 mAh / g and Sufficient capacity was obtained. However, in the gelation test, passing through a 250 micron sieve resulted in residual solids remaining on the sieve.

(Comparative example 2)
A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that the adhesion amount of CMC (carboxymethylcellulose) was mixed so as to be 0.0025% by weight. With the capacity of 260 mAh / g, there was no influence of the coating and a sufficient capacity was obtained. However, in the gelation test, passing through a 250 micron sieve resulted in residual solids remaining on the sieve.

(Comparative example 3)
A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that the adhesion amount of CMC (carboxymethylcellulose) was mixed to be 1.5% by weight. The capacity was 233 mAh / g and the effect of the coating was a very low capacity value. However, in the gelation test, no residue was left even after passing through a 250 micron sieve without gelation.

  The lithium excess nickel cobalt manganese composite oxide particles used in Examples and Comparative Examples are shown in Table 1, and the production conditions, discharge capacity and gelation test results of the coated composite oxide particles of Examples and Comparative Examples (in the table, gelation Is shown in Table 2. In addition, the case where it did not gel in gelation test result (it describes with gelatinization in a table | surface) was set as "OK", and the case where it gelatinized was set as "NG."

(Evaluation)
The lithium-rich nickel-cobalt-manganese composite oxides of Examples 1 to 8 are all coated with CMC (carboxymethyl cellulose), and therefore, the elution suppression of the high alkali which they possess is achieved, and thereby gelation The coin-type battery using these positive electrode active materials for non-aqueous electrolyte secondary batteries is a battery having a high initial discharge capacity due to the prevention of and the control of the coating amount.

  Comparative Examples 1 and 2 did not coat or had too little coverage, resulting in gelation. It is considered that this is because the alkali elution of the lithium excess nickel cobalt manganese composite oxide was not suppressed.

In Comparative Example 3, when the coating amount was increased too much, it became a resistance to the insertion and removal of Li ions, and the resistance of the particle interface was also high in addition to the bulk originally high in resistance, resulting in a rapid loss of discharge capacity. .

[Evaluation of coated lithium nickel composite oxide]
The coated lithium nickel composite oxide was manufactured as a coated composite oxide particle, and the evaluation was performed.

<Production of coated lithium nickel composite oxide>
The following evaluation was performed about Examples 9-17 and Comparative Examples 4-11 about lithium nickel complex oxide manufactured by the said manufacturing method. In the impedance resistance test of Examples 9 to 17 and Comparative Examples 4 to 10, the impedance resistance is equal to or less than the impedance resistance of Comparative Example 11, and the impedance resistance is lower than that of Comparative Example 11. It is high.

[Li _1.03 Ni _0.85 Co _0.14 Al _0.01 ]
93 g of nickel cobalt hydroxide was coated with 0.8 g of aluminum hydroxide and heat treated in an air stream at 650 ° C. for 10 hours in an electric furnace to obtain a composite oxide. Thereafter, the complex oxide and lithium hydroxide are mixed in a shaker mixer at a ratio of 36.3: 63.7, and after temporary firing at 550 ° C. for 4 hours, firing is performed at 750 ° C. for 10 hours, lithium nickel cobalt aluminum A composite oxide was obtained.

(Example 9)
The lithium-nickel composite oxide powder is mixed with 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 2 g of a 1% solution of CMC in a dry Naritaro. The adhesion amount of CMC (carboxymethylcellulose) was 0.05% by weight. The lithium nickel composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried at 100 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. The charge / discharge test, the impedance resistance test, and the gelation test were confirmed for the obtained coated lithium nickel composite oxide powder.

  In the secondary battery charge and discharge test, compared to Comparative Example 11 in which the charge capacity is 215 mAh / g and the discharge capacity is 195 mAh / g and the CMC (Carboxymethyl cellulose) is not coated, there is no influence of coating and sufficient charge and discharge capacity is obtained. It is done. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained without gelation and without any decrease in charge and discharge capacity.

(Example 10)
The lithium-nickel composite oxide powder is mixed with 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 2 g of a 1% solution of CMC in a dry Naritaro. The adhesion amount of CMC (carboxymethylcellulose) was 0.05% by weight. The lithium nickel composite oxide powder mixed with CMC was dried at 200 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. The charge / discharge test and the gelation test were confirmed for the coated lithium nickel composite oxide powder.

  In the secondary battery charge / discharge test, the charge capacity of 215 mAh / g, the discharge capacity of 195 mAh / g and the comparative example 11 in which the CMC is not coated are not affected by the coating, and a sufficient charge / discharge capacity is obtained. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained without gelation and without any decrease in charge and discharge capacity.

(Example 11)
The lithium-nickel composite oxide powder is mixed with 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 2 g of a 1% solution of CMC in a dry Naritaro. The adhesion amount of CMC was 0.05% by weight. The lithium nickel composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried at 300 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge and discharge test, compared with Comparative Example 11 in which the charge capacity is 215 mAh / g and the discharge capacity is 194 mAh / g and the CMC is not coated, there is no influence of the coating and a sufficient charge and discharge capacity is obtained. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained without gelation and without any decrease in charge and discharge capacity.

(Example 12)
The lithium-nickel composite oxide powder is mixed with 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 20 g of a 1% solution of CMC in a swirling neritaro. The adhesion amount of CMC (carboxymethylcellulose) was 0.5% by weight. The lithium nickel composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried at 100 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge and discharge test, there is no influence of the coating and sufficient charge and discharge capacity is obtained even in comparison with Comparative Example 11 in which the charge capacity is 213 mAh / g and the discharge capacity is 193 mAh / g and CMC (carboxymethylcellulose) is not coated. It is done. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained without gelation and without any decrease in charge and discharge capacity.

(Example 13)
The lithium-nickel composite oxide powder is mixed with 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 20 g of a 1% solution of CMC in a swirling neritaro. The adhesion amount of CMC (carboxymethylcellulose) was 0.5% by weight. The lithium nickel composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried at 200 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, the charge capacity 212 mAh / g, the discharge capacity 192 mAh / g, and a sufficient charge / discharge capacity are obtained without the influence of the coating as compared with Comparative Example 11 in which the CMC is not coated. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained without gelation and without any decrease in charge and discharge capacity.

(Example 14)
The lithium-nickel composite oxide powder is mixed with 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 20 g of a 1% solution of CMC in a swirling neritaro. The adhesion amount of CMC (carboxymethylcellulose) was 0.5% by weight. The lithium nickel composite oxide powder mixed with CMC was dried at 300 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge and discharge test, the sufficient charge and discharge capacity is obtained without the influence of the coating even in comparison with Comparative Example 11 in which the charge capacity is 211 mAh / g and the discharge capacity is 191 mAh / g and CMC (carboxymethylcellulose) is not coated. It is done. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained without gelation and without any decrease in charge and discharge capacity.

(Example 15)
The lithium-nickel composite oxide powder was mixed with 40 g of a general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 40 g of a 1% solution of CMC in a dry Naritaro. The adhesion amount of CMC was 1.0% by weight. The lithium nickel composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried at 100 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge and discharge test, there is no influence of the coating and sufficient charge and discharge capacity is obtained even in comparison with Comparative Example 11 in which the charge capacity is 210 mAh / g and the discharge capacity is 191 mAh / g and CMC (carboxymethylcellulose) is not coated. It is done. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained without gelation and without any decrease in charge and discharge capacity.

(Example 16)
The lithium-nickel composite oxide powder was mixed with 40 g of a general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 40 g of a 1% solution of CMC in a dry Naritaro. The adhesion amount of CMC (carboxymethylcellulose) was 1.0% by weight. The lithium nickel composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried at 200 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge and discharge test, a sufficient charge and discharge capacity is obtained without the influence of the coating even in comparison with Comparative Example 11 in which the charge capacity is 208 mAh / g and the discharge capacity is 190 mAh / g and the CMC is not coated. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained without gelation and without any decrease in charge and discharge capacity.

(Example 17)
The lithium-nickel composite oxide powder was mixed with 40 g of a general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 40 g of a 1% solution of CMC in a dry Naritaro. The adhesion amount of CMC (carboxymethylcellulose) was 1.0% by weight. The lithium nickel composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried at 300 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, a sufficient charge / discharge capacity is obtained without the influence of the coating even in comparison with Comparative Example 11 in which the charge capacity is 205 mAh / g and the discharge capacity is 188 mAh / g and the CMC is not coated. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained without gelation and without any decrease in charge and discharge capacity.

(Comparative example 4)
A lithium nickel composite oxide powder was prepared by mixing 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 0.1 g of a 1% solution of CMC in a wet Neritaro. The adhesion amount of CMC (carboxymethylcellulose) was 0.0025% by weight. The lithium nickel composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried at 100 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge and discharge test, compared to Comparative Example 11 in which the charge capacity is 215 mAh / g and the discharge capacity is 195 mAh / g and the CMC (Carboxymethyl cellulose) is not coated, there is no influence of coating and sufficient charge and discharge capacity is obtained. It is done. Also, the impedance resistance is low and there is no problem. However, in the gelation test, passing through a 250 micron sieve resulted in residual solids remaining on the sieve. As described above, gelation occurred, and an undesirable positive electrode active material for a non-aqueous electrolyte secondary battery was obtained.

(Comparative example 5)
A lithium nickel composite oxide powder was prepared by mixing 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 0.1 g of a 1% solution of CMC in a wet Neritaro. The adhesion amount of CMC (carboxymethylcellulose) was 0.0025% by weight. The lithium nickel composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried at 200 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, the charge capacity of 215 mAh / g, the discharge capacity of 195 mAh / g and the comparative example 11 in which the CMC is not coated are not affected by the coating, and a sufficient charge / discharge capacity is obtained. Also, the impedance resistance is low and there is no problem. However, in the gelation test, passing through a 250 micron sieve resulted in residual solids remaining on the sieve. As described above, gelation occurred, and an undesirable positive electrode active material for a non-aqueous electrolyte secondary battery was obtained.

(Comparative example 6)
A lithium nickel composite oxide powder was prepared by mixing 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 0.1 g of a 1% solution of CMC in a wet Neritaro. The adhesion amount of CMC was 0.0025% by weight. The lithium nickel composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried at 300 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, the charge capacity of 215 mAh / g, the discharge capacity of 195 mAh / g and the comparative example 11 in which the CMC is not coated are not affected by the coating, and a sufficient charge / discharge capacity is obtained. Also, the impedance resistance is low and there is no problem. However, in the gelation test, passing through a 250 micron sieve resulted in residual solids remaining on the sieve. As described above, gelation occurred, and an undesirable positive electrode active material for a non-aqueous electrolyte secondary battery was obtained.

(Comparative example 7)
The lithium nickel composite oxide powder was mixed with 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 60 g of a 1% solution of CMC in a dry Naritaro. The adhesion amount of CMC (carboxymethylcellulose) was 1.5% by weight. The lithium nickel composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried at 100 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, the charge / discharge capacity is significantly reduced as compared with Comparative Example 11 in which the charge capacity is 195 mAh / g and the discharge capacity is 180 mAh / g and the CMC (carboxymethylcellulose) is not coated. In addition, impedance resistance is also high and there is a problem. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, although the gelation did not occur, the charge / discharge capacity decreased and the impedance resistance increased, so that an undesirable positive electrode active material for a non-aqueous electrolyte secondary battery was obtained.

(Comparative example 8)
The lithium nickel composite oxide powder was mixed with 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 60 g of a 1% solution of CMC in a dry Naritaro. The adhesion amount of CMC (carboxymethylcellulose) was 1.5% by weight. The lithium nickel composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried at 200 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, the charge / discharge capacity is significantly reduced as compared with Comparative Example 11 in which the charge capacity is 195 mAh / g and the discharge capacity is 180 mAh / g and the CMC (carboxymethylcellulose) is not coated. In addition, impedance resistance is also high and there is a problem. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, although the gelation did not occur, the charge / discharge capacity decreased and the impedance resistance increased, so that an undesirable positive electrode active material for a non-aqueous electrolyte secondary battery was obtained.

(Comparative example 9)
The lithium nickel composite oxide powder was mixed with 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 60 g of a 1% solution of CMC in a dry Naritaro. The adhesion amount of CMC (carboxymethylcellulose) was 1.5% by weight. The lithium nickel composite oxide powder mixed with CMC was dried at 300 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, the charge / discharge capacity is significantly reduced as compared with Comparative Example 11 in which the charge capacity is 195 mAh / g and the discharge capacity is 180 mAh / g and the CMC (carboxymethylcellulose) is not coated. In addition, impedance resistance is also high and there is a problem. In the gelation test, no residue was left even after passing through a 250 micron sieve without gelation. As described above, although the gelation did not occur, the charge / discharge capacity decreased and the impedance resistance increased, so that an undesirable positive electrode active material for a non-aqueous electrolyte secondary battery was obtained.

(Comparative example 10)
The lithium-nickel composite oxide powder was mixed with 40 g of the general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 20 g of a 1% solution of CMC in a dry Naritaro. The adhesion amount of CMC (carboxymethylcellulose) was 0.5% by weight. The lithium nickel composite oxide powder mixed with CMC was dried at normal temperature to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charge / discharge test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, the charge capacity of 215 mAh / g, the discharge capacity of 195 mAh / g and the comparative example 11 in which the CMC is not coated are not affected by the coating, and a sufficient charge / discharge capacity is obtained. However, the impedance resistance is also high and there is a problem. In the gelation test, passing through a 250 micron sieve resulted in residual solids remaining on the sieve. As described above, although the charge and discharge capacity was obtained, the impedance resistance increased and gelation occurred, and an undesirable positive electrode active material for a non-aqueous electrolyte secondary battery was obtained.

(Comparative example 11)
Lithium battery and discharge test and gelation test were confirmed for lithium nickel composite oxide powder in which lithium nickel composite oxide powder is not coated with 40 g CMC of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 did.

  In the secondary battery charge and discharge test, a sufficient charge and discharge capacity is obtained even when compared with the charge capacity of 213 mAh / g and the discharge capacity of 193 mAh / g and Examples 9 to 17. Also, the impedance resistance is low and there is no problem. However, in the gelation test, passing through a 250 micron sieve resulted in residual solids remaining on the sieve. As described above, although the charge and discharge capacity was obtained, it was gelled, and an undesirable positive electrode active material for a non-aqueous electrolyte secondary battery was obtained.

  Production conditions, charge capacity, discharge capacity, impedance resistance (expressed as resistance in the table) and gelation test results (expressed as gelation in the table) of the coated composite oxide particles of Examples and Comparative Examples. It is shown in Table 3. In addition, when impedance resistance (it is described as resistance in a table) is low and there is no problem "OK", when impedance resistance increases, it is considered as "NG" and a gelation test result (in the table, it is described as gelation) The case where gelation did not occur in the above was "OK", and the case where gelation was made was "NG".

  From the above results, if the coated composite oxide particles for a positive electrode active material for a non-aqueous electrolyte secondary battery are produced using the production method of the present embodiment, a secondary battery using this positive electrode active material is an initial stage It is preferable because gelation can be prevented without decreasing the discharge capacity.

  The non-aqueous electrolyte secondary battery of the present invention is suitable as a power source for small portable electronic devices (note-type personal computers, mobile phone terminals, etc.) which are required to have a high capacity at all times. In addition, the non-aqueous electrolyte secondary battery of the present invention has excellent safety, and can be miniaturized and increased in capacity, and thus is suitable as a battery for an electric car.

Claims (6)

A heat treatment step of heating the composite hydroxide particles to obtain heat treated particles;
A firing step of obtaining composite oxide particles by mixing the heat-treated particles with lithium and / or a lithium compound and firing the mixture;
The composite oxide particles and the carboxymethyl cellulose solution are mixed to make the attached amount of carboxymethyl cellulose of the composite oxide particles be 0.005% by weight or more and 1.0% by weight or less, under a non-reducing gas atmosphere or under a vacuum atmosphere And a coating step of obtaining coated composite oxide particles by leaving at 100 ° C. or more and 200 ° C. or less, and a method of producing coated composite oxide particles of a positive electrode active material for a non-aqueous electrolyte secondary battery. The composite hydroxide particles are nickel cobalt manganese composite hydroxide particles,
The method for producing coated composite oxide particles according to claim 1, wherein the composite oxide particles are lithium-rich nickel cobalt manganese composite oxide particles represented by the following general formula (1).
bLi ₂ MnO ₃ · (1-b) Li _{1 + u} Ni _x Co _y Mn _z M _t O ₂ (1)
(Wherein, 0.2 ≦ b ≦ 0.8, −0.05 ≦ u ≦ 0.20, x + y + z + t = 1, 0.1 ≦ x ≦ 0.4, 0.2 ≦ y ≦ 0.8, 0 1 ≦ z ≦ 0.4, 0 ≦ t ≦ 0.1, M is an additive element, and at least one selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, W The above elements.) Wherein a composite hydroxide particles crab nickel composite hydroxide particles,
The method for producing coated composite oxide particles according to claim 1, wherein the composite oxide particles are lithium-nickel composite oxide particles represented by the following general formula (2).
Lix Ni _1-y-z Co _{y M z} O ₂ (2)
(Wherein, 0.85 ≦ x ≦ 1.25, 0 <y ≦ 0.5, 0 ≦ z ≦ 0.5, 0 <y + z ≦ 0.75, and the element Me is Al, Mg, Nb, Mn And at least one element selected from the group consisting of Ti and Ca) The concentration of Na contained in the composite hydroxide particles is 0.2% by weight or more and 1.0% by weight or less,
The method for producing coated composite oxide particles according to any one of claims 1 to 3, wherein the pH of the slurry mixed at a ratio of 5 g of the composite hydroxide particles to 100 ml of water is 11.0 or more at 25 ° C.   The method for producing coated complex oxide particles according to any one of claims 1 to 4, wherein the heat treatment step is performed at 500 ° C to 750 ° C. By a method according to any one of claims 1 to 5 to produce a coated composite oxide particles, a method of manufacturing a non-aqueous electrolyte secondary battery using the coated complex oxide particles.