JP2016072188A - Method for manufacturing coated complex oxide particles for positive electrode active material for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery arranged by use of coated complex oxide particles manufactured thereby - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing appropriate complex oxide particles for a positive electrode active material even in the case of using a positive electrode active material of a lithium ion secondary battery, which is easy to cause gelation.SOLUTION: A method for manufacturing coated complex oxide particles comprises: a thermal treatment step where particles subjected to a thermal treatment are obtained; a sintering step where complex oxide particles are obtained; and additionally, coating the particles with CMC(carboxymethylcellulose) into the coated complex oxide particles. The method makes possible to prevent gelation of paste which is a mixture of a positive electrode active material, a binding agent and a conductive material, and to have a good battery property.SELECTED DRAWING: Figure 1

Description

  The present invention relates to 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 a positive electrode active material is used as a positive electrode material. It relates to a method to prevent.

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

  As a secondary battery satisfying such requirements, there is a lithium ion secondary battery. A lithium ion secondary battery includes 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.

  Research and development of lithium ion secondary batteries are currently being actively conducted. Among them, lithium ion secondary batteries using layered or spinel type lithium metal composite oxides as positive electrode materials are 4V class. As a battery having a high energy density is being put into practical use, a high voltage can be obtained.

As an active material for a positive electrode of a lithium ion secondary battery, a lithium cobalt composite oxide (LiCoO ₂ ) that is currently relatively easy to synthesize, a lithium nickel composite oxide (LiNiO ₂ ) using nickel that is cheaper than cobalt, Lithium nickel cobalt manganese composite oxide (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ), lithium manganese composite oxide (LiMn ₂ O ₄ ) using manganese, lithium nickel manganese composite oxide (LiNi _{0. 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-excess nickel cobalt manganese composite oxide (Li ₂ MnO ₃ —LiNi _x Mn _y Co _z O ₂ ) has attracted attention from the viewpoint of high capacity and excellent thermal stability. The lithium-excess nickel cobalt manganese composite oxide is a layered compound like the lithium cobalt composite oxide and the lithium nickel composite oxide (see Non-Patent Document 1).

Further, lithium nickel composite oxide (LiNiO ₂ ) using nickel, which is cheaper than cobalt, has attracted attention from the viewpoint of higher discharge capacity, lower cost of raw materials, and stable supply.

  However, the gelation of the paste which is a mixture of these positive electrode active materials, the binder and the conductive material becomes a problem. The gelation of the paste refers to a state in which the fluidity and uniformity are lost due to an increase in viscosity, and when the gelation is extremely advanced, coating on the current collector becomes impossible. Also, even if it is mildly gelled, it is greatly involved in the resistance value of the prepared electrode sheet, and the battery characteristics such as discharge capacity, current density dependency, and low temperature characteristics are deteriorated. Prevention of gelation has been a serious problem to be solved in electrode preparation.

  Therefore, a measure for preventing gelation of the active material of the positive electrode of the lithium ion secondary battery is an important issue.

  In this regard, Patent Document 1 includes an electrode mixture (positive electrode paste) to which an acid is added in addition to a powder electrode material such as a binder (binder) made of a vinylidene fluoride polymer and positive electrode active material particles. ing. However, in the electrode mixture (positive electrode paste) of Patent Document 1, when applied and dried as a positive electrode active material layer in a battery after application, the added acid-derived anions are contained in the battery electrolyte. There was a problem of elution and deterioration of battery characteristics.

  Patent Document 2 discloses an active material in which a zirconia sol solution is sprayed on a powder such as lithium cobaltate to cover the entire surface of 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 over the entire surface, the lithium ion diffusion rate decreases, so that insertion / extraction of lithium ions becomes difficult and movement of lithium ions becomes difficult. As a result, 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 active material surface is metal-coated by mixing a LiMnO-based active material into a metal alkoxide solution and then firing the mixture. This is to improve the cycle characteristics by suppressing the reactivity between the active material and the electrolytic solution by the metal coating on the surface of the active material. However, since the metal coating is a part of the active material surface, the deterioration of the active material and the electrolytic solution due to the reaction between the active material and the electrolytic solution is not sufficient, and sufficient cycle characteristics cannot be obtained. It was.

Japanese Patent No. 354080 JP 2006-156032 A JP-A-2005-78800

FB Technical News, No. 66, 2011.1.1

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

  As a result of intensive studies to solve the above-described problems of the prior art, the present inventors have added a step of coating CMC (carboxymethylcellulose) in the method for producing composite oxide particles to obtain coated composite oxide particles. Thus, the present inventors have found that gelation of a paste, which is a mixture of a positive electrode active material for a non-aqueous electrolyte secondary battery, a binder and a conductive material, can be prevented, and the present invention has been completed.

  That is, in the first aspect of the present invention, a composite oxide particle is obtained by heating a composite hydroxide particle to obtain a heat-treated particle, mixing the heat-treated particle and lithium or / and a lithium compound, and firing the mixture. The firing step, the composite oxide particles and 0.005 wt% or more and 1.0 wt% or less of carboxymethyl cellulose solution are mixed, and the temperature is 100 ° C. or more and 300 ° C. or less in a non-reducing gas atmosphere or vacuum atmosphere. And a coating step of obtaining coated composite oxide particles by allowing to stand, and a method for producing coated composite oxide particles for a positive electrode active material for a non-aqueous electrolyte secondary battery.

In the second aspect of the present invention, 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 1st invention which is particles.
bLi ₂ MnO _3. (1-b) Li _{1 + u} Ni _x Co _y Mn _z M _t O ₂ (1)
(Where, 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 0.1 ≦ z ≦ 0.4, 0 ≦ t ≦ 0.1, M is an additive element, and is at least one selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W The above elements.)

According to a third aspect of the present invention, the composite hydroxide particles are lithium nickel composite hydroxide particles, and the composite oxide particles are lithium nickel composite oxide particles represented by the following general formula (2). It is a manufacturing method of the covering complex oxide particles given in one invention.
LixNi _1-yz Co _y Me _z O ₂ (2)
(In the formula, 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 , At least one element selected from the group consisting of Ti and Ca.)

  According to a 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 is mixed at a ratio of 5g of the composite hydroxide particles to 100ml of water. The method for producing coated composite oxide particles according to any one of the first to third inventions, wherein the pH of the prepared slurry is 11.0 or more at 25 ° C.

  A fifth aspect of the present invention is the method for producing coated composite oxide particles according to any one of the first to fourth aspects, wherein the heat treatment step is performed at 500 ° C. or higher and 750 ° C. or lower.

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

  According to the present invention, the positive electrode active material can prevent gelation by forming a CMC (carboxymethylcellulose) coating layer on the surface of the composite oxide. Therefore, a non-aqueous secondary battery composed of a positive electrode containing the positive electrode active material has excellent battery characteristics and a low defective rate, 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 present invention is not limited to the embodiments described below.

<Composite oxide>
The composite oxide powder of the present invention is not particularly limited as long as it can be used as an active material for 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 was used. Lithium manganese composite oxide (LiMn ₂ O ₄ ), lithium nickel manganese composite oxide (LiNi _0.5 Mn _0.5 O ₂ ), lithium-excess nickel cobalt manganese composite oxide (Li ₂ MnO ₃ —LiNi _x Mn _y Co) _z O ₂ ) and the like.

[Lithium-rich nickel cobalt manganese composite oxide]
The lithium-rich 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 one or more elements selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and 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 a non-aqueous electrolyte secondary battery is increased, so that the output of the battery is lowered. . On the other hand, when u exceeds 0.20, the initial discharge capacity when the positive electrode active material is used for the positive electrode of the battery decreases, and the reaction resistance of the positive electrode also increases. Therefore, u is set to be −0.05 or more and 0.20 or less and preferably 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 the non-aqueous electrolyte secondary battery of the present embodiment is adjusted so as to contain an additive element in the lithium-excess nickel cobalt manganese composite oxide particles. More preferably. By including the additive element, it is possible to improve the durability and output characteristics of a battery using the additive element as a positive electrode active material for a non-aqueous electrolyte secondary battery.

  In particular, since the additive element is uniformly distributed on the surface or inside of the particle, the above effect can be obtained with the whole particle, and the above effect can be obtained with a small amount of addition, and a decrease in capacity can be suppressed. Furthermore, in order to obtain the effect with a smaller addition amount, it is preferable to increase the concentration of the additive element on the particle surface from the inside of the particle.

  When the atomic ratio t of the additive element M with respect to all atoms exceeds 0.1, the metal elements contributing to the reduction reaction decrease, which is not preferable because the battery capacity decreases. Therefore, the additive element M is adjusted so that the atomic ratio t is 0 or more and 0.1 or less.

  The average particle size of the active material is preferably in the range of 2.0 μm or more and 8.0 μm or less. When the average particle diameter is less than 2 μm, the packing density of the particles decreases when the positive electrode is formed, and the battery capacity per positive electrode volume decreases. On the other hand, when the average particle size exceeds 8.0 m, the specific surface area of the positive electrode active material for a non-aqueous electrolyte secondary battery decreases and the interface with the battery electrolyte decreases, thereby increasing the resistance of the positive electrode. Battery output characteristics will deteriorate.

  Therefore, if the average particle size is adjusted to 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, the non-aqueous electrolyte 2 is adjusted. A battery using a positive electrode active material for a secondary battery as a positive electrode can increase the battery capacity per volume and obtain battery characteristics excellent in high safety, high output, and the like.

  The structure and composition of the lithium-rich nickel cobalt manganese composite oxide can be identified by X-ray diffraction (XRD), electron diffraction, emission spectroscopic analysis (ICP), and the like. In a high-resolution image using a high-resolution transmission electron microscope (TEM), the layered structure can be observed by finely processing the sample even if the sample is relatively large particles.

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

Li _x Ni _1-yz Co _y Me _z O ₂ (2)
(In the formula, 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 , At least one selected from the group consisting of Ti and Ca.)

  The structure and composition of the lithium nickel composite oxide can be identified by X-ray diffraction (XRD), electron diffraction, emission spectroscopic analysis (ICP), and the like. In a high-resolution image using a high-resolution transmission electron microscope (TEM), the layered structure can be observed by finely processing the sample even if the sample is relatively large particles.

<Method for producing coated composite oxide particles>
The method for producing coated composite oxide particles according to this embodiment includes: a) a heat treatment step in which the composite hydroxide particles are heated to obtain heat treated particles; and b) heat treated particles and lithium or / and a lithium compound are mixed and fired. A firing step for obtaining composite oxide particles, and c) mixing the composite oxide particles with 0.005 wt% or more and 1.0 wt% or less of CMC (carboxymethylcellulose) solution to form a non-reducing gas or vacuum And a coating step of obtaining coated composite oxide particles by leaving them at 100 ° C. or more and 300 ° C. or less in an atmosphere. Hereinafter, each process will be described.

a) Heat treatment step The heat treatment step is a step of heating and heat-treating the composite hydroxide particles, and is a step of removing water contained in the composite hydroxide particles. By performing this heat treatment step, the moisture remaining in the composite hydroxide particles until the firing step can be reduced to a certain amount. Thereby, it can prevent that the ratio of the number of metal atoms and the number of lithium atoms of the obtained coated composite oxide particles varies.

  In the heat treatment step, it is sufficient that moisture can be removed to such an extent that the ratio of the number of metal atoms and the number of lithium atoms in the composite hydroxide particles does not vary. The heating temperature is preferably 100 ° C. or higher and 750 ° C. or lower, and more preferably 500 ° C. or higher and 750 ° C. or lower. When heating temperature is less than 100 degreeC, the excess water | moisture content in a composite hydroxide particle cannot be removed, but there exists a tendency for it to become difficult to suppress the said dispersion | variation. On the other hand, when the heating temperature exceeds 750 ° C., the particles are sintered by heat treatment, and it tends to be difficult to obtain composite oxide particles having a uniform particle size.

  Further, it is more preferable that the heating temperature is 500 ° C. or higher because all of the composite hydroxide particles can be converted into composite oxide particles. 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 ratio with a lithium compound.

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

  Further, the heat treatment time is not particularly limited, but if it is less than 1 hour, the excess water of the composite hydroxide particles may not be sufficiently removed, and therefore, it is preferably at least 1 hour or more and 5 hours or more and 15 hours or less. More preferred.

  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 no electric gas is generated. 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 or / and a lithium compound and firing them.

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

(mixture)
The heat-treated particles and lithium or / and lithium compound are the ratio of the number of atoms of metals other than lithium, that is, the sum of the number of atoms of nickel, cobalt, manganese and additive elements (Me) to the number of atoms of lithium (Li). It is preferable to mix so that (Li / Me) is 1.2 to 1.8, preferably 1.4 to 1.6. 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 a non-aqueous electrolyte secondary battery, and thus Li / Me in the lithium mixture. However, it mixes so that it may become the same as Li / Me in the positive electrode active material for non-aqueous electrolyte secondary batteries 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 because it is easily available. In particular, lithium hydroxide or lithium carbonate is more preferably used in consideration of ease of handling and quality stability. In addition, when the complex oxide particle which is a target object is a lithium nickel complex oxide particle represented by General formula (2), it is preferable to use lithium hydroxide.

  In addition, it is preferable to mix sufficiently before baking. If the mixing is not sufficient, Li / Me varies among individual particles, which may cause problems such as insufficient battery characteristics.

  For mixing, a general mixer can be used. For example, a shaker mixer, a Laedige mixer, a Julia mixer, a V blender, or the like can be used. The substance particles and the substance containing lithium may be mixed sufficiently.

(Baking)
This step is a step of firing the mixture to obtain composite oxide particles. By baking the lithium mixture, lithium contained in the lithium mixture diffuses into the heat-treated particles, and composite oxide particles are generated.

((Baking temperature))
The firing temperature is preferably determined by the target composite oxide particles. For example, when the target composite oxide particles are lithium-rich nickel cobalt manganese composite oxide particles represented by the general formula (1), it is preferably performed at 850 ° C. or higher and 1050 ° C. or lower, and 900 ° C. or higher. More preferably, it is carried out at 1000 ° C. or lower. When the firing temperature is less than 850 ° C., lithium is not sufficiently diffused into the heat-treated particles, so that excess lithium and unreacted particles remain or the crystal structure becomes insufficient, and is used in a battery. In this case, it is difficult to obtain sufficient battery characteristics. When the firing temperature exceeds 1050 ° C., intense sintering occurs between the composite oxide particles and abnormal grain growth may occur. For this reason, the particles after firing become coarse and have a particle form (spherical shape described later). There is a tendency that the secondary particle morphology) cannot be maintained. Since such a coated composite oxide particle has a reduced specific surface area, when used in a battery, there arises a problem that the resistance of the positive electrode increases and the battery capacity decreases.

  Moreover, when the composite oxide particle which is a target object is a lithium nickel composite oxide particle represented by the general formula (2), it is preferably performed at 600 ° C. or higher and 800 ° C. or lower, and 730 ° C. or higher and 760 ° C. or lower. More preferably,

  In addition, from the viewpoint of uniformly performing the reaction between the heat-treated particles and the lithium compound, it is preferable to raise the temperature to the above temperature with a temperature increase rate of 3 ° C./min to 10 ° C./min. Furthermore, the reaction can be performed more uniformly by maintaining at a temperature near the melting point of the lithium compound for about 1 hour to 5 hours.

((Baking time))
The firing time is preferably determined by the target composite oxide particles. For example, when the composite oxide particles are lithium-excess nickel cobalt manganese composite oxide particles represented by the general formula (1), the retention time is preferably at least 2 hours, more preferably 4 More than 24 hours. When it is less than 2 hours, the composite oxide may not be sufficiently generated. When 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, more preferably It is 10 hours or more and 24 hours or less. When the time is less than 1 hour, the composite oxide may not be sufficiently generated.

  After the holding time is finished, there is no particular limitation, but when the mixture is loaded on the mortar and fired, the descent rate is set to 2 ° C./min or more and 10 ° C./min or less in order to suppress deterioration of the mortar. It is preferable to cool the atmosphere until it becomes 200 ° C. or lower.

(Preliminary firing process)
In particular, when lithium hydroxide or lithium carbonate is used as the lithium compound, it is preferable that a preliminary firing step is further included before firing. The calcination temperature in the preliminary calcination step is preferably performed at the reaction temperature of lithium hydroxide or lithium carbonate and the heat-treated particles. That is, the firing temperature in the temporary firing step is preferably 350 ° C. or higher and 800 ° C. or lower, more preferably 450 ° C. or higher and 780 ° C. or lower. The firing time in the temporary firing step is about 1 hour to 10 hours, preferably 3 hours to 6 hours. By maintaining lithium hydroxide or lithium carbonate in the vicinity of the reaction temperature, lithium can be sufficiently diffused into the heat-treated particles, so that more uniform composite oxide particles can be obtained.

  In addition, when it is desired to increase the concentration of the additive element on the surface of the composite oxide particle, the heat-treated particles as the raw material may be those in which the particle surface is uniformly coated with the additive element. By baking the lithium mixture containing the 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, the concentration of the additive element M on the particle surface was increased by firing the lithium mixture containing the composite hydroxide particles coated with the additive element at a low firing temperature and a short firing time. Composite oxide particles can be obtained.

  Even when the lithium mixture containing composite hydroxide particles coated with the additive element is fired, the composite oxide particles in which the additive element is uniformly distributed in the particles when the firing temperature is increased and the firing time is lengthened. Can be obtained. That is, by adjusting the heat-treated particles as raw materials and the firing conditions, oxide particles having a target concentration distribution can be obtained.

((Baking atmosphere))
The atmosphere during firing is preferably an oxidizing atmosphere, more preferably an oxygen concentration of 18% by volume or more and 100% by volume or less, particularly a mixed atmosphere of oxygen and an inert gas having the oxygen concentration. preferable. That is, firing is preferably performed in the air or in an oxygen stream. If the oxygen concentration is less than 18% by volume, the crystallinity of the lithium-excess nickel cobalt manganese composite oxide may be insufficient. Considering battery characteristics in particular, it is preferably performed in an oxygen stream.

  The furnace used for firing is not particularly limited as long as the lithium mixture can be heated in the air or an oxygen stream, but there is no gas generation from the viewpoint of keeping the atmosphere in the furnace uniform. An electric furnace is preferred, and either a batch type or a continuous type furnace can be used.

(Disintegration)
The composite oxide particles obtained by firing may be agglomerated or slightly sintered. In this case, it may be crushed, whereby composite oxide particles can be obtained. Note that pulverization means that mechanical energy is applied to an aggregate composed of a plurality of secondary particles generated by sintering necking between secondary particles during firing, and the secondary particles themselves are hardly destroyed. This is an operation of separating the secondary particles and loosening the aggregates.

c) Coating step In the coating step, the composite oxide particles are mixed with 0.005 wt% or more and 1.0 wt% or less CMC (carboxymethylcellulose) solution, and 100 ° C or higher in a non-reducing gas or vacuum atmosphere. This is a step of obtaining coated composite oxide particles by leaving them at 300 ° C. or lower. The present invention can provide composite oxide particles for a positive electrode active material for a non-aqueous electrolyte secondary battery that are excellent in air stability at an early stage by adding a coating step after the firing step. For this reason, the subsequent steps can be performed in an air atmosphere, and expensive equipment introduction costs and running costs are not required to maintain the manufacturing environment. Therefore, the present invention is a manufacturing method with extremely high productivity.

  The composite oxide particles can be coated with CMC (carboxymethylcellulose) by bringing the composite oxide particles into contact 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 the composite oxide particles and hydrogen bonds. Since the composite oxide particles can be coated by such a simple method, the production method is extremely high in productivity.

  Moreover, the pH of the slurry in which the Na concentration of impurities is 0.2 wt% or more and 1.0 wt% or less and mixed at a ratio of 5 g of active material to 100 ml of pure water is 11.0 or more at 25 ° C. In the case of composite oxide particles for a positive electrode active material for an aqueous electrolyte secondary battery, the effect of the CMC (carboxymethylcellulose) coating of the present invention is very high. This is because the complex oxide particles having a high Na concentration of 0.2% by weight or more show the above pH of 11.0 or more, thereby causing gelation during the production of the positive electrode coating slurry. This is because there is an effect of suppressing elution of Na. Therefore, the present invention is particularly effective when a 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.

(Solvent removal)
In the present embodiment, the solvent in the CMC (carboxymethylcellulose) mixed solution is removed by mixing with a CMC (carboxymethylcellulose) solution and leaving it at 100 ° C. or higher and 300 ° C. or lower in a non-reducing gas or vacuum atmosphere. The non-reducing gas refers to a gas having no reducing properties such as air, oxygen, argon, and nitrogen. The solvent contained in the coated composite oxide particles can be removed by heating and drying at 100 ° C. or higher and 300 ° C. or lower in a non-reducing gas or vacuum atmosphere. By carrying out in 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 higher and 300 ° C. or lower, and preferably 100 ° C. or higher 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, CMC (carboxymethylcellulose) may be decomposed, which is not preferable. The heating time is preferably 1 hour or longer.

<Preparation of secondary battery>
When the positive electrode active material for a non-aqueous electrolyte secondary battery manufactured using the above coated composite hydroxide particles is used for the positive electrode of a 2032 type coin battery, for example, a high initial discharge capacity of 250 mAh / g or more can be obtained. Thus, it exhibits excellent characteristics as a positive electrode active material for a non-aqueous electrolyte secondary battery.

  The nonaqueous electrolyte secondary battery employs a positive electrode using the positive electrode active material for a nonaqueous electrolyte secondary battery as a positive electrode material. First, the structure of the nonaqueous electrolyte secondary battery of this embodiment will be described.

  The non-aqueous electrolyte secondary battery of this embodiment has a structure substantially similar to that of a general non-aqueous electrolyte secondary battery except that the coated composite hydroxide particles are used.

  Specifically, the non-aqueous electrolyte secondary battery of this embodiment has a structure including a case, a positive electrode, a negative electrode, a non-aqueous electrolyte solution, and a separator housed in the case. More specifically, a positive electrode and a negative electrode are laminated via a separator to form an electrode body, and the obtained electrode body is impregnated with a non-aqueous electrolyte, and a positive electrode current collector of the positive electrode and a positive electrode terminal connected to the outside are provided. And the negative electrode current collector of the negative electrode and the negative electrode terminal communicating with the outside using a current collecting lead or the like, and sealed in a case, the non-aqueous electrolyte secondary of this embodiment A battery is formed.

  It should be noted that the structure of the nonaqueous electrolyte secondary battery of the present embodiment is not limited to the above example, and various shapes such as a cylindrical shape and a laminated shape can be adopted as the outer shape.

(Positive electrode)
First, a positive electrode that is a feature of the nonaqueous 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 the positive electrode mixture paste containing the positive electrode active material for the non-aqueous electrolyte secondary battery of the present embodiment, for example, on the surface of a current collector made of aluminum foil Has been.

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

  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 a positive electrode active material for a non-aqueous electrolyte secondary battery of the present embodiment, which is in a powder form, a conductive material, and a binder.

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

  The binder plays a role of tethering the coated composite hydroxide particles. The binder used in this positive electrode mixture is not particularly limited. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), fluorine rubber, ethylene propylene diene rubber, styrene butadiene, cellulose resin, Polyacrylic acid or the like can be used.

  In addition, activated carbon etc. may be added to a positive electrode compound material, and the electric double layer capacity | capacitance of a positive electrode can be increased by adding activated carbon etc.

  The solvent dissolves the binder and disperses the positive electrode active material for the non-aqueous electrolyte secondary battery, the conductive material, activated carbon, and the like in the binder. Although this solvent is not specifically limited, For example, organic solvents, 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 as in the case of the positive electrode of a general non-aqueous electrolyte secondary battery. The content of the conductive material can be 1 part by mass or more and 20 parts by mass or less, and the content of the binder can be 1 part by mass or more and 20 parts by mass or less.

(Negative electrode)
The negative electrode is a sheet-like member formed by applying a negative electrode mixture paste on the surface of a metal foil current collector such as copper and drying it. The negative electrode is formed by substantially the same method as the positive electrode, although the components constituting the negative electrode mixture paste, the composition thereof, and the current collector material are different. Is done.

  The negative electrode mixture paste is a paste obtained by adding an appropriate solvent to a negative electrode mixture in which a negative electrode active material and a binder are mixed.

  As the negative electrode active material, for example, a lithium-containing material such as metallic lithium or a lithium alloy, or an occlusion material that can occlude and desorb lithium ions can be employed.

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

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

(Non-aqueous electrolyte)
The nonaqueous electrolytic solution is obtained by dissolving a lithium salt as a supporting salt in an organic solvent.

  Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate; chain carbonates such as diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate, and dipropyl carbonate; Ether compounds such as methyltetrahydrofuran and dimethoxyethane; sulfur compounds such as ethyl methyl sulfone and butane sultone; phosphorus compounds such as triethyl phosphate and trioctyl phosphate alone, or a mixture 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. In addition, the non-aqueous electrolyte solution may contain a radical scavenger, a surfactant, a flame retardant and the like for improving battery characteristics.

(Characteristics of the non-aqueous electrolyte secondary battery of this embodiment)
The non-aqueous electrolyte secondary battery of the present embodiment has the above-described configuration and has a positive electrode using the coated composite oxide particles of the present embodiment. Therefore, a high initial discharge capacity, a low positive electrode resistance are obtained, and a high High output with capacity. In particular, the lithium-excess nickel cobalt manganese composite oxide has high thermal stability and excellent safety compared to other positive electrode active materials for non-aqueous electrolyte secondary batteries of lithium nickel oxides. I can say that.

(Use of secondary battery of this embodiment)
Since the non-aqueous electrolyte secondary battery of the present embodiment has the above properties, it is suitable for a power source of a small portable electronic device such as a notebook personal computer or a mobile phone terminal that always requires a high capacity.

  Further, the secondary battery of the present embodiment is also suitable for a battery as a motor driving power source required for an electric vehicle. When a battery becomes large, it becomes difficult to ensure safety, and an expensive protection circuit is indispensable. However, the nonaqueous electrolyte secondary battery of this embodiment has excellent safety, so In addition to facilitating ensuring the performance, an expensive protection circuit can be simplified and the cost can be further reduced. And since it can be reduced in size and increased in output, it is suitable as a power source for transportation equipment subject to restrictions on the mounting space.

<Geling test method>
9.5 g of coated composite oxide powder coated with CMC (carboxymethylcellulose), 0.5 g of polyvinylidene fluoride (PVDF), 5.5 g of N-methyl-2-pyrrolidinone (NMP) and 0.3 g of water Mix using Awatori Nertaro ARV-310 manufactured by Shinky Corporation. One week after mixing, it was exposed to an air atmosphere of 30 ° C. and RH 70%, and then checked to see if it was gelled. Make a decision.

<Charging / discharging test method>
A 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 powder produced by the above method as a positive electrode active material.

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

<Impedance resistance test method>
Using a 2032 type coin battery charged at a charging potential of 4.1 V, the resistance value was measured by the AC impedance method. For the measurement, a frequency response analyzer and a potentiogalvanostat (manufactured by Solartron) were used. The obtained Nyquist plot is a characteristic curve showing the negative resistance and the positive resistance in order from the left arc. The positive electrode resistance was a value obtained by extrapolating the second arc so as to be a semicircle.

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

[Evaluation of coated lithium-rich nickel cobalt manganese composite oxide]
A coated lithium-excess nickel cobalt manganese composite oxide was produced as the coated composite oxide particles and evaluated.

<Production of coated lithium-rich 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 hydroxide 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, nickel cobalt manganese composite oxide and lithium carbonate were mixed at a ratio of 61.4: 38.6 by a shaker mixer, pre-baked at 550 ° C. for 4 hours, then baked at 950 ° C. for 10 hours, and lithium-excess nickel A cobalt manganese composite oxide was obtained.

[0.5Li ₂ MnO ₃ .0.5Li [Ni _1/3 Co _1/3 Mn _1/3 ] _0.99 W _0.01 O ₂ ]
The nickel cobalt manganese composite hydroxide 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, nickel cobalt manganese composite oxide, lithium carbonate, and tungsten oxide powder were mixed at a ratio of 38.4: 60.8: 0.8 with a shaker mixer, and calcined at 550 ° C. for 4 hours, and then 950 ° C. Firing was performed for 10 hours to obtain a lithium-excess nickel cobalt manganese composite oxide.

Example 1
Lithium-excess nickel cobalt manganese composite oxide powder is a 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% solution 2 g Mix. The amount of CMC (carboxymethylcellulose) deposited was 0.045% by weight. Lithium-excess nickel cobalt manganese composite oxide powder mixed with CMC (carboxymethyl cellulose) was dried in an electric furnace at 150 ° C. in an air atmosphere to complete the coating. The lithium-excess nickel-cobalt-manganese composite oxide used at this time had a residual impurity Na quality of 0.57 wt% and pH = 11.3.

  About the obtained covering lithium excess nickel cobalt manganese complex oxide powder, the charging / discharging test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, the discharge capacity was 262 mAh / g, which was not affected by the coating, and a sufficient capacity was obtained. In the gelation test, no residue remained 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 that did not gel and did not decrease the charge / discharge capacity was obtained.

  As a result of TEM observation of the coating state of the obtained active material on the particle surface, it was confirmed that the particle surface was coated with CMC (carboxymethylcellulose) as shown in FIG.

(Example 2)
Except for changing the lithium-excess nickel cobalt manganese composite oxide powder 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 In the same manner as in Example 1, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated. As a result, a discharge capacity of 270 mAh / g and a sufficient capacity were obtained without being affected by the coating. In the gelation test, no residue remained even after passing through a 250 micron sieve without gelation.

(Example 3)
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 except that the amount of CMC (carboxymethylcellulose) adhered was 0.86% by weight. A capacity of 258 mAh / g was not affected by the coating, and a sufficient capacity was obtained. In the gelation test, no residue remained even after passing through a 250 micron sieve without gelation.

Example 4
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 except that the amount of CMC (carboxymethylcellulose) adhering was mixed so as to be 0.01% by weight. A capacity of 263 mAh / g was not affected by the coating, and a sufficient capacity was obtained. In the gelation test, no residue remained even after passing through a 250 micron sieve without gelation.

(Example 5)
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 except that the drying temperature was changed from 150 ° C. to 250 ° C., the discharge capacity was 260 mAh / g and the influence of the coating. Not enough capacity was obtained. In the gelation test, no residue remained even after passing through a 250 micron sieve without gelation.

(Example 6)
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 except that the drying atmosphere was changed from air to vacuum, the discharge capacity was 261 mAh / g and the coating was not affected. Sufficient capacity was obtained. In the gelation test, no residue remained even after passing through a 250 micron sieve without gelation.

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

(Example 8)
The lithium-excess nickel cobalt manganese composite oxide was the same as in Example 1 except that the remaining impurity Na quality was changed to 0.88 wt% and pH = 11.5. As a result of evaluation, the discharge capacity was 258 mAh / g, which was not affected by the coating, and a sufficient capacity was obtained. In the gelation test, no residue remained even after passing through a 250 micron sieve without gelation.

(Comparative Example 1)
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 except that the amount of CMC (carboxymethylcellulose) attached was 0% by weight, the discharge capacity was 263 mAh / g. Sufficient capacity was obtained. However, in the gelation test, the result was that residual solids remained on the sieve by passing through a 250-micron sieve.

(Comparative Example 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, except that the amount of CMC (carboxymethylcellulose) adhering was 0.0025% by weight. A capacity of 260 mAh / g was not affected by the coating, and a sufficient capacity was obtained. However, in the gelation test, the result was that residual solids remained on the sieve by passing through a 250-micron sieve.

(Comparative Example 3)
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 except that the amount of CMC (carboxymethylcellulose) adhering to 1.5% by weight was mixed. The capacity was 233 mAh / g, which was considerably low due to the influence of the coating. However, in the gelation test, no residue remained even after passing through a 250-micron sieve without gelation.

  The lithium-excess nickel cobalt manganese composite oxide particles used in the 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 the examples and comparative examples (in the table, gelation) Are shown in Table 2. In the gelation test results (indicated as gelation in the table), the case where gelation did not occur was designated as “OK”, and the case where gelation occurred was designated as “NG”.

(Evaluation)
The lithium-excess nickel cobalt manganese composite oxides of Examples 1 to 8 are all coated with CMC (carboxymethylcellulose), and therefore, the high alkali elution suppression is performed, thereby gelling. The coin-type battery using the positive electrode active material for a non-aqueous electrolyte secondary battery is a battery having a high initial discharge capacity by preventing the above and controlling the coating amount.

  Since Comparative Examples 1 and 2 were not coated or the coating amount was too small, gelation was caused. This is considered that the alkali elution of lithium excess nickel cobalt manganese complex oxide was not suppressed.

In Comparative Example 3, an excessive increase in the coating amount resulted in resistance to de-insertion of Li ions, and the resistance at the particle interface increased in addition to the originally high resistance bulk, resulting in a rapid loss of discharge capacity. .

[Evaluation of coated lithium nickel composite oxide]
Coated lithium-nickel composite oxide was produced as the coated composite oxide particles and evaluated.

<Manufacture of coated lithium nickel composite oxide>
About Examples 9-17 and Comparative Examples 4-11, the following evaluation was performed about the lithium nickel composite oxide manufactured by the said manufacturing method. In the impedance resistance tests of Examples 9 to 17 and Comparative Examples 4 to 10, it is assumed that the impedance resistance is equal to or lower than that of Comparative Example 11 and that the impedance resistance is higher than that of Comparative Example 11. High.

[Li _1.03 Ni _0.85 Co _0.14 Al _0.01 ]
A composite oxide was obtained by coating 93 g of nickel cobalt hydroxide with 0.8 g of aluminum hydroxide and performing heat treatment in an air flow at 650 ° C. for 10 hours in an electric furnace. Thereafter, the composite oxide and lithium hydroxide were mixed at a ratio of 36.3: 63.7 with a shaker mixer, calcined at 550 ° C. for 4 hours, and then calcined at 750 ° C. for 10 hours. A composite oxide was obtained.

Example 9
Lithium nickel composite oxide powder is mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 2 g of CMC 1% solution by Nawataro. The amount of CMC (carboxymethylcellulose) deposited was 0.05% by weight. Lithium nickel composite oxide powder mixed with CMC (carboxymethylcellulose) was dried at 100 ° C. in an electric furnace filled with an oxygen atmosphere to complete the coating. About the obtained covering lithium nickel complex oxide powder, the charging / discharging test, the impedance resistance test, and the gelation test were confirmed.

  The charge / discharge test of the secondary battery has a charge capacity of 215 mAh / g, a discharge capacity of 195 mAh / g, and a sufficient charge / discharge capacity with no influence of coating even when compared with Comparative Example 11 which does not cover CMC (carboxymethylcellulose). It has been. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue remained 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 that did not gel and did not decrease the charge / discharge capacity was obtained.

(Example 10)
Lithium nickel composite oxide powder is mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 2 g of CMC 1% solution by Nawataro. The amount of CMC (carboxymethylcellulose) deposited 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, even when compared with Comparative Example 11 in which the charge capacity is 215 mAh / g, the discharge capacity is 195 mAh / g and the CMC is not coated, there is no influence of 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 remained 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 that did not gel and did not decrease the charge / discharge capacity was obtained.

(Example 11)
Lithium nickel composite oxide powder is mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 2 g of CMC 1% solution by Nawataro. The amount of CMC deposited was 0.05% by weight. Lithium nickel composite oxide powder mixed with CMC (carboxymethylcellulose) 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 charging / discharging test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, the charge capacity is 215 mAh / g, the discharge capacity is 194 mAh / g, and even if compared with Comparative Example 11 in which CMC is not coated, there is no influence of 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 remained 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 that did not gel and did not decrease the charge / discharge capacity was obtained.

(Example 12)
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% CMC solution with Niwataro Awatori. The amount of CMC (carboxymethylcellulose) deposited was 0.5% by weight. Lithium nickel composite oxide powder mixed with CMC (carboxymethylcellulose) 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 charging / discharging test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, there was no influence of coating even when compared with Comparative Example 11 in which the charge capacity was 213 mAh / g, the discharge capacity was 193 mAh / g, and CMC (carboxymethylcellulose) was not coated, and sufficient charge / discharge capacity was obtained. It has been. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue remained 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 that did not gel and did not decrease the charge / discharge capacity was obtained.

(Example 13)
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% CMC solution with Niwataro Awatori. The amount of CMC (carboxymethylcellulose) deposited was 0.5% by weight. Lithium nickel composite oxide powder mixed with CMC (carboxymethylcellulose) 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 charging / discharging test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, even when compared with Comparative Example 11 in which the charge capacity is 212 mAh / g, the discharge capacity is 192 mAh / g and the CMC is not coated, there is no influence of 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 remained 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 that did not gel and did not decrease the charge / discharge capacity was obtained.

(Example 14)
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% CMC solution with Niwataro Awatori. The amount of CMC (carboxymethylcellulose) deposited 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 charging / discharging test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, the charge capacity was 211 mAh / g, the discharge capacity was 191 mAh / g, and even when compared with Comparative Example 11 in which CMC (carboxymethylcellulose) was not coated, there was no influence of coating, and sufficient charge / discharge capacity was obtained. It has been. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue remained 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 that did not gel and did not decrease the charge / discharge capacity was obtained.

(Example 15)
Lithium-nickel composite oxide powder was mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 40 g of CMC 1% solution by Niwataro Awatori. The amount of CMC deposited was 1.0% by weight. Lithium nickel composite oxide powder mixed with CMC (carboxymethylcellulose) 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 charging / discharging test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, the charge capacity was 210 mAh / g, the discharge capacity was 191 mAh / g, and even when compared with Comparative Example 11 in which CMC (carboxymethylcellulose) was not coated, there was no influence of coating, and sufficient charge / discharge capacity was obtained. It has been. Also, the impedance resistance is low and there is no problem. In the gelation test, no residue remained 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 that did not gel and did not decrease the charge / discharge capacity was obtained.

(Example 16)
Lithium-nickel composite oxide powder was mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 40 g of CMC 1% solution by Niwataro Awatori. The amount of CMC (carboxymethylcellulose) deposited was 1.0% by weight. Lithium nickel composite oxide powder mixed with CMC (carboxymethylcellulose) 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 charging / discharging test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, even when compared with Comparative Example 11 in which the charge capacity is 208 mAh / g, the discharge capacity is 190 mAh / g and the CMC is not coated, there is no influence of 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 remained 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 that did not gel and did not decrease the charge / discharge capacity was obtained.

(Example 17)
Lithium-nickel composite oxide powder was mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 40 g of CMC 1% solution by Niwataro Awatori. The amount of CMC (carboxymethylcellulose) deposited was 1.0% by weight. Lithium nickel composite oxide powder mixed with CMC (carboxymethylcellulose) 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 charging / discharging test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, the charge capacity of 205 mAh / g, the discharge capacity of 188 mAh / g and the comparative example 11 not coated with CMC 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 remained 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 that did not gel and did not decrease the charge / discharge capacity was obtained.

(Comparative Example 4)
Lithium-nickel composite oxide powder was mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 0.1 g of CMC 1% solution by Niwataro Awatori. The amount of CMC (carboxymethylcellulose) deposited was 0.0025% by weight. Lithium nickel composite oxide powder mixed with CMC (carboxymethylcellulose) 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 charging / discharging test and the gelation test were confirmed.

  The charge / discharge test of the secondary battery has a charge capacity of 215 mAh / g, a discharge capacity of 195 mAh / g, and a sufficient charge / discharge capacity with no influence of coating even when compared with Comparative Example 11 which does not cover CMC (carboxymethylcellulose). It has been. Also, the impedance resistance is low and there is no problem. However, in the gelation test, the result was that residual solids remained on the sieve by passing through a 250-micron sieve. As described above, gelation occurred, and an undesirable positive electrode active material for a nonaqueous electrolyte secondary battery was obtained.

(Comparative Example 5)
Lithium-nickel composite oxide powder was mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 0.1 g of CMC 1% solution by Niwataro Awatori. The amount of CMC (carboxymethylcellulose) deposited was 0.0025% by weight. Lithium nickel composite oxide powder mixed with CMC (carboxymethylcellulose) 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 charging / discharging test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, even when compared with Comparative Example 11 in which the charge capacity is 215 mAh / g, the discharge capacity is 195 mAh / g and the CMC is not coated, there is no influence of 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, the result was that residual solids remained on the sieve by passing through a 250-micron sieve. As described above, gelation occurred, and an undesirable positive electrode active material for a nonaqueous electrolyte secondary battery was obtained.

(Comparative Example 6)
Lithium-nickel composite oxide powder was mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 0.1 g of CMC 1% solution by Niwataro Awatori. The amount of CMC deposited was 0.0025% by weight. Lithium nickel composite oxide powder mixed with CMC (carboxymethylcellulose) 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 charging / discharging test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, even when compared with Comparative Example 11 in which the charge capacity is 215 mAh / g, the discharge capacity is 195 mAh / g and the CMC is not coated, there is no influence of 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, the result was that residual solids remained on the sieve by passing through a 250-micron sieve. As described above, gelation occurred, and an undesirable positive electrode active material for a nonaqueous electrolyte secondary battery was obtained.

(Comparative Example 7)
Lithium-nickel composite oxide powder was mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 60 g of CMC 1% solution by Niwataro Awatori. The amount of CMC (carboxymethylcellulose) deposited was 1.5% by weight. Lithium nickel composite oxide powder mixed with CMC (carboxymethylcellulose) 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 charging / discharging 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, the discharge capacity is 180 mAh / g, and CMC (carboxymethylcellulose) is not coated. Also, there is a problem that the impedance resistance increases. In the gelation test, no residue remained even after passing through a 250 micron sieve without gelation. Although it did not gel as described above, the charge / discharge capacity decreased and the impedance resistance also increased, and an undesirable positive electrode active material for a nonaqueous electrolyte secondary battery was obtained.

(Comparative Example 8)
Lithium-nickel composite oxide powder was mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 60 g of CMC 1% solution by Niwataro Awatori. The amount of CMC (carboxymethylcellulose) deposited was 1.5% by weight. Lithium nickel composite oxide powder mixed with CMC (carboxymethylcellulose) 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 charging / discharging 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, the discharge capacity is 180 mAh / g, and CMC (carboxymethylcellulose) is not coated. Also, there is a problem that the impedance resistance increases. In the gelation test, no residue remained even after passing through a 250 micron sieve without gelation. Although it did not gel as described above, the charge / discharge capacity decreased and the impedance resistance also increased, and an undesirable positive electrode active material for a nonaqueous electrolyte secondary battery was obtained.

(Comparative Example 9)
Lithium-nickel composite oxide powder was mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 60 g of CMC 1% solution by Niwataro Awatori. The amount of CMC (carboxymethylcellulose) deposited 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 charging / discharging 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, the discharge capacity is 180 mAh / g, and CMC (carboxymethylcellulose) is not coated. Also, there is a problem that the impedance resistance increases. In the gelation test, no residue remained even after passing through a 250 micron sieve without gelation. Although it did not gel as described above, the charge / discharge capacity decreased and the impedance resistance also increased, and an undesirable positive electrode active material for a nonaqueous electrolyte secondary battery was obtained.

(Comparative Example 10)
Lithium-nickel composite oxide powder was mixed with 40 g of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 and 20 g of CMC 1% solution by Niwataro Awatori. The amount of CMC (carboxymethylcellulose) deposited was 0.5% by weight. Lithium nickel composite oxide powder mixed with CMC was dried at room temperature to complete the coating. About the obtained lithium nickel complex oxide powder, the secondary battery charging / discharging test and the gelation test were confirmed.

  In the secondary battery charge / discharge test, even when compared with Comparative Example 11 in which the charge capacity is 215 mAh / g, the discharge capacity is 195 mAh / g and the CMC is not coated, there is no influence of the coating, and a sufficient charge / discharge capacity is obtained. However, there is a problem that the impedance resistance increases. In the gelation test, a residual solid content remained on the sieve by passing through a 250-micron sieve. As described above, the charge / discharge capacity was obtained, but the impedance resistance increased and gelled, and an undesirable positive electrode active material for a non-aqueous electrolyte secondary battery was obtained.

(Comparative Example 11)
Rechargeable battery charge / discharge test and gelation test confirmed for lithium nickel composite oxide powder that does not cover 40g CMC of general formula Li _1.03 Ni _0.85 Co _0.14 Al _0.01 did.

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

  Production conditions, charge capacity, discharge capacity, impedance resistance (represented as resistance in the table) and gelation test results (represented as gelation in the table) of the coated composite oxide particles of Examples and Comparative Examples. Table 3 shows. When the impedance resistance (shown as resistance in the table) is low and there is no problem, “OK” is indicated, and when the impedance resistance is increased as “NG”, the gelation test result (shown as gelation in the table). In this case, the case where gelation did not occur was designated as “OK”, and the case where gelation occurred was designated as “NG”.

  From the above results, if the coated composite oxide particles for the positive electrode active material for a non-aqueous electrolyte secondary battery are manufactured using the manufacturing method of the present embodiment, the secondary battery using this positive electrode active material is This is favorable because gelation can be prevented without reducing the discharge capacity.

  The nonaqueous electrolyte secondary battery of the present invention is suitable for the power source of small portable electronic devices (such as notebook personal computers and cellular phone terminals) that always require a high capacity. The nonaqueous electrolyte secondary battery of the present invention is suitable as a battery for an electric vehicle because it has excellent safety and can be reduced in size and increased in capacity.

Claims (6)

A heat treatment step of heating the composite hydroxide particles to obtain heat treated particles;
A firing step of mixing the heat treated particles with lithium or / and a lithium compound and firing to obtain composite oxide particles;
By mixing the composite oxide particles with 0.005 wt% or more and 1.0 wt% or less of carboxymethyl cellulose solution and leaving the mixture at 100 ° C. or more and 300 ° C. or less in a non-reducing gas atmosphere or vacuum atmosphere. A method for producing a coated composite oxide particle of a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising a coating step of obtaining a coated composite oxide particle. 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)
(Where, 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 0.1 ≦ z ≦ 0.4, 0 ≦ t ≦ 0.1, M is an additive element, and is at least one selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W The above elements.) The composite hydroxide particles are lithium 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).
LixNi _1-yz Co _y Me _z O ₂ (2)
(In the formula, 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 , At least one element selected from the group consisting of Ti and Ca.) Na concentration contained in the composite hydroxide particles is 0.2 wt% or more and 1.0 wt% 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 composite oxide particles according to any one of claims 1 to 4, wherein the heat treatment step is performed at 500 ° C or higher and 750 ° C or lower.   A nonaqueous electrolyte secondary battery using the coated composite oxide particles produced by the method for producing a coated composite oxide particle according to claim 1.