JP2015076154A - Positive electrode active material for nonaqueous electrolyte secondary batteries, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive electrode active material for nonaqueous electrolyte secondary batteries which enables the enhancement of the output characteristics and cycle characteristics of lithium ion secondary batteries.SOLUTION: A method for manufacturing a positive electrode active material for nonaqueous electrolyte secondary batteries comprises the steps of: producing a mixed slurry by preparing a slurry including complex hydroxide particles, of which the average particle diameter is in a range of 3.0-7.0 μm, and [(d90-d10)/MV] is 0.55 or less, adding a lithium compound to the slurry, and then wet-mixing the slurry; producing powder mixture by drying the mixed slurry; baking the powder mixture under a predetermined condition; and rinsing the resultant powder mixture by water, thereby producing a positive electrode active material for nonaqueous electrolyte secondary batteries which comprises particles of hexagonal crystal based lithium complex oxide expressed by the general formula, LiNiCoMnMOand having a layer structure, and of which the average particle diameter is in a range of 3-8 μm, [(d90-d10)/MV] is 0.60 or less, and [d90/MV] is 1.300 or less.

Description

  The present invention relates to a positive electrode active material for a non-aqueous electrolyte secondary battery comprising lithium nickel cobalt manganese composite oxide particles, a method for producing the same, and a non-aqueous electrolyte secondary battery using the positive electrode active material.

  In recent years, with the widespread use of portable electronic devices such as mobile phones and notebook computers, development of small and lightweight secondary batteries having high energy density is strongly desired. In addition, development of a high output secondary battery is strongly desired as a battery for electric vehicles including hybrid vehicles. As such a high output secondary battery, there is a lithium ion secondary battery. A lithium ion secondary battery includes a negative electrode, a positive electrode, an electrolyte, and the like, and a material capable of desorbing and inserting lithium is used as an active material for the negative electrode and the positive electrode.

  Such lithium ion secondary batteries are currently being actively researched and developed. Among them, lithium ion secondary batteries using layered or spinel type lithium metal composite oxides as positive electrode active materials are among them. Since the secondary battery can obtain a high voltage of 4V class, it is being put to practical use as a battery having a high energy density.

As a positive electrode active material of a lithium ion secondary battery, lithium cobalt composite oxide (LiCoO ₂ ), which is currently relatively easy to synthesize, lithium nickel composite oxide (LiNiO ₂ ) using nickel cheaper than cobalt, lithium Nickel cobalt manganese composite oxide (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ), lithium manganese composite oxide using manganese (LiMn ₂ O ₄ ), and the like are used. In particular, lithium nickel cobalt manganese composite oxide has attracted attention as a material that has good cycle characteristics and can take out high output with low resistance.

  In order for the positive electrode of the lithium ion secondary battery to exhibit high performance such as high cycle characteristics, low resistance, and high output, the positive electrode active material is composed of particles having a narrow particle size distribution and an appropriate particle size. It is necessary. This is because when the particle size distribution of the positive electrode active material is wide, the voltage applied to the particles in the electrode becomes non-uniform, and the fine particles are selectively deteriorated during repeated charging and discharging, resulting in a decrease in battery capacity. Because it occurs. In addition, particles having a large particle size have a small specific surface area. If such particles are used as the positive electrode active material, a sufficient reaction area with the electrolyte cannot be secured, resulting in an increase in positive electrode resistance and high output. This is because a secondary battery cannot be obtained.

  Therefore, in order to improve the performance of the positive electrode of the lithium ion secondary battery, the lithium nickel cobalt manganese composite oxide used as the positive electrode active material is manufactured to have a narrow particle size distribution and particles having an appropriate particle size. It is necessary to. Here, the lithium nickel cobalt manganese composite oxide is usually produced using a nickel cobalt manganese composite hydroxide as a precursor, and the particle properties thereof are strongly influenced by the particle properties of the composite hydroxide. For this reason, in order to obtain the above-mentioned positive electrode active material, it is important to have particles having a narrow particle size distribution and an appropriate particle size at the stage of the composite hydroxide.

  As a method for producing such a composite hydroxide, for example, International Publication No. W02004 / 092073 discloses that a nickel cobalt manganese salt aqueous solution, an alkali metal hydroxide aqueous solution, and an ammonium ion supplier are continuously or The reaction system is intermittently supplied to the reaction system, and while maintaining the temperature of the reaction system at a constant value in the range of 30 ° C. to 70 ° C., the reaction is allowed to proceed with the pH value maintained at a constant value in the range of 10 to 13. Thus, a method for synthesizing nickel cobalt manganese composite hydroxide particles composed of secondary particles in which primary particles are aggregated is described. In addition, in this document, after oxidizing nickel cobalt manganese composite oxyhydroxide particles by causing an oxidizing agent to act on composite hydroxide particles, dry mixing with lithium salt and firing in an oxygen-containing atmosphere, R It describes that lithium nickel cobalt manganese composite oxide particles having a -3m rhombohedral structure, high capacity, excellent cycle characteristics, and high safety can be obtained.

  On the other hand, in Japanese Patent Application Laid-Open No. 10-214624, a composite metal complex salt obtained by continuously supplying a complex metal salt aqueous solution, a complexing agent and a lithium hydroxide aqueous solution respectively to a reaction vessel is decomposed with lithium hydroxide to obtain lithium. The coprecipitation composite metal salt is precipitated, and the formation and decomposition of the composite metal complex salt is repeated while circulating in the tank, and the lithium coprecipitation composite metal salt is overflowed and taken out, so that the lithium coprecipitation having a substantially spherical particle shape is obtained. A method for synthesizing composite metal salts is described. Further, in this document, lithium coprecipitated composite metal salt is decomposed in a reducing atmosphere at 200 ° C. to 500 ° C., thereby synthesizing a lithium coprecipitated precursor oxide and firing it in an oxidizing atmosphere. Further, it is described that a positive electrode active material having a high packing density, a large capacity can be taken out, and further having a uniform composition on the molecular level and a sharp particle size distribution can be obtained.

  However, all of the methods described in these documents have obtained composite hydroxide particles that are precursors by continuous crystallization, so that the particle size distribution tends to become a normal distribution and spread on an industrial scale. Therefore, it is extremely difficult to obtain a positive electrode active material having a narrow particle size distribution and an appropriate particle size.

  In contrast to these documents, Japanese Patent Application Laid-Open No. 2011-116580 discloses a process in which a nucleation reaction mainly occurs (nucleation process) and a process in which a particle growth reaction mainly occurs (particles) in the production stage of composite hydroxide particles. A method of clearly separating the growth step) is described. According to such a method, generation of fine particles and coarse particles can be prevented, so that nickel cobalt manganese composite hydroxide particles having an appropriate particle size and a narrow particle size distribution can be obtained. Further, when a positive electrode active material is synthesized using nickel cobalt manganese composite hydroxide particles obtained by this method as a precursor, and a lithium ion secondary battery is constituted using this, a high initial discharge capacity of 150 mAh / g or more is obtained. Can be achieved.

  However, with the rapid development and spread of portable electronic devices and electric vehicles in recent years, higher output, higher capacity, and higher cycle characteristics are required for nonaqueous electrolyte secondary batteries. For this reason, development of the positive electrode active material which can improve these characteristics further is desired.

International Publication Number W02004 / 092073 Japanese Patent Laid-Open No. 10-214624 JP 2011-116580 A

The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention is as follows.
General formula (A): Li _{1 + u} Ni _a Co _b Mn _c M _d O ₂ (−0.05 ≦ u ≦ 0.15, a + b + c + d = 1, 0.3 ≦ a ≦ 0.8, 0.1 ≦ b ≦ 0.4, 0.1 ≦ c ≦ 0.4, 0 ≦ d ≦ 0.1, M is selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, W 1 or more elements) and is composed of hexagonal lithium nickel cobalt manganese composite oxide particles having a layered structure, having an average particle size in the range of 3.0 μm to 8.0 μm, and showing a broad particle size distribution An index [[d90-d10) / MV] is 0.60 or less, and [d90 / MV] is 1.300 or less, and a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery,
The crystallization reaction, the general formula _{(B): Ni a Co b} Mn c M d (OH) 2 + α (a + b + c + d = 1,0.3 ≦ a ≦ 0.8,0.1 ≦ b ≦ 0.4, 0.1 ≦ c ≦ 0.4, 0 ≦ d ≦ 0.1, 0 ≦ α ≦ 0.5, M is selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, W [(D90−d10) / MV], which is an index indicating the spread of the particle size distribution, is 0.55. The average particle size is in the range of 3.0 μm to 7.0 μm. A crystallization step to obtain nickel cobalt manganese composite hydroxide particles,
Slurry the nickel-cobalt-manganese composite hydroxide particles, add a lithium compound thereto and wet mix, and a mixing step to obtain a mixed slurry;
Drying the mixed slurry to obtain a mixed powder comprising nickel cobalt manganese composite hydroxide particles and a lithium compound;
Firing the mixed powder in an oxidizing atmosphere at 800 ° C. to 1000 ° C. to obtain lithium nickel cobalt manganese composite oxide particles;
And a water washing step of washing the lithium nickel cobalt manganese composite oxide particles with water.

The crystallization process includes
A plurality of metal compounds containing nickel, cobalt, and manganese in a pre-reaction aqueous solution adjusted to have a pH value of 12.0 or more measured on the basis of a liquid temperature of 25 ° C. and an ammonium ion concentration of 3 g / L to 25 g / L A nucleation step of forming a reaction aqueous solution by supplying an aqueous solution containing an aqueous solution containing an alkaline solution and an ammonium ion supplier to form a reaction aqueous solution,
After the nucleation step, the supply of the mixed aqueous solution, the aqueous solution containing the alkaline solution and the ammonium ion supplier is stopped, and the pH value measured on the basis of the liquid temperature of 25 ° C. is adjusted to 11.0 to 12.0. Then, while maintaining the pH value at 11.0 to 12.0, the aqueous solution containing the mixed aqueous solution, the alkaline solution and the ammonium ion supplier is supplied again to obtain the nucleation step. A particle growth process for growing the generated nuclei,
It is preferable to provide.

  The nickel cobalt manganese composite hydroxide particles obtained in the crystallization step are preferably filtered, washed with water, and further provided with a water washing step for dehydration. In this water washing step, the nickel cobalt manganese composite hydroxide particles are It is more preferable to wash with a device capable of washing without fixing on the filter medium.

  In the mixing step, it is preferable that the lithium compound is wet pulverized to form a lithium compound slurry and then wet mixed with the slurry containing the nickel cobalt manganese composite hydroxide particles. In particular, lithium carbonate is preferably used as the lithium compound, and the average particle size of the lithium carbonate is more preferably 10 μm or less.

  In the drying step, the mixed slurry is preferably dried by high frequency dielectric heating or microwave heating.

  In the firing step, the oxygen concentration in the oxidizing atmosphere is preferably 18% by volume to 100% by volume.

  It is preferable to further include a calcining step of calcining the mixed powder at a temperature of 350 ° C. to 780 ° C. before the calcining step.

  In the water washing step of the lithium nickel cobalt manganese composite oxide particles, the lithium nickel cobalt manganese composite oxide particles are charged into water having a mass ratio with respect to the lithium nickel cobalt manganese composite oxide particles of 0.5 to 1.0. It is preferable to make the slurry, wash with water, and then filter and dry the slurry.

Positive electrode active material for non-aqueous electrolyte secondary battery of the present invention, the obtained by the process, the general formula _{(A): Li 1 + u} Ni a Co b Mn c M d O 2 (-0.05 ≦ u ≦ 0.15, a + b + c + d = 1, 0.3 ≦ a ≦ 0.8, 0.1 ≦ b ≦ 0.4, 0.1 ≦ c ≦ 0.4, 0 ≦ d ≦ 0.1, M is Mg , One or more elements selected from Ca, Al, Ti, V, Cr, Zr, Nb, Mo, W), and a hexagonal lithium nickel cobalt manganese composite oxide particle having a layered structure, [(D90-d10) / MV] is 0.60 or less and [d90 / MV] is 1.0 or less, which is an index indicating the spread of the particle size distribution, having an average particle size in the range of 3.0 μm to 8.0 μm. 300 or less.

  The nonaqueous electrolyte secondary battery of the present invention includes a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte, and the positive electrode active material for a nonaqueous electrolyte secondary battery is used as a positive electrode material of the positive electrode. It is characterized by. In particular, the nonaqueous electrolyte secondary battery of the present invention has the characteristics that the initial discharge capacity is 160.0 mAh / g or more, the positive electrode resistance ratio is 1.00 or less, and the capacity retention after 500 cycles is 85% or more. .

  According to the present invention, a positive electrode active material having an average particle size in the range of 3.0 μm to 8.0 μm and a narrow particle size distribution can be industrially produced with high productivity. Moreover, when this positive electrode active material is used as a positive electrode material for a non-aqueous electrolyte secondary battery, it is possible to increase the capacity of the secondary battery and reduce the positive electrode resistance and improve the cycle characteristics.

  Such a non-aqueous electrolyte secondary battery (lithium ion secondary battery) using the positive electrode active material of the present invention is an electric vehicle such as a portable electronic device such as a mobile phone or a laptop computer, a power tool, and a hybrid vehicle. Therefore, the industrial significance is extremely large because it satisfies the demands of high power, high capacity and high cycle characteristics required for small secondary batteries mounted on power supply devices such as the above.

FIG. 1 is a schematic flow diagram showing a process of producing composite hydroxide particles that are precursors of a positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention. FIG. 2 is a schematic flow diagram of the process for producing the positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention. It is a SEM photograph (observation magnification 1,000 times) of the positive electrode active material for nonaqueous electrolyte secondary batteries of this invention. FIG. 4 is a cross-sectional view of a 2032 type coin battery used for battery evaluation. FIG. 5 is an explanatory diagram regarding the internal resistance of the coin battery using a Nyquist plot obtained by AC impedance measurement.

  In view of the above-mentioned problems, the present inventors have made extensive studies on a method for producing lithium nickel cobalt manganese composite oxide particles (hereinafter referred to as “lithium composite oxide particles”) constituting the positive electrode active material. As a result, conventionally, mixing of nickel cobalt manganese composite hydroxide particles (hereinafter referred to as “composite hydroxide particles”) and a lithium compound has been performed by dry mixing. Even when composite hydroxide particles having a narrow particle size distribution are used, it is inevitable that the lithium compound is unevenly distributed in the lithium mixture composed of the composite hydroxide particles and the lithium compound. For this reason, when this lithium mixture is fired, abnormal grain growth is caused during the firing process, and the presence of lithium composite oxide particles formed by this abnormal grain growth is the battery characteristic of the nonaqueous electrolyte secondary battery. The knowledge that it is having a bad influence on was obtained.

  Based on such knowledge, the present invention makes the mixing process conventionally performed in a dry process wet, and reviews and optimizes the manufacturing conditions in each process, thereby causing uneven distribution of lithium compounds and the resulting The lithium composite oxide particles are prevented from being coarsened, thereby improving the battery characteristics of the obtained nonaqueous electrolyte secondary battery.

  Hereinafter, the present invention is divided into (1) a method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery, (2) a positive electrode active material for a nonaqueous electrolyte secondary battery, and (3) a nonaqueous electrolyte secondary battery. This will be described in detail.

(1) TECHNICAL FIELD The present invention of the positive electrode active material for a nonaqueous electrolyte secondary battery is represented by the general formula _{(A): Li 1 + u} Ni a Co b Mn c M d O 2 (-0.05 ≦ u ≦ 0. 15, a + b + c + d = 1, 0.3 ≦ a ≦ 0.8, 0.1 ≦ b ≦ 0.4, 0.1 ≦ c ≦ 0.4, 0 ≦ d ≦ 0.1, M is Mg, Ca 1 or more elements selected from Al, Ti, V, Cr, Zr, Nb, Mo, and W), and a hexagonal lithium composite oxide particle having a layered structure. [(D90-d10) / MV] is 0.60 or less, and [d90 / MV] is 1.300 or less, which is an index indicating the spread of the particle size distribution in the range of 0.0 μm to 8.0 μm. The present invention relates to a method for producing a positive electrode active material for a water electrolyte secondary battery.

(1-a) Crystallization Step The crystallization step is a step of obtaining composite hydroxide particles that are precursors of the lithium composite oxide particles represented by the general formula (A). Specifically, the general formula (B): Ni _a Co _b Mn _c M _d (OH) _{2 + α} (a + b + c + d = 1, 0.3 ≦ a ≦ 0.8, 0.1 ≦ b ≦ 0.4, 0.1 ≦ c ≦ 0.4, 0 ≦ d ≦ 0.1, 0 ≦ α ≦ 0.5, M is selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, W And a composite hydroxide particle represented by one or more elements.

  The method for producing such composite hydroxide particles is not particularly limited, and can be obtained by a general crystallization process. However, in order to obtain lithium composite oxide particles having the average particle size and particle size distribution required for the positive electrode active material of the present invention, the composite hydroxide particles have an average particle size of 3.0 μm to 7.0 μm, and a particle size distribution. It is necessary to control [(d90−d10) / MV], which is an index indicating the spread of, to be 0.55 or less. Therefore, in the present invention, the nucleation of composite hydroxide particles takes precedence, the nucleation step in which the growth of nuclei hardly proceeds, and the particle growth step in which only the nucleation proceeds and almost no new nuclei are generated. It is preferable to perform the crystallization process by clearly separating into the two stages. According to such a method, the composite hydroxide particles having the above average particle size and particle size distribution can be efficiently obtained without classifying the obtained composite hydroxide particles after the crystallization step. Can do.

(Nucleation process)
First, a plurality of metal compounds containing nickel, cobalt, manganese and an additive element (M) are dissolved in water at a predetermined ratio to prepare a mixed aqueous solution. In the present invention, the composition ratio of the metal element in the obtained composite hydroxide particles is the same as the composition ratio of the metal element in the mixed aqueous solution. Therefore, the ratio of each metal compound is adjusted so that the composition ratio of the metal element in the mixed aqueous solution becomes the composition ratio of the metal element in the target composite hydroxide particles, thereby preparing the mixed aqueous solution. The temperature of the mixed aqueous solution is preferably adjusted to 20 ° C. to 60 ° C., more preferably 35 ° C. to 60 ° C., similarly to the aqueous solution before reaction described later.

  On the other hand, an alkaline solution such as an aqueous sodium hydroxide solution, an aqueous solution containing an ammonium ion supplier and water are supplied to the reaction vessel and mixed to prepare a pre-reaction aqueous solution. At this time, an alkali metal hydroxide aqueous solution such as sodium hydroxide or potassium hydroxide can be used as the alkali solution. As the aqueous solution containing the ammonium ion supplier, ammonia water, ammonium chloride aqueous solution, ammonium sulfate aqueous solution, ammonium carbonate aqueous solution and the like can be used. From the viewpoint of cost and ease of handling, aqueous ammonia can be used. preferable.

  The supply amount of the alkaline solution may be adjusted so that the pH value of the aqueous solution before reaction measured on the basis of the liquid temperature of 25 ° C. is 12.0 or more, preferably 12.5 or more, more preferably 12.8 or more. Necessary. When the pH value is less than 12.0, a growth reaction of the produced nuclei occurs with nucleation, and the particle size distribution of the resulting composite hydroxide particles becomes wide. Note that the upper limit of the pH value is not particularly limited, but if the pH value is too high, the nuclei to be produced become finer and the reaction aqueous solution described later may gel, so about 14.0. It is preferable that

  The supply amount of the aqueous solution containing the ammonium supplier is adjusted so that the ammonium ion concentration in the aqueous solution before reaction is preferably 3 g / L to 25 g / L, more preferably 5 g / L to 15 g / L. If the ammonium ion concentration is less than 3 g / L, the solubility of metal ions cannot be kept constant, and composite hydroxide particles having a uniform shape and particle size cannot be formed. It is easy to produce and the particle size distribution is widened. On the other hand, when it exceeds 25 g / L, the solubility of metal ions becomes too high, so that the composite hydroxide particles to be crystallized become fine, the lithium composite oxide particles finally obtained become fine, and the specific surface area is also large. There is a risk of becoming smaller. Further, the amount of metal ions remaining in the reaction aqueous solution increases, resulting in a compositional shift. Note that if the ammonium ion concentration fluctuates during the nucleation step, the solubility of metal ions fluctuates and uniform composite hydroxide particles are not formed. Therefore, it is preferable to maintain a constant value. For example, the ammonium ion concentration is preferably maintained at a predetermined concentration with the upper and lower limits being about 5 g / L.

  Moreover, the liquid temperature of the aqueous solution before reaction is preferably adjusted to 20 ° C to 60 ° C, more preferably 35 ° C to 60 ° C. If the temperature of the aqueous solution before the reaction is less than 20 ° C., the solubility of metal ions is too low, so that nucleation is likely to occur and control becomes difficult. On the other hand, when the temperature exceeds 60 ° C., volatilization of ammonia is promoted, so that an excess ammonium ion supplier must be supplied in order to maintain a predetermined ammonium ion concentration, resulting in an increase in production cost. The pH value of the liquid in the reaction tank and the concentration of ammonium ions can be measured with a general pH meter and ion meter, respectively.

  As described above, the mixed aqueous solution is supplied into the reaction vessel while stirring the pre-reaction aqueous solution whose pH value, ammonium ion concentration and liquid temperature are adjusted. Thereby, a reaction aqueous solution in which the pre-reaction aqueous solution and the mixed aqueous solution are uniformly mixed is formed in the reaction tank, and fine nuclei of composite hydroxide particles are generated in the reaction aqueous solution. At this time, since the pH value of the reaction aqueous solution is in the above range, the produced nuclei hardly grow and the production of nuclei takes place preferentially.

  In addition, since the pH value and ammonium ion concentration of the reaction aqueous solution change with the nucleation, the aqueous solution containing the alkaline solution and the ammonium ion supplier is continuously supplied together with the mixed aqueous solution. By controlling the concentration to be maintained at a predetermined value, new nuclei can be generated continuously. And a nucleation process is complete | finished when a predetermined amount of nucleus is produced | generated in reaction aqueous solution. Whether or not a predetermined amount of nuclei has been generated can be determined by the amount of metal compound supplied to the reaction aqueous solution.

  The amount of nuclei generated in the nucleation step is not particularly limited, but in order to obtain composite hydroxide particles having a narrow particle size distribution, the total amount supplied to obtain a predetermined amount of composite hydroxide particles is not limited. The amount of the metal compound is preferably 0.1% to 2.0%, more preferably 1.5% or less.

(Particle growth process)
In the particle growth step, after a predetermined amount of nuclei is generated in the nucleation step, the supply of the aqueous solution containing the mixed aqueous solution, the alkali solution and the ammonium ion supplier is temporarily stopped, and the pH value measured on the basis of the liquid temperature of 25 ° C. After adjusting to 11.0 to 12.0, the supply of the aqueous solution containing the mixed aqueous solution, the alkaline solution and the ammonium ion supplier is restarted so that the pH value is maintained in the above range, and the nucleus is grown. At this time, the pH value of the reaction aqueous solution is preferably adjusted by adding the same kind of inorganic acid as the acid constituting the metal compound. Specifically, when using a sulfate as the metal compound, it is preferable to adjust the pH value by adding sulfuric acid to the reaction aqueous solution.

  The pH value of the aqueous reaction solution in the particle growth step is adjusted to 11.0 to 12.0, preferably 11.4 to 11.8, more preferably 11.5 to 11.7. By adjusting the pH value of the aqueous reaction solution to the above range, not only can the average particle size of the resulting composite hydroxide particles be controlled within a predetermined range, but also new nuclei are generated during the particle growth process. Since this can be suppressed, the particle size distribution of the resulting composite hydroxide particles can be narrowed. However, when the pH value is less than 11.0, the solubility of the reaction aqueous solution increases due to the action of ammonium ions, and the metal ions remaining in the reaction aqueous solution without being precipitated increase. On the other hand, if the pH value exceeds 12.0, new nuclei are generated during the particle growth step, and the resulting composite hydroxide particles have a wide particle size distribution.

  In addition, when the pH value is 12.0, it is a boundary condition between nucleation and nucleation, so it should be either nucleation process or particle growth process depending on the presence or absence of nuclei present in the reaction aqueous solution. Can do. That is, when the pH value of the nucleation step is higher than 12.0 to generate a large amount of nuclei and then the pH value is set to 12.0 in the particle growth step, a large amount of nuclei exist in the reaction aqueous solution. The growth of nuclei takes precedence and composite hydroxide particles with a narrow particle size distribution are obtained. On the other hand, when no nuclei exist in the reaction aqueous solution, that is, when the pH value is set to 12.0 in the nucleation step, there is no nucleus to grow, so nucleation occurs preferentially, and the pH value of the particle growth step By making the value smaller than 12.0, the produced nuclei grow and composite hydroxide particles having a narrow particle size distribution can be obtained. In any case, the pH value of the particle growth process may be controlled to a value lower than the pH value of the nucleation process.

  The particle size of the resulting composite hydroxide particles can be controlled by crystallization conditions such as the time of the particle growth stage, the pH value during nucleation, and the amount of nuclei produced during the nucleation stage. Specifically, it can be controlled to an arbitrary size by appropriately adjusting the liquid amounts in the nucleation stage and the particle growth stage. In addition, the particle size can be controlled by controlling the power for the stirring station per unit volume of the aqueous reaction solution. For example, the particle size can be increased by reducing the power required for stirring.

  In the case of the above method, in both steps, the metal ions are crystallized as nuclei or composite hydroxide particles, so that the ratio of the liquid component to the metal component in each reaction aqueous solution increases. In this case, apparently, the concentration of the mixed aqueous solution to be supplied is lowered, and there is a possibility that the composite hydroxide particles are not sufficiently grown particularly in the particle growth step. In such a case, it is preferable to discharge a part of the reaction aqueous solution to the outside of the reaction tank after completion of the nucleation step or in the middle of the particle growth step. Specifically, the supply of the mixed aqueous solution to the reaction aqueous solution and the stirring are stopped, the nucleus and the composite hydroxide particles are allowed to settle, and the supernatant of the reaction aqueous solution is discharged, whereby the mixed aqueous solution relative to the reaction aqueous solution is discharged. Concentration can be increased. As a result, since the composite hydroxide particles can be grown in a state where the relative concentration is high, the particle size distribution can be made narrower, and the density of the composite hydroxide particles can be increased.

(1-b) Water-washing step In the present invention, it is preferable to further include a water-washing step of filtering, washing, and dehydrating the composite hydroxide particles obtained in the crystallization step.

  The means for filtration and washing with water is not particularly limited as long as the impurities precipitated together with the composite hydroxide particles in the reaction aqueous solution can be sufficiently removed. For example, a washing method in which concentration and dilution are repeated, and sedimentation is separated, and dewatering and repulp washing using a filter press (washing method in which water is added and then washed again after discarding the supernatant used for washing) are repeated. Cleaning methods can be used. However, in these methods, since the amount of water used is large and it takes a long time for the generated particles to settle, not only the productivity is bad, but also considerable effort is required to recover and reslurry the cake. There is a problem. For this reason, in the present invention, it is preferable to obtain composite hydroxide particles by washing and dewatering with an apparatus capable of washing without fixing the object on the filter medium, such as a continuous pressure filter. Examples of such a method include a rotary filter.

  Also, the dehydrating means is not particularly limited, and known means such as a vacuum dryer can be used in addition to means for continuously washing and dewatering using the aforementioned continuous pressure filter.

  In addition, when performing the mixing process described later by general dry mixing, it is essential to dry the composite hydroxide particles after dehydration, but when performing the mixing process by wet mixing as in the present invention, In particular, when the steps from the crystallization step to the firing step are performed continuously, the composite hydroxide particles after dehydration may be slurried without drying.

(1-c) Mixing step The mixing step is a step in which composite hydroxide particles are slurried, a lithium compound is added thereto and wet-mixed to obtain a mixed slurry.

  Conventionally, in such a mixing step, moisture remaining in the particles until the firing step is reduced to a certain amount, and the number of atoms of each metal component in the obtained positive electrode active material and the ratio of the number of lithium atoms vary. From the viewpoint of preventing the occurrence and stabilizing the lithium atom number ratio (Li / Me), a dry mixing method has been adopted. Specifically, the composite hydroxide particles obtained in the crystallization step were dried (heat treatment), a lithium compound was added thereto, and dry mixing was performed to obtain a mixed powder.

  However, such dry mixing cannot avoid the uneven distribution of lithium compounds as described above. When the lithium mixture is fired in this state, abnormal grain growth of the lithium composite oxide particles is caused from the locally localized lithium compound as a starting point. As a result, even when the average particle size or particle size distribution is controlled within a predetermined range, the presence of abnormally grown lithium composite oxide particles can sufficiently improve the battery characteristics of the obtained secondary battery. There were cases where it was not possible.

  On the other hand, in the present invention, by mixing the mixing process with wet mixing, the uneven distribution of the lithium compound and the abnormal grain growth of the lithium composite oxide particles in the firing process due to this can be prevented and obtained. The battery characteristics of the secondary battery can be further improved. Specifically, a solvent is added to the composite hydroxide particles obtained in the crystallization step to form a slurry containing composite hydroxide particles (hereinafter referred to as “composite hydroxide slurry”). A mixed slurry is obtained by adding a lithium compound and performing wet mixing.

  As the solvent added to the composite hydroxide particles, water or an organic solvent can be used, but from the viewpoint of easy handling, it is preferable to use water, and it is particularly preferable to use purified water such as pure water. .

  In the mixing of the composite hydroxide slurry and the lithium compound, the number of lithium atoms (Li) relative to the sum (Me) of the number of atoms of nickel, cobalt, manganese and the additive element (M) in the obtained lithium composite oxide particles ) Ratio (Li / Me) is 0.95 to 1.15, preferably 1.00 to 1.10. When Li / Me is less than 0.95, the positive electrode resistance in the nonaqueous electrolyte secondary battery using the obtained lithium composite oxide particles as the positive electrode material is increased, so that the output characteristics are deteriorated. On the other hand, when Li / Me exceeds 1.15, the initial discharge capacity of the non-aqueous electrolyte secondary battery is lowered.

  The lithium compound used at this time can be added to the composite hydroxide slurry as it is in powder form, but in order to enable more uniform mixing, after adding a solvent to the lithium compound and slurrying, It is preferable to add to the composite hydroxide slurry. Even in this case, from the viewpoint of ease of handling, it is preferable to slurry the lithium compound using water, particularly purified water such as pure water, as the solvent. The lithium compound is not particularly limited. For example, lithium hydroxide, lithium nitrate, lithium carbonate, or a mixture thereof can be used. When the lithium compound is slurried with water, It is preferable to use slightly water-soluble lithium carbonate.

  Further, when the average particle size of the composite hydroxide particles contained in the composite hydroxide slurry is about 3.0 μm to 5.0 μm, the lithium compound is wet pulverized with a bead mill or the like before the mixing step. The average particle size is preferably adjusted to 10 μm or less, more preferably 5 μm or less. Thus, by making the average particle diameter of the composite hydroxide particles and the lithium compound approximate, more uniform mixing becomes possible.

  In addition, the moisture content of the composite hydroxide slurry, the lithium compound slurry, and the mixed slurry during wet mixing is preferably adjusted to 10% by mass to 40% by mass, more preferably 20% by mass to 30% by mass. To do. If the moisture content is less than 10% by mass, the effect of wet mixing cannot be sufficiently obtained, and uneven distribution of lithium cannot be prevented. On the other hand, when it exceeds 40 mass%, it takes a long time to dry the mixed slurry, and the productivity deteriorates.

  The mixing means is not particularly limited as long as it can be wet-mixed. For example, a shaker mixer, a Laedige mixer, a Julia mixer, a V blender, or the like can be used. Mix well enough that the sculpture is not destroyed. For example, when using a shaker mixer, the composite hydroxide slurry adjusted to a moisture content in the above range and a lithium compound are charged into the shaker mixer, the rotation speed is 80 rpm to 90 rpm, and the mixing time is 0.2 hours to By mixing for 0.5 hours, a uniform mixed slurry can be obtained.

(1-d) Drying step The drying step is a step of drying the mixed slurry to obtain a mixed powder composed of composite hydroxide particles and a lithium compound.

  The drying method is not particularly limited, and a known method can be used. However, drying can be performed in a short time compared to general air drying, and there is no dry aggregation and after drying. A drying method by high frequency dielectric heating or microwave heating is preferred, which does not require crushing. In the high frequency dielectric heating, a frequency of 4 MHz to 80 MHz is usually used, and in the microwave heating, a frequency of 2450 MHz is usually used. On the other hand, the output and heating time at the time of heating are not particularly limited, and should be appropriately set according to the properties and processing amount of the target mixed slurry.

(1-e) calcination step Before the firing step described below, the mixed powder obtained in the drying step is 350 ° C to 780 ° C, preferably 400 ° C to 750 ° C, preferably 1 hour to 10 hours, preferably It is preferable to perform calcination by holding for 2 hours to 5 hours, and subsequently to perform a baking step. This is because lithium composite oxide particles having a uniform crystal structure can be obtained in the firing step by maintaining the temperature near the melting point of the lithium compound or near the reaction temperature and sufficiently diffusing lithium.

(1-f) Firing step In the firing step, the mixed powder obtained by the drying step is heated in an oxidizing atmosphere at 800 ° C to 1000 ° C to react the composite hydroxide particles with the lithium compound, This is a step of obtaining lithium composite oxide particles.

  The atmosphere in the firing step needs to be an oxidizing atmosphere, and is preferably an atmosphere having an oxygen concentration of 18% by volume to 100% by volume. Considering the cost, it is in an air stream (oxygen concentration: 21% by volume). Is more preferable. When the oxygen concentration is less than 18% by volume, sufficient oxidation cannot be performed, and the crystallinity of the lithium composite oxide particles becomes nonuniform.

  The firing temperature is 800 ° C to 1000 ° C, preferably 850 ° C to 1000 ° C. When the firing temperature is less than 800 ° C., the diffusion of lithium into the composite hydroxide particles becomes insufficient, and surplus lithium and unreacted composite hydroxide particles remain, or the crystal structure becomes non-uniform. As a result, sufficient battery characteristics cannot be obtained. On the other hand, when the firing temperature exceeds 1000 ° C., the lithium composite oxide particles to be generated sinter violently, and abnormal particle growth is caused, resulting in an increase in the proportion of coarse particles. For this reason, it becomes impossible to control the average particle size and particle size distribution of the obtained lithium composite hydroxide particles within a predetermined range, and further, the form of secondary particles cannot be maintained, which causes problems such as a decrease in battery capacity. Occurs.

  The firing time is preferably 1 hour or longer, more preferably 5 to 15 hours. When the firing time is less than 1 hour, the lithium composite oxide particles may not be sufficiently generated.

  The rate of temperature rise is preferably 3 ° C / min to 10 ° C / min, more preferably 4 ° C / min to 6 ° C / min. When the rate of temperature rise is less than 3 ° C./min, the firing time becomes longer and the productivity is lowered. On the other hand, when it exceeds 10 ° C./min, the difference between the furnace temperature and the temperature of the composite hydroxide particles becomes large, and the reaction with lithium may not sufficiently proceed.

  The furnace used in the firing step is not particularly limited as long as the mixed powder can be heated in the atmosphere or in an oxygen stream. However, an electric furnace that does not generate gas is preferable, and a batch type or continuous type is preferable. Any of the furnaces can be used.

(1-g) Water washing step In the present invention, after the firing step, the obtained lithium composite oxide particles are washed with water, and an excess lithium compound, particularly carbonated lithium, adhering to the surface of the lithium composite oxide particles. It is necessary to remove the compound. Thereby, it can prevent that the capacity | capacitance of the nonaqueous electrolyte secondary battery obtained falls.

  Such a water washing method is not particularly limited, but from the viewpoint of efficiently removing the lithium compound, a predetermined amount of water is mixed with the lithium composite oxide particles to form a slurry, which is then washed with water. Preferably, the slurry is filtered and dried.

  Under the present circumstances, the quantity of the water mixed with lithium composite oxide particle is mass ratio with respect to this lithium composite oxide particle, Preferably it is 0.5-1.0, More preferably, you may be 0.6-1.0. If it is less than 0.5, the slurry concentration becomes too high, and uniform stirring may be difficult. On the other hand, when it exceeds 1.0, lithium may elute from the inside of the lithium composite oxide particles, and Li / Me may decrease.

(2) Cathode Active Material for Nonaqueous Electrolyte Secondary Battery The cathode active material for a nonaqueous electrolyte secondary battery of the present invention is obtained by the above production method, and has the general formula (A): Li _{1 + u} Ni _a Co _b Mn _c M _d O ₂ (−0.05 ≦ u ≦ 0.15, a + b + c + d = 1, 0.3 ≦ a ≦ 0.8, 0.1 ≦ b ≦ 0.4, 0.1 ≦ c ≦ 0.4, 0 ≦ d ≦ 0.1, where M is one or more elements selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W) and has a layered structure [(D90−d10) / MV], which is an index indicating the spread of the particle size distribution, is 0.60 or less, and is composed of a lithium-based lithium composite oxide particle, having an average particle size in the range of 3.0 μm to 8.0 μm. [D90 / MV] is 1.300 or less.

(2-a) Composition The value of u indicating the excess amount of lithium (Li) is -0.05 to 0.15, preferably 0 to 0.15, more preferably 0.02 to 0.12. When the value of u is less than −0.05, the positive electrode resistance in the nonaqueous electrolyte secondary battery increases, and the battery output decreases. On the other hand, if it exceeds 0.15, the initial discharge capacity of the nonaqueous electrolyte secondary battery will be reduced.

  Nickel (Ni) is an additive element that contributes to an improvement in battery capacity. The value of a indicating the nickel content is 0.3 to 0.8, preferably 0.4 to 0.6, and more preferably 0.45 to 0.55. If the value of a is less than 0.3, the battery capacity of the nonaqueous electrolyte secondary battery using this positive electrode active material will be reduced. On the other hand, if it exceeds 0.8, the amount of other additive elements may decrease, and the effect of addition may not be sufficiently obtained.

  Cobalt (Co) is an additive element that contributes to improving the cycle characteristics. The value b indicating the cobalt content is 0.1 to 0.4, preferably 0.2 to 0.3, and more preferably 0.23 to 0.28. If the value of b is less than 0.1, sufficient cycle characteristics cannot be obtained, and the capacity retention rate decreases. On the other hand, if it exceeds 0.4, the initial discharge capacity is greatly reduced.

  Manganese (Mn) is an additive element that contributes to the improvement of thermal stability. The value of c indicating the manganese content is 0.1 to 0.4, preferably 0.2 to 0.3, and more preferably 0.23 to 0.28. If the value of c is less than 0.1, the effect of addition cannot be sufficiently obtained. On the other hand, if it exceeds 0.4, the initial discharge capacity is greatly reduced.

  Furthermore, in the positive electrode active material of the present invention, the lithium composite oxide particles can contain an additive element (M). By including the additive element (M), it is possible to improve durability and output characteristics of a secondary battery using this as a positive electrode active material.

  Examples of such additive elements (M) include magnesium (Mg), calcium (Ca), aluminum (Al), titanium (Ti), vanadium (V), chromium (Cr), zirconium (Zr), and niobium (Nb). One or more elements selected from molybdenum (Mo) and tungsten (W) can be used. Selection of these additive elements (M) is appropriately selected according to the application of the secondary battery in which the positive electrode active material to be obtained is used and the required performance.

  The value of d indicating the content of the additive element (M) is 0.1 or less. If the value of d exceeds 0.1, the metal element that contributes to the Redox reaction decreases, and the battery capacity decreases.

  The additive element (M) can be crystallized together with nickel, cobalt and manganese in the crystallization step and can be uniformly dispersed in the composite hydroxide particles. The additive element (M) may be coated on the surface. Moreover, in a mixing process, it is also possible to mix with a lithium compound with a composite hydroxide particle, You may use these methods together. Regardless of which method is used, it is necessary to adjust the content so as to achieve the composition of the above general formula.

(2-b) Particle Structure The positive electrode active material of the present invention is composed of lithium composite oxide particles composed of substantially spherical secondary particles formed by aggregating a plurality of primary particles. The shape of the primary particles constituting the secondary particles can take various forms such as a plate shape, a needle shape, a rectangular parallelepiped shape, an elliptical shape, and a ridge shape, and the aggregation state also aggregates in a random direction. In addition to the case, the present invention can also be applied to the case where the major axis direction of particles aggregates radially from the center. However, in order to improve the filling property of the positive electrode active material, the shape of the secondary particles is preferably spherical.

  Moreover, the positive electrode active material of the present application is characterized in that lithium is uniformly distributed without being unevenly distributed. For this reason, in the positive electrode active material of the present invention, there are almost no lithium composite oxide particles that have grown abnormally in the firing step. This indicates that the positive electrode active material of the present invention is an index indicating the spread of the particle size distribution, which will be described later, [(d90-d10) / MV] is 0.60 or less, and [d90 / MV] is 1. It can be confirmed from the fact that it is 300 or less.

(2-c) Average particle diameter (MV)
The positive electrode active material of the present invention has an average particle size of 3.0 μm to 8.0 μm, preferably 3 from the viewpoint of improving the battery capacity, safety, and output characteristics of the obtained nonaqueous electrolyte secondary battery. It is necessary to be in the range of 0.0 μm to 5.0 μm, more preferably 3.5 μm to 4.0 μm. Here, the average particle diameter means a volume-based average particle diameter (MV) obtained by a laser diffraction scattering method.

  When the average particle size is less than 3.0 μm, the packing density of the positive electrode active material is lowered, so that the battery capacity per positive electrode volume is lowered. On the other hand, when it exceeds 8.0 μm, the specific surface area of the positive electrode active material is reduced, and the interface between the positive electrode active material and the electrolytic solution is reduced, so that the resistance of the positive electrode is increased and the output characteristics are deteriorated.

(2-d) Particle Size Distribution In the positive electrode active material of the present invention, [(d90-d10) / MV], which is an index indicating the spread of particle size distribution, is 0.60 or less, and [d90 / MV] is 1.300 or less. Since such a positive electrode active material has a very small ratio of fine particles and coarse particles, the safety, cycle characteristics, and output characteristics of the obtained secondary battery can be improved. Here, d10 in [(d90-d10) / MV] and [d90 / d10] is the total volume of all particles when the number of particles in each particle size is accumulated from the smaller particle size. Means a particle size of 10%. Moreover, d90 means the particle size in which the cumulative volume becomes 90% of the total volume of all particles when the number of particles in each particle size is accumulated from the smaller particle size. The method for obtaining d90 and d10 is not particularly limited. For example, it can be obtained from the volume integrated value measured by a laser light diffraction / scattering particle size analyzer.

  When [(d90-d10) / MV] exceeds 0.60, there are many fine particles having a very small particle size with respect to the average particle size and coarse particles having a very large particle size with respect to the average particle size. It will be. When a positive electrode is formed using a positive electrode active material in which a large amount of fine particles are present, the secondary battery may generate heat due to a local reaction of the fine particles, and the fine particles may be selectively deteriorated. As a result, the cycle characteristics deteriorate. In addition, when the positive electrode is configured using a positive electrode active material in which a large amount of coarse particles are present, the positive electrode resistance increases due to the fact that a sufficient reaction area between the electrolytic solution and the positive electrode active material cannot be secured. Characteristics deteriorate. When [d90 / MV] exceeds 1.300, even when [(d90-d10) / MV] is 0.60 or less, the positive electrode resistance similarly increases, and the output characteristics deteriorate.

  In order to further reduce the proportion of fine particles and coarse particles in the positive electrode active material, [(d90-d10) / MV] is preferably 0.55 or less, and preferably 0.50 or less. Is more preferable. [D90 / MV] is preferably 1.290 or less, and more preferably 1.250 or less.

(3) Non-aqueous electrolyte secondary battery The non-aqueous electrolyte secondary battery of the present invention comprises a positive electrode, a negative electrode, a separator, a non-aqueous electrolyte, and the like, and is composed of the same components as a general non-aqueous electrolyte secondary battery. The The embodiment described below is merely an example, and the nonaqueous electrolyte secondary battery of the present invention can be variously modified based on the knowledge of those skilled in the art based on the embodiment described in the present specification. It can be implemented in an improved form. Moreover, the use of the nonaqueous electrolyte secondary battery of the present invention is not particularly limited.

(3-a) Positive Electrode Using the positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention, for example, a positive electrode of a non-aqueous electrolyte secondary battery is produced as follows.

  First, a powdered positive electrode active material, a conductive material, and a binder are mixed, and activated carbon and a target solvent such as viscosity adjustment are added as necessary, and this is kneaded to prepare a positive electrode mixture paste. . At that time, the mixing ratio in the positive electrode mixture paste is also an important factor for determining the performance of the nonaqueous electrolyte secondary battery. 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 is 60 parts by mass to 95 parts by mass as in the case of the positive electrode of a general nonaqueous electrolyte secondary battery. The content is preferably 1 part by mass to 20 parts by mass, and the content of the binder is preferably 1 part by mass to 20 parts by mass.

  The obtained positive electrode mixture paste is applied to, for example, the surface of a current collector made of aluminum foil and dried to disperse the solvent. If necessary, pressurization may be performed by a roll press or the like to increase the electrode density. In this way, a sheet-like positive electrode can be produced. The sheet-like positive electrode can be cut into an appropriate size according to the target battery and used for battery production. However, the method for manufacturing the positive electrode is not limited to the above-described examples, and other methods may be used.

  In producing the positive electrode, as the conductive material, 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 anchoring the active material particles. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), fluorine rubber, ethylene propylene diene rubber, styrene butadiene, cellulosic resin, and polyacrylic are used. An acid can be used.

  If necessary, a positive electrode active material, a conductive material, and activated carbon are dispersed, and a solvent that dissolves the binder is added to the positive electrode mixture. Specifically, an organic solvent such as N-methyl-2-pyrrolidone can be used as the solvent. Activated carbon can be added to the positive electrode mixture in order to increase the electric double layer capacity.

(3-b) Negative electrode The negative electrode is made of metal lithium, lithium alloy, or the like, or a negative electrode active material capable of occluding and desorbing lithium ions, mixed with a binder, and added with an appropriate solvent to form a paste. The composite material is applied to the surface of a metal foil current collector such as copper, dried, and compressed to increase the electrode density as necessary.

  As the negative electrode active material, for example, organic compound fired bodies such as natural graphite, artificial graphite and phenol resin, and powdery bodies of carbon materials such as coke can be used. In this case, a fluorine-containing resin such as PVDF can be used as the negative electrode binder, as in the case of the positive electrode, and an organic material such as N-methyl-2-pyrrolidone can be used as a solvent for dispersing these active materials and the binder. A solvent can be used.

(3-c) Separator A separator is interposed between the positive electrode and the negative electrode. The separator separates the positive electrode and the negative electrode and retains an electrolyte, and a thin film such as polyethylene or polypropylene and a film having many minute holes can be used.

(3-d) Nonaqueous Electrolytic Solution 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, tetrahydrofuran, 2- 1 type selected from 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, or a mixture of two or more types 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.

  Furthermore, the nonaqueous electrolytic solution may contain a radical scavenger, a surfactant, a flame retardant, and the like.

(3-e) Battery Shape and Configuration The nonaqueous electrolyte secondary battery of the present invention composed of the positive electrode, the negative electrode, the separator, and the nonaqueous electrolytic solution that have been described above includes various types such as a cylindrical shape and a laminated shape. It can be made into a shape. In any case, the positive electrode and the 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 the positive electrode current collector communicates with the outside. A non-aqueous electrolyte secondary battery is completed by connecting between the terminals and between the negative electrode current collector and the negative electrode terminal communicating with the outside using a current collecting lead or the like and sealing the battery case.

(3-f) Characteristics A nonaqueous electrolyte secondary battery using the positive electrode active material of the present invention has a high initial discharge capacity and excellent cycle characteristics. Specifically, when a 2032 type coin battery as shown in FIG. 4 is configured using the positive electrode active material of the present invention, the initial discharge capacity is 160 mAh / g or more, and the capacity maintenance rate after 500 cycles is 85% or more. It can be. Moreover, the nonaqueous electrolyte secondary battery using the positive electrode active material of the present invention has a low positive electrode resistance. For example, in the case where a 2032 type coin battery is configured using the positive electrode active material of the present invention, the positive electrode resistance has an average particle diameter of 3.0 μm to 7.0 μm and [(d90−d10) / MV] of 0.55. The composite hydroxide particles and lithium compound in the following ranges were dry-mixed and calcined at 760 ° C. for 4 hours in the air, then the firing temperature was 860 ° C., the firing time was 10 hours, and the rate of temperature increase was The ratio to the positive electrode resistance (hereinafter referred to as “positive electrode resistance ratio”) when a 2032 type coin battery is configured using the positive electrode active material obtained by firing at 5 ° C./min is 1.00 or less. be able to. Therefore, the non-aqueous electrolyte secondary battery using the positive electrode active material of the present invention is compared with a secondary battery using conventional lithium cobalt composite oxide particles or lithium nickel composite oxide particles as the positive electrode active material. However, it can be said that the thermal stability is high and the safety is also excellent.

  For this reason, the nonaqueous electrolyte secondary battery 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.

  In addition, when a battery for an electric vehicle is increased in size, it is difficult to ensure safety and an expensive protection circuit is indispensable. However, the nonaqueous electrolyte secondary battery of the present invention is excellent without increasing the size of the battery. Since it has safety, not only is it easy to ensure safety, but also an expensive protection circuit can be simplified and the cost can be reduced. Furthermore, since the nonaqueous electrolyte secondary battery of the present invention can be reduced in size and output, it is suitable as a power source for an electric vehicle subject to restrictions on the mounting space. The present invention can be used not only as a power source for an electric vehicle driven purely by electric energy but also as a power source for a so-called hybrid vehicle used in combination with a combustion engine such as a gasoline engine or a diesel engine.

  Examples of the present invention will be specifically described below. The present invention is not limited in any way by these examples. In this example, unless otherwise specified, each reagent manufactured by Wako Pure Chemical Industries, Ltd. was used for the production of the positive electrode active material for a non-aqueous electrolyte secondary battery.

(Example 1)
[Nucleation process]
Pure water was charged to a half amount in a 34 L cylindrical reaction tank (modified stainless steel cylindrical container) equipped with a stirrer and an overflow pipe, and the liquid temperature was kept at 40 ° C. While stirring in this state, nitrogen gas was circulated in the reaction tank, the oxygen concentration in the reaction tank space was 1.0% by volume, and the dissolved oxygen concentration in pure water was 1.5 mg / L. Thereafter, the reaction is carried out by adding an appropriate amount of 25% by mass aqueous sodium hydroxide and 25% by mass ammonia water so that the pH value measured on the basis of the liquid temperature 25 is 12.6 and the ammonium ion concentration is 15 g / L. A pre-aqueous solution was prepared. On the other hand, nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved in pure water so that the molar ratio of metal elements was Ni: Co: Mn = 50: 25: 25 to prepare a mixed aqueous solution.

  To the aqueous solution before the reaction, the mixed aqueous solution was supplied at a rate of 88 ml / min and 25% by mass of ammonia water was supplied at a rate of 8.8 ml / min, and the aqueous solution of 25% by mass of sodium hydroxide was supplied with a pH value of the mixed aqueous solution. It supplied, controlling by a pH controller so that it might be maintained at 12.6 (25 degreeC reference | standard), and the reaction aqueous solution was formed by mixing uniformly. And after adjusting the pH value of this reaction aqueous solution to 12.8 (25 degreeC reference | standard), the pH value was maintained and crystallization was performed for 5 minutes.

[Particle growth process]
After the nucleation step, supply of all aqueous solutions was temporarily stopped, and 70% by mass of sulfuric acid was added until the pH value of the aqueous reaction solution reached 11.6 (25 ° C. reference). After confirming that the pH value of the reaction aqueous solution was 11.6 (25 ° C. standard), the mixed aqueous solution, 25% by mass sodium hydroxide aqueous solution and 25% by mass ammonia were maintained so that this pH value was maintained. Water supply was resumed and crystallization was performed for 2 hours. When the inside of the reaction tank was filled with water, the supply and stirring of all the aqueous solutions were once again suspended and allowed to stand to promote precipitation of the reaction product (complex hydroxide particles). After confirming that the composite hydroxide particles were sufficiently precipitated, a half amount of the supernatant was withdrawn from the reaction vessel, crystallization was resumed, and crystallization was further performed for 2 hours.

[Washing process]
The composite hydroxide particles were filtered from the reaction aqueous solution, transferred to another container, and washed and dehydrated using a rotary filter (RF-1 manufactured by Kotobuki Industries Co., Ltd.). Then, the composite hydroxide slurry whose moisture content is 30 mass% was obtained by adjusting a moisture content.

In addition, after drying a part of the composite hydroxide particles after dehydration, composition analysis was performed by ICP emission spectrometry spectroscopy. As a result, the composition was represented by the general formula: Ni _0.5 Co _0.25 Mn _0.25 (OH) _{2 + α} It was confirmed that it was represented by (0 ≦ α ≦ 0.5). Further, the average particle size (MV), d90 and d10 of the composite hydroxide particles were measured using a laser diffraction scattering type particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., Microtrac HRA). The results are shown in Table 1.

[Mixing process, drying process]
Commercially available lithium carbonate was pulverized using a wet pulverizer (Picomill PCM-L, manufactured by Asada Tekko Co., Ltd.) to obtain a lithium carbonate slurry having an average particle size of 3 μm and a moisture content of 20 mass%.

  Lithium carbonate slurry weighed so as to be Li / Me = 1.10 is added to the composite hydroxide slurry obtained in the water washing step, and shaker mixer apparatus (manufactured by Willy et Bacofen (WAB), TURBULA Type T2C) Was used and wet mixing was performed for 0.2 hours at a rotation speed of 90 rpm to obtain a mixed slurry. This mixed slurry 80 g is irradiated with a high frequency of 1.2 kW for 4 minutes using a high frequency dielectric heating device having a frequency of 4 MHz to 80 MHz, and dried, so that the composite hydroxide particles and lithium carbonate are uniform. A mixed powder was obtained.

[Calcination process, firing process]
This mixed powder was calcined at 760 ° C. for 4 hours in an air (oxygen concentration: 21 vol%) airflow using a firing furnace (manufactured by Advantech Toyo Co., Ltd., electric muffle furnace), and then the firing temperature was 860 ° C. Lithium composite oxide particles were obtained by firing at a firing time of 10 hours and a heating rate of 5 ° C./minute.

[Washing process]
The lithium composite oxide particles were pulverized and then mixed with 1.0 mass of water to make a slurry. The slurry was washed with water, filtered and dried. When the composition analysis was performed on the lithium composite oxide particles after drying by ICP emission spectroscopy, the composition was represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ Was confirmed. Further, the average particle diameter (MV), d90 and d10 of the lithium composite oxide particles were measured using a laser diffraction / scattering particle size distribution analyzer, and [(d90-d10) / MV] and [d90 / MV]. Asked. The results are shown in Table 2. Furthermore, the observation result by SEM (The JEOL Co., Ltd. make, scanning electron microscope JSM-6360LA) is shown in FIG.

[Battery evaluation]
Using the obtained lithium composite oxide particles as a positive electrode active material, a 2032 type coin battery as shown in FIG. 2 was prepared and evaluated by measuring the charge / discharge capacity.

  First, 52.5 mg of a positive electrode active material, 15 mg of acetylene black, and 7.5 mg of polytetrafluoroethylene resin (PTFE) were mixed and press-molded at a pressure of 100 MPa to a diameter of 11 mm and a thickness of 100 μm. Evaluation electrode) (1) was prepared and dried in a vacuum dryer at 120 ° C. for 12 hours.

After drying, using this positive electrode (1), a 2032 type coin battery (B) was produced in a glove box in an Ar atmosphere in which the dew point was controlled at −80 ° C. The negative electrode (2) of the 2032 type coin battery uses lithium metal having a diameter of 17 mm and a thickness of 1 mm, and the electrolytic solution is ethylene carbonate (EC) and diethyl carbonate (DEC) using 1M LiClO ₄ as a supporting electrolyte. The equivalent liquid mixture (made by Toyama Pharmaceutical Co., Ltd.) was used. As the separator (3), a polyethylene porous film having a film thickness of 25 μm was used. The 2032 type coin battery (B) has a gasket (4) and is assembled into a coin-shaped battery by a positive electrode can (5) and a negative electrode can (6).

The produced 2032 type coin battery (B) is left for about 24 hours after assembly, and after the open circuit voltage OCV (Open Circuit Voltage) is stabilized, the current density with respect to the positive electrode is set to 0.1 mA / cm ² and cut off. The battery was charged until the voltage reached 4.3V, and after a pause of 1 hour, a charge / discharge test was performed to measure the discharge capacity when discharged until the cut-off voltage reached 3.0V. A multi-channel voltage / current generator (manufactured by Advantest Corporation, R6741A) was used for the measurement of the charge / discharge capacity. As a result, the initial discharge capacity of the obtained 2032 type coin battery was 171.7 mAh / g.

  Further, as a result of charging the 2032 type coin battery 1 at a charging potential of 4.1 V and performing measurement by an AC impedance method using a frequency response analyzer and a potentiogalvanostat (manufactured by Solartron, 1255B), a Nyquist plot shown in FIG. Obtained. Since this Nyquist plot is represented as the sum of the solution resistance, the negative electrode resistance and its capacity, and the characteristic curve indicating the positive electrode resistance and its capacity, the fitting calculation was performed using an equivalent circuit based on this Nyquist plot, and the positive resistance The value of was calculated. The ratio of the positive electrode resistance value to the positive electrode resistance value (1.60Ω) in Comparative Example 1 described later was defined as the positive electrode resistance ratio. As a result, the positive electrode resistance ratio of Example 1 was 0.75.

Further, assuming that the current density with respect to the positive electrode is ² mA / cm ² , the discharge capacity after repeating 500 cycles of charging to 4.5 V and discharging to 3.0 V is obtained, and the ratio of this discharge capacity to the initial discharge capacity Was defined as the capacity maintenance rate. A multi-channel voltage / current generator (manufactured by Advantest Corporation, R6741A) was used for measuring the charge / discharge capacity. As a result, the capacity retention rate of Example 1 was 93%.

(Example 2)
Lithium composite oxide particles were obtained in the same manner as in Example 1, except that in the drying step, the mixed slurry was dried by irradiation with microwaves having a frequency of 2450 MHz for 8 minutes at an output of 3.0 kW. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Example 2, the average particle size (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Example 3)
In the drying step, lithium composite oxide particles were obtained in the same manner as in Example 1 except that the mixed slurry was dried for 12 hours or more using an air dryer (FORCED CONVECTION OVEN manufactured by Advantech Toyo Co., Ltd.). . The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Example 3, the average particle size (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

Example 4
In the mixing step, lithium composite oxide particles were obtained in the same manner as in Example 1, except that the lithium carbonate slurry weighed so that Li / Me = 1.15 was added to the composite hydroxide slurry. The lithium composite oxide particles were represented by the general formula: Li _1.15 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Example 4, the average particle size (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Example 5)
In the firing step, lithium composite oxide particles were obtained in the same manner as in Example 1 except that the firing temperature was 925 ° C. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Example 5, the average particle diameter (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Example 6)
In the mixing step, the lithium hydroxide slurry weighed so that Li / Me = 1.05 was added to the composite hydroxide slurry, and in the firing step, the firing temperature was set to 925 ° C. Similarly, lithium composite oxide particles were obtained. The lithium composite oxide particles were represented by the general formula: Li _1.05 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Example 6, the average particle size (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Example 7)
In the firing step, lithium composite oxide particles were obtained in the same manner as in Example 1 except that the firing temperature was 950 ° C. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Example 7, the average particle size (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Example 8)
Example 1 except that in the mixing step, lithium carbonate slurry weighed so that Li / Me = 1.05 was added to the composite hydroxide slurry, and in the baking step, the baking temperature was 950 ° C. Similarly, lithium composite oxide particles were obtained. The lithium composite oxide particles were represented by the general formula: Li _1.05 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Example 8, the average particle diameter (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

Example 9
In the nucleation step, lithium composite oxide particles were obtained in the same manner as in Example 3 except that the pH value of the reaction aqueous solution was 12.0. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Example 9, the average particle diameter (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Example 10)
In the particle growth step, lithium composite oxide particles were obtained in the same manner as in Example 3 except that the pH value of the reaction aqueous solution was 11.0. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Example 10, the average particle size (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Example 11)
Lithium composite oxide particles were obtained in the same manner as in Example 1 except that the firing temperature was 800 ° C. in the firing step. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Example 11, the average particle diameter (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Example 12)
In the firing step, lithium composite oxide particles were obtained in the same manner as in Example 1 except that the firing temperature was 1000 ° C. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Example 11, the average particle diameter (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Comparative Example 1)
The composite hydroxide slurry obtained in the water washing step is dried, and lithium carbonate powder weighed so that Li / Me = 1.10 is added thereto, and then a dry pulverization apparatus (manufactured by Tokuju Kogaku Co., Ltd., Julia Mixer) ) Was used to obtain lithium composite oxide particles in the same manner as in Example 1 except that they were mixed. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Comparative Example 1, the average particle size (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Comparative Example 2)
In the firing step, lithium composite oxide particles were obtained in the same manner as in Comparative Example 1 except that the firing temperature was 925 ° C. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Comparative Example 2, the average particle diameter (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Comparative Example 3)
In the nucleation step, lithium composite oxide particles were obtained in the same manner as in Example 3 except that the pH value of the reaction aqueous solution was 11.6. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Comparative Example 3, the average particle diameter (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Comparative Example 4)
In the particle growth step, lithium composite oxide particles were obtained in the same manner as in Example 3 except that the pH value of the reaction aqueous solution was 12.2. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Comparative Example 4, the average particle diameter (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Comparative Example 5)
In the particle growth step, lithium composite oxide particles were obtained in the same manner as in Example 3 except that the pH value of the reaction aqueous solution was 10.8. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Comparative Example 5, the average particle size (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Comparative Example 6)
In the firing step, lithium composite oxide particles were obtained in the same manner as in Example 5 except that the firing temperature was 780 ° C. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Comparative Example 6, the average particle diameter (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Comparative Example 7)
In the firing step, lithium composite oxide particles were obtained in the same manner as in Example 5 except that the firing temperature was 1050 ° C. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Comparative Example 7, the average particle diameter (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Comparative Example 8)
Lithium composite oxide particles were obtained in the same manner as in Example 1 except that the water washing step was not performed after the firing step. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Comparative Example 8, the average particle diameter (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

(Comparative Example 9)
In the particle growth step, lithium composite oxide particles were obtained in the same manner as in Example 1 except that the ammonium ion concentration was 2 g / L. The lithium composite oxide particles were represented by the general formula: Li _1.10 Ni _0.5 Co _0.25 Mn _0.25 O ₂ .

  For each of the composite hydroxide particles and lithium composite oxide particles obtained in Comparative Example 9, the average particle size (MV), [(d90-d10) / MV] and [d90 / MV] was determined. Further, in the same manner as in Example 1, the characteristics (initial discharge capacity, positive electrode resistance ratio, and capacity retention rate) of the nonaqueous electrolyte secondary battery using the lithium composite oxide particles as the positive electrode active material were determined. These results are shown in Tables 1 and 2.

[Evaluation]
From Table 1 and Table 2, in Examples 1-12 which satisfy | fill all the manufacturing conditions of this invention, an average particle diameter exists in the range of 3.0 micrometers-8.0 micrometers, and [(d90-d10) / MV] is 0.00. Since it is 60 or less and [d90 / MV] is 1.300 or less, it is confirmed that a positive electrode active material having an appropriate particle size and an extremely narrow particle size distribution was obtained. Moreover, when a 2032 type coin battery is comprised using this positive electrode active material, it is confirmed that an initial discharge capacity can be 160 mAh / g or more, and the capacity maintenance rate after 500 cycles can be 85% or more. Furthermore, in comparison with Comparative Example 1, it is confirmed that the positive electrode resistance can also be made excellent.

  In contrast, Comparative Examples 1 to 7 are examples in which any of the mixing means, the pH value in the crystallization step, or the firing temperature does not satisfy the conditions of the present invention.

  Comparative Examples 1 and 2 are examples in which mixing in the mixing step was performed using a dry pulverizer. For this reason, in Comparative Examples 1 and 2, the uneven distribution of lithium could not be prevented, and the particle size distribution deviated from the scope of the present invention. As a result, in the 2032 type coin battery using the positive electrode active materials of Comparative Examples 1 and 2, the initial discharge capacity and the capacity retention rate could not be sufficiently improved.

  Comparative Examples 3 to 5 are examples in which the pH value in the nucleation step or the particle growth step is out of the scope of the present invention. In Comparative Example 3, the pH value in the nucleation step was low, the growth of nuclei generated during this step (particle growth) progressed, and the proportion of coarse particles increased, so the particle size distribution deteriorated. In Comparative Example 4, since the pH value in the particle growth process was high, new nuclei were generated during this process, and the proportion of fine particles increased, so the average particle size was reduced and the particle size distribution was also deteriorated. In Comparative Example 5, the pH value in the particle growth process was low, and the metal ions remaining in the reaction aqueous solution increased. Therefore, the particle growth varied and the particle size distribution deteriorated. As a result, in Comparative Examples 3 to 5, the initial discharge capacity and capacity retention rate could not be improved. Further, in Comparative Examples 4 and 5, [d90−d10) / MV] greatly exceeds 0.60, and as a result, the positive electrode resistance is also deteriorated.

  Comparative Examples 6 and 7 are examples in which the firing temperature in the firing step is out of the scope of the present invention. In Comparative Example 6, since the firing temperature was too low, the particle size distribution of the positive electrode active material was included in the scope of the present invention, but the average particle size was slightly small and the crystal structure could not be made uniform. . On the other hand, in Comparative Example 7, since the firing temperature was too high, sintering of the lithium composite oxide particles proceeded, and the particle size distribution deviated from the scope of the present invention. As a result, in Comparative Examples 6 and 7, all of the initial discharge capacity, the positive electrode resistance ratio, and the capacity retention rate are deteriorated.

  Comparative Example 8 is an example in which the water washing step was not performed after the firing step. For this reason, in Comparative Example 8, [(d90−d10) / MV] is 0.60 or less, but [d90 / MV] exceeds 1.300, and the initial discharge capacity and capacity retention rate deteriorate. ing.

  Comparative Example 9 is an example in which the ammonium ion concentration deviates from the scope of the present invention. In Comparative Example 9, since the concentration of ammonium ions was as low as less than 3 g / L, the solubility of metal ions could not be kept constant. As a result, although [d90 / MV] is 1.300 or less, [(d90−d10) / MV] exceeds 0.60, and all of the initial discharge capacity, the positive electrode resistance ratio, and the capacity maintenance ratio are It is getting worse.

1 Positive electrode (Evaluation electrode)
2 Negative electrode 3 Separator 4 Gasket 5 Positive electrode can 6 Negative electrode can B 2032 type coin battery

Claims (14)

General formula (A): Li _{1 + u} Ni _a Co _b Mn _c M _d O ₂ (−0.05 ≦ u ≦ 0.15, a + b + c + d = 1, 0.3 ≦ a ≦ 0.8, 0.1 ≦ b ≦ 0.4, 0.1 ≦ c ≦ 0.4, 0 ≦ d ≦ 0.1, M is selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, W 1 or more elements) and is composed of hexagonal lithium nickel cobalt manganese composite oxide particles having a layered structure, having an average particle size in the range of 3.0 μm to 8.0 μm, and showing a broad particle size distribution An index [[d90-d10) / MV] is 0.60 or less, and [d90 / MV] is 1.300 or less, and a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery,
The crystallization reaction, the general formula _{(B): Ni a Co b} Mn c M d (OH) 2 + α (a + b + c + d = 1,0.3 ≦ a ≦ 0.8,0.1 ≦ b ≦ 0.4, 0.1 ≦ c ≦ 0.4, 0 ≦ d ≦ 0.1, 0 ≦ α ≦ 0.5, M is selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, W [(D90−d10) / MV], which is an index indicating the spread of the particle size distribution, is 0.55. The average particle size is in the range of 3.0 μm to 7.0 μm. A crystallization step to obtain nickel cobalt manganese composite hydroxide particles,
Slurry the nickel-cobalt-manganese composite hydroxide particles, add a lithium compound thereto and wet mix, and a mixing step to obtain a mixed slurry;
Drying the mixed slurry to obtain a mixed powder comprising nickel cobalt manganese composite hydroxide particles and a lithium compound;
Firing the mixed powder in an oxidizing atmosphere at 800 ° C. to 1000 ° C. to obtain lithium nickel cobalt manganese composite oxide particles;
The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries provided with the water washing process which rinses the said lithium nickel cobalt manganese complex oxide particle with water. The crystallization step comprises
A plurality of metal compounds containing nickel, cobalt, and manganese in a pre-reaction aqueous solution adjusted to have a pH value of 12.0 or more measured on the basis of a liquid temperature of 25 ° C. and an ammonium ion concentration of 3 g / L to 25 g / L A nucleation step of forming a reaction aqueous solution by supplying an aqueous solution containing an aqueous solution containing an alkaline solution and an ammonium ion supplier to form a reaction aqueous solution,
After the nucleation step, the supply of the mixed aqueous solution, the aqueous solution containing the alkaline solution and the ammonium ion supplier is stopped, and the pH value measured on the basis of the liquid temperature of 25 ° C. is adjusted to 11.0 to 12.0. Then, while maintaining the pH value at 11.0 to 12.0, the aqueous solution containing the mixed aqueous solution, the alkaline solution and the ammonium ion supplier is supplied again to obtain the nucleation step. A particle growth process for growing the generated nuclei,
The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries of Claim 1 provided with these.   3. The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, further comprising a water washing step of filtering, washing, and dehydrating the nickel cobalt manganese composite hydroxide particles obtained in the crystallization step. Production method.   4. The non-aqueous electrolyte 2 according to claim 3, wherein in the step of washing the nickel cobalt manganese composite hydroxide particles, the nickel cobalt manganese composite hydroxide particles are washed with an apparatus capable of being washed without being fixed on the filter medium. A method for producing a positive electrode active material for a secondary battery.   In the mixing step, the lithium compound is wet pulverized to form a lithium compound slurry, and then wet mixed with the slurry containing the nickel cobalt manganese composite hydroxide particles. A method for producing a positive electrode active material for a water electrolyte secondary battery.   The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 5, wherein lithium carbonate is used as the lithium compound.   The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries of Claim 6 whose average particle diameter of the said lithium carbonate is 10 micrometers or less.   The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 7, wherein in the drying step, the mixed slurry is dried by high-frequency dielectric heating or microwave heating.   The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries in any one of Claims 1-8 which makes oxygen concentration in an oxidizing atmosphere 18 to 100 volume% in the said baking process.   The positive electrode active material for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 9, further comprising a calcining step of calcining the mixed powder at a temperature of 350 ° C to 780 ° C before the calcining step. Manufacturing method.   In the water washing step of the lithium nickel cobalt manganese composite oxide particles, the lithium nickel cobalt manganese composite oxide particles are charged into water having a mass ratio with respect to the lithium nickel cobalt manganese composite oxide particles of 0.5 to 1.0. The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 10, wherein the slurry is washed with water and then the slurry is filtered and dried. Obtained by the production method according to any one of claims 1 to 11, the general formula _{(A): Li 1 + u} Ni a Co b Mn c M d O 2 (-0.05 ≦ u ≦ 0.15, a + b + c + d = 1, 0.3 ≦ a ≦ 0.8, 0.1 ≦ b ≦ 0.4, 0.1 ≦ c ≦ 0.4, 0 ≦ d ≦ 0.1, M is Mg, Ca, Al, 1 or more elements selected from Ti, V, Cr, Zr, Nb, Mo, and W) and is composed of hexagonal lithium nickel cobalt manganese composite oxide particles having a layered structure and an average particle size of 3 [(D90-d10) / MV] is 0.60 or less, and [d90 / MV] is 1.300 or less, which is an index indicating the spread of the particle size distribution in the range of 0.0 μm to 8.0 μm. Positive electrode active material for water electrolyte secondary battery.   A nonaqueous electrolyte secondary comprising a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte, wherein the positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 12 is used as a positive electrode material of the positive electrode. battery. The nonaqueous electrolyte secondary battery according to claim 13, wherein the initial discharge capacity is 160.0 mAh / g or more, the positive electrode resistance ratio is 1.00 or less, and the capacity retention after 500 cycles is 85% or more.