TW201310758A - Method for producing positive electrode active material for lithium ion batteries - Google Patents

Abstract

Provided is a method for efficiently producing a positive electrode active material for lithium ion batteries having good battery characteristics, said positive electrode active material having very small particle diameters with less variation. This method for producing a positive electrode active material for lithium ion batteries comprises: a step wherein a lithium metal nitrate salt solution slurry containing a lithium salt and a metal nitrate salt is prepared; a step wherein a powder of a composite of a lithium metal salt is obtained by spraying and drying the lithium metal nitrate salt solution slurry using a micromist dryer; and a step wherein the powder is fired.

Description

Method for producing positive electrode active material for lithium ion battery

The present invention relates to a method for producing a positive electrode active material for a lithium ion battery.

In recent years, as a high-energy-density battery, the demand for a non-aqueous lithium ion secondary battery has rapidly increased, and research on various viewpoints has been made regarding improvement of performance.

The lithium ion secondary battery is composed of a positive electrode and a negative electrode, and a separator which holds an electrolyte interposed between the electrodes. The positive electrode and the negative electrode are made of an active material, a conductive material, an adhesive, and optionally. A slurry obtained by mixing and dispersing a plasticizer in a dispersion medium is applied to a current collector such as a metal foil or a metal mesh.

As a positive electrode active material, a composite oxide of lithium and a transition metal such as a cobalt-based composite oxide (LiCoO ₂ ), a nickel-based composite oxide (LiNiO ₂ ), or a manganese-based composite oxide (LiMn ₂ O ₄ ) is used. These materials have been proposed as basic materials so far.

The lithium composite oxide used as a positive electrode material for a lithium ion secondary battery is usually a compound (co, such as Co, Ni, and Mn, which is an element of a positive electrode material for a lithium ion secondary battery at a specific ratio). Or an oxide or the like) is mixed with a lithium compound (lithium carbonate or the like) and heat-treated to synthesize it. In the method for synthesizing such a lithium composite oxide, for example, Patent Document 1 discloses a method for producing a precursor material for a positive electrode material for a lithium ion secondary battery, which is characterized in that it is contained in a lithium carbonate suspension. An aqueous solution of one or more kinds of nitrates of Ni, Mn or Co, or a mixed solution of the aqueous solution and an aqueous solution containing one or more kinds of nitrates of Mg, Al, Ti, Cr, Fe, Cu or Zr to contain Li The composite metal carbonate is precipitated, and the obtained Li-containing composite metal carbonate is separated from the solution by solid-liquid separation, and then fired.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-004724

In order to obtain good battery characteristics, in particular, in order to rapidly charge and discharge, it is effective that the positive electrode active material for a lithium ion battery has a small particle diameter and a small particle size unevenness. Therefore, research and development of a method for producing a positive electrode active material for a lithium ion battery having a small particle diameter and a small unevenness are progressing vigorously.

Therefore, an object of the present invention is to provide a method for efficiently producing a positive electrode active material for a lithium ion battery having excellent battery characteristics (rapid charge and discharge characteristics) having a small and uneven particle size.

The present inventors conducted intensive studies and found that a lithium metal nitrate solution slurry containing a lithium salt and a metal nitrate is spray-dried using a micro spray dryer to form a lithium metal salt composite powder, and then fired. In this way, the positive electrode active material for a lithium ion battery having excellent battery characteristics, which has a small and uneven particle diameter, can be efficiently produced.

The present invention, which is based on the above findings, is a method for producing a positive electrode active material for a lithium ion battery, which comprises the steps of preparing a lithium metal nitrate solution slurry containing a lithium salt and a metal nitrate. Step of preparing the above lithium metal nitrate solution slurry using a micro spray dryer a step of performing spray drying to obtain a composite powder of a lithium metal salt; and a step of firing the powder.

In one embodiment of the method for producing a positive electrode active material for a lithium ion battery according to the invention, the metal contained in the metal nitrate is one or more selected from the group consisting of Ni, Mn and Co.

In another embodiment of the method for producing a positive electrode active material for a lithium ion battery according to the present invention, the metal nitrate contains at least Ni, and a molar ratio of Ni in the metal contained in the powder is 0.3 or more.

In still another embodiment of the method for producing a positive electrode active material for a lithium ion battery according to the present invention, the metal nitrate contains at least Ni and Mn, and a molar ratio of Ni in the metal contained in the powder is larger than a molar ratio of Mn.

In still another embodiment of the method for producing a positive electrode active material for a lithium ion battery of the present invention, the lithium salt is lithium carbonate.

According to the manufacturing method of the present invention, by spraying a lithium metal nitrate solution slurry by using a micro spray dryer, the particle size distribution of the particles can be made precise, the particle size unevenness can be well controlled, and the general The dry powder having a particle diameter of 20 to 30 μm at the time of drying forms a minute particle diameter of several μm. Therefore, various characteristics of the lithium ion battery using the positive electrode active material for a lithium ion battery produced by the production method of the present invention are excellent. Further, drying and fine particle formation can be simultaneously performed, and the production efficiency is improved.

(Composition of positive active material for lithium ion battery)

The material of the positive electrode active material for a lithium ion battery to be produced in the production method of the present invention can be widely used as a compound which is useful as a positive electrode active material for a positive electrode for a general lithium ion battery, and in particular, lithium cobaltate (LiCoO _{2 )} is used. A lithium-containing transition metal oxide such as lithium nickelate (LiNiO ₂ ) or lithium manganate (LiMn ₂ O ₄ ) is preferred. The positive electrode active material for a lithium ion battery fabricated using the above materials is of a composition formula: Li _x Ni _1-y M _y O ₂

(In the above formula, M is one or more selected from the group consisting of Ni, Mn, and Co, and 0.9 ≦ x ≦ 1.1, 0 < y ≦ 0.7).

The ratio of lithium to the total metal in the positive electrode active material for a lithium ion battery is 0.9 to 1.1 because it is difficult to maintain a stable crystal structure when it is less than 0.9, and when it exceeds 1.1, the capacity is lowered.

The positive electrode active material for a lithium ion battery produced by the production method of the present invention contains an aggregate of primary particles, and the average particle diameter of the primary particles is 1.0 to 3.0 μm.

Considering the moving distance of lithium ions during charge and discharge, although the average particle diameter of the primary particles is smaller, the conduction distance is shorter, which is advantageous for rapid charge and discharge, but if the average particle diameter is small, the electrode is fabricated. The possibility of particle damage when the electrode is pressurized becomes high. Therefore, the average particle diameter of the primary particles exists in an appropriate range, and is preferably 1.0 to 3.0 μm. When the average particle diameter is less than 1.0 μm, there is a possibility that the primary particles are destroyed in the pressurization treatment at the time of electrode production. In addition, when the average particle diameter exceeds 3.0 μm, the moving distance of lithium ions during charge and discharge becomes long, and it becomes difficult to charge and discharge rapidly.

Further, the average particle diameter of the secondary particles formed by agglomerating the primary particles is preferably 5.0 to 9.0 μm. When the average particle diameter of the secondary particles is less than 5.0 μm, When the slurry is applied, a large amount of solvent is required, which is not preferable in terms of industrial production. In addition, when the average particle diameter of the secondary particles exceeds 9.0 μm, the contact area with the electrolytic solution becomes small, and it becomes difficult to rapidly charge and discharge.

In addition, when the particle size distribution curve is expressed by a general particle size distribution meter and the particle size distribution curve of the frequency is used as the center of the average particle diameter, it is considered that the unevenness is the least in the left-right symmetry, and the following conditions are used as the index of unevenness. .

That is, when the maximum diameter (μm) is expressed as dmax, the average diameter (μm) is expressed as d50, and the minimum diameter (μm) is expressed as dmin, if the ratio (dmax/d50) is the common logarithm and (d50/ The common logarithm of the ratio of dmin) is less than 0.7, and the particle size of the above unevenness is small. If the condition is expressed by the formula, it is as follows: Log (maximum diameter (μm) / average particle diameter (μm)) <0.70

Log (average particle size (μm) / minimum diameter (μm)) <0.70

(Method for producing positive electrode active material for lithium ion battery)

A method for producing a positive electrode active material for a lithium ion battery according to an embodiment of the present invention will be described in detail.

First, a metal nitrate containing one or more metals selected from the group consisting of Ni, Mn, and Co is prepared. As the metal nitrate, for example, nickel nitrate, cobalt nitrate, manganese nitrate or the like can be used. When the nitrate is used as described above, it can be directly fired even if it is mixed into the calcined raw material in the form of impurities, so that the washing step can be omitted, and the nitrate functions as an oxidizing agent, and the raw material is promoted. The role of the oxidation of metals. Further, the respective metals contained in the metal nitrate are adjusted to have a desired molar ratio. Thereby, the molar ratio of each metal in the positive electrode active material is determined. In the case of containing Ni in a metal nitrate solution In the case of the metal, the molar ratio of Ni in the metal is preferably 0.3 or more. The reason for this is that when the molar ratio of Ni is less than 0.3, the absolute amount of oxygen required for firing a 1 mol of the positive electrode material is reduced. Further, when the metal nitrate solution contains at least Ni and Mn, the molar ratio of Ni in the metal contained is preferably larger than the molar ratio of Mn. The reason for this is that when the molar ratio of Ni is equal to or less than the molar ratio of Mn, the valence of Ni becomes divalent, and it is not necessary to oxidize Ni during the heat treatment.

Then, the lithium source is suspended in pure water, for example, and then the metal salt solution of the above metal is introduced to adjust the lithium metal nitrate solution slurry.

Then, the lithium metal nitrate solution slurry was spray-dried by a micro spray dryer to obtain a lithium metal salt composite powder. When the metal of the metal salt is expressed as "M", the reaction at this time is represented by the following chemical formulas. This step will be described below. It is known that, in general, a metal nitrate loses nitric acid due to heating to become an alkaline salt, and the reaction is carried out while drying.

M(NO ₃ ) ₂ +1/2Li ₂ CO ₃ → 1/2MCO ₃ +1/2M(NO ₃ ) ₂ +LiNO ₃ (1)

M(NO ₃ ) ₂ +1/2Li ₂ CO ₃ +5/6H ₂ O → 1/3M ₃ (NO ₃ ) ₂ (OH) ₄ +LiNO ₃ +1/3HNO ₃ +1/2CO ₂ (2)

M(NO ₃ ) ₂ +1/2Li ₂ CO ₃ +H ₂ O+1/4O ₂ → MOOH+LiNO ₃ +HNO ₃ +1/2CO ₂ (3)

M(NO ₃ ) ₂ +1/2Li ₂ CO ₃ +3/2H ₂ O → 1/2(M(NO ₃ ) ₂ (OH) ₂ .2H ₂ O)+LiNO ₃ +1/2CO ₂ (4)

The micro spray dryer uses a spray dryer of a micronizing device, and the lithium metal salt solution slurry is extended thinly under a plurality of paths by a high-speed air flow, and the shock wave is caused by the collision with the specific collision focus. Thereby, a spray of several μm can be formed. The micronizing device is preferably, for example, a four-fluid nozzle. The micronization device with four-fluid nozzles makes the nozzle edges symmetrical and provides two paths of liquid and gas, for example, by atomizing the fluid flow surface and the collision focus at the front end of the edge.

The resulting spray is dried in a drying chamber in a micro spray dryer to produce a dry powder of a composite of lithium metal nitrate having a small particle diameter (several μm) mainly composed of a compound on the right side of the above formula.

Thus, by using a micro spray dryer, at least the following effects are obtained:

(1) A single micron droplet can be sprayed in a large amount.

(2) The average droplet diameter can be controlled by changing the gas-liquid ratio.

(3) The particle size distribution of the particles becomes precise, so that the unevenness of the particle diameter is favorably suppressed.

(4) The nozzle clogging generated by the external mixing method is suppressed, and the spray can be continuously performed for a long time.

(5) The necessary amount of spray can be easily obtained by adjusting the length of the edge.

(6) The dry powder having a particle diameter of 20 to 30 μm can be formed into a minute particle diameter of several μm during general drying.

(7) Simultaneous drying and micro-particle formation for improved manufacturing efficiency it is good.

Then, the dry powder is filled in a firing container of a specific size so as to have a specific thickness, and is subjected to oxidation treatment and pulverization for heating for a specific period of time at atmospheric pressure in an environment capable of maintaining oxidation in the atmosphere or the like. A powder of a positive electrode active material is obtained. When the metal of the metal salt is represented by "M", the reaction at this time is represented by the following chemical formula. In either formula, the oxygen term is present on the right side, indicating that oxygen is generated from the calcined feedstock.

1/2MCO ₃ +1/2M(NO ₃ ) ₂ +LiNO ₃ → LiMO ₂ +2NO ₂ +1/2CO ₂ +1/4O ₂ (5)

1/3M ₃ (NO ₃ ) ₂ (OH) ₄ +LiNO ₃ → LiMO ₂ +5/3NO ₂ +2/3H ₂ O+1/6O ₂ (6)

MOOH+LiNO ₃ → LiMO ₂ +NO ₂ +1/2H ₂ O+1/4O ₂ (7)

1/2(M ₂ (NO ₃ ) ₂ (OH) ₂ .2H ₂ O)+LiNO ₃ → LiMO ₂ +2NO ₂ +3/2H ₂ O+1/4O ₂ (8)

The oxidation treatment can be carried out in a continuous furnace or other furnaces, in addition to the usual static furnace.

Thus, in the present invention, the lithium metal nitrate solution slurry is spray-dried using a micro spray dryer, whereby the particle size distribution of the particles becomes precise, so that the particle size unevenness can be satisfactorily suppressed, and the drying can be generally performed. The dry powder having a particle diameter of 20 to 30 μm was formed into a minute particle diameter of several μm. Therefore, various characteristics of the lithium ion battery using the positive electrode active material for a lithium ion battery manufactured by the production method of the present invention are excellent. Further, drying and fine particle formation can be simultaneously performed, and the production efficiency is improved.

[Examples]

The following examples are provided to better understand the present invention and its advantages, but the invention is not limited to the embodiments.

(Example 1)

First, after 517 g of lithium carbonate was suspended in 1.06 liter of pure water, a 4.8 liter metal salt solution was charged. Here, the metal salt solution adjusts each hydrate of nickel nitrate, cobalt nitrate, and manganese nitrate so that Ni, Mn, and Co become a specific ratio, and the total number of moles of Ni, Mn, and Co becomes 14 moles. The way to adjust.

In addition, the suspension amount of lithium carbonate is calculated by the following formula when the chemical formula of the product is represented by Li _x Ni _1-y M _y O ₂ as x=1.0.

W (g) = molecular weight of lithium carbonate × (total number of Ni, Mn, Co) × 0.5 = 73.9 × 14 × 0.5 = 517

The _ratio of the "0.5" product (Li _x Ni _1-y M _y O ₂ ) in the formula to the Li content of lithium carbonate (Li ₂ CO ₃ ).

Further, the ratio of Ni, Mn, and Co was adjusted so that Ni:Mn:Co=1:1:1. This is equivalent to y = 0.66 when the chemical formula of the product is represented by Li _x Ni _1-y M _y O ₂ , and M is obtained by adjusting Mn and Co at the same ratio.

A slurry is formed by introducing a metal nitrate solution into the lithium carbonate suspension prepared in this manner.

Then, the slurry was spray-dried using a micro spray dryer (MDL-100M) manufactured by Fujisaki Electric Co., Ltd. to obtain 2800 g of a dry powder of a lithium metal nitrate composite (precursor material for a lithium ion secondary battery positive electrode material) material).

According to the XRD diffraction of the composite, it was confirmed that the composite system was formed of lithium nitrate (LiNO ₃ ) and basic metal nitrate {M ₃ (NO ₃ ) ₂ (OH) ₄ : M as a metal component}.

Then, a firing container having a length × width = 280 mm × 280 mm and a container height of 100 mm was prepared, and the resulting composite was filled in the firing container so that the height of the composite was 55 mm. The mixture was oxidized at 980 ° C for 12 hours in an air atmosphere. The obtained oxide was crushed in a ball mill to obtain a powder of a lithium ion secondary battery positive electrode material.

(Comparative Example 1)

In the same manner as in Example 1, a metal nitrate solution was poured into a lithium carbonate suspension to prepare a slurry, and the slurry was dried by a hot air circulation type dryer (BCL-20 type) manufactured by Asahi Scientific Co., Ltd., and obtained. A dry powder of a composite of 2800 g of lithium metal nitrate (precursor material for a positive electrode material for a lithium ion secondary battery).

After drying, it was sized by using a 25 μm sieve to form a raw material for firing.

Then, a firing container having a length × width = 280 mm × 280 mm and a container height of 100 mm was prepared, and the resulting composite was filled in the firing container so that the height of the composite was 55 mm. The mixture was oxidized at a temperature of 980 ° C for 12 hours in an air atmosphere. The obtained oxide was crushed in a ball mill to obtain a powder of a lithium ion secondary battery positive electrode material.

(Example 2)

First, after 517 g of lithium carbonate was suspended in 1.06 liter of pure water, a 4.8 liter metal salt solution was charged. Here, the metal salt solution adjusts each hydrate of nickel nitrate, cobalt nitrate, and manganese nitrate so that Ni, Mn, and Co become a specific ratio, and the total number of moles of Ni, Mn, and Co becomes 14 moles. The way to adjust.

In addition, the suspension amount of lithium carbonate is calculated by the following formula when the chemical formula of the product is represented by Li _x Ni _1-y M _y O ₂ as x=1.0.

W (g) = molecular weight of lithium carbonate × (total number of Ni, Mn, Co) × 0.5 = 73.9 × 14 × 0.5 = 517

The _ratio of the "0.5" product (Li _x Ni _1-y M _y O ₂ ) in the formula to the Li content of lithium carbonate (Li ₂ CO ₃ ).

Further, the ratio of Ni, Mn, and Co was adjusted so that Ni:Mn:Co=0.6:0.25:0.15. This is equivalent to y=0.4 when the chemical formula of the product is represented by Li _x Ni _1-y M _y O ₂ , and M is obtained by adjusting Mn and Co with Mn:Co=0.625:0.375.

The slurry is formed by introducing a metal nitrate solution into the lithium carbonate suspension prepared in this manner.

Then, the slurry was spray-dried using a micro spray dryer (MDL-100M) manufactured by Fujisawa Electric Co., Ltd. to obtain a dry powder of a composite of 2800 g of lithium metal nitrate (precursor material for a lithium ion secondary battery positive electrode material).

According to the XRD diffraction of the composite, it was confirmed that the composite system was formed of lithium nitrate (LiNO ₃ ) and basic metal nitrate {M ₃ (NO ₃ ) ₂ (OH) ₄ : M as a metal component}.

Then, a firing container having a length × width = 280 mm × 280 mm and a container height of 100 mm was prepared, and the resulting composite was filled in the firing container so that the height of the composite was 55 mm. The mixture was oxidized at a temperature of 870 ° C for 12 hours in an air atmosphere. The obtained oxide was crushed in a ball mill to obtain a powder of a lithium ion secondary battery positive electrode material.

(Comparative Example 2)

In the same manner as in Example 2, a metal nitrate solution was poured into a lithium carbonate suspension to prepare a slurry, and the slurry was dried by a hot air circulation type dryer (BCL-20 type) manufactured by Asahi Scientific Co., Ltd., and obtained. A dry powder of a composite of 2800 g of lithium metal nitrate (precursor material for a positive electrode material for a lithium ion secondary battery).

After drying, it was sized by using a 25 μm sieve to form a raw material for firing.

Then, a firing container having a length × width = 280 mm × 280 mm and a container height of 100 mm was prepared, and the resulting composite was filled in the firing container so that the height of the composite was 55 mm. The mixture was oxidized at a temperature of 870 ° C for 12 hours in an air atmosphere. The obtained oxide was crushed in a ball mill to obtain a powder of a lithium ion secondary battery positive electrode material.

(Example 3)

First, after 517 g of lithium carbonate was suspended in 1.06 liter of pure water, a 4.8 liter metal salt solution was charged. Here, the metal salt solution is Ni, Each of the hydrates of nickel nitrate, cobalt nitrate, and manganese nitrate was adjusted so that Mn and Co became a specific ratio, and the total number of moles of Ni, Mn, and Co was adjusted to be 14 moles.

In addition, the suspension amount of lithium carbonate is calculated by the following formula when the chemical formula of the product is represented by Li _x Ni _1-y M _y O ₂ as x=1.0.

W (g) = molecular weight of lithium carbonate × (total number of Ni, Mn, Co) × 0.5 = 73.9 × 14 × 0.5 = 517

The _ratio of the "0.5" product (Li _x Ni _1-y M _y O ₂ ) in the formula to the Li content of lithium carbonate (Li ₂ CO ₃ ).

Further, the ratio of Ni, Mn, and Co was adjusted so that Ni:Mn:Co=0.8:0.1:0.1. This is equivalent to y=0.2 when the chemical formula of the product is represented by Li _x Ni _1-y M _y O ₂ , and M is obtained by adjusting Mn and Co at the same ratio.

The slurry is formed by introducing a metal nitrate solution into the lithium carbonate suspension prepared in this manner.

Then, the slurry was spray-dried using a micro spray dryer (MDL-100M) manufactured by Fujisawa Electric Co., Ltd. to obtain a dry powder of a composite of 2800 g of lithium metal nitrate (precursor material for a lithium ion secondary battery positive electrode material).

According to the XRD diffraction of the composite, it was confirmed that the composite system was formed of lithium nitrate (LiNO ₃ ) and basic metal nitrate {M ₃ (NO ₃ ) ₂ (OH) ₄ : M as a metal component}.

Then, a firing container having a length × width = 280 mm × 280 mm and a container height = 100 mm is prepared, and the height of the composite is The resulting composite was filled in the firing vessel in a 55 mm manner and oxidized at a temperature of 820 ° C for 12 hours in an air atmosphere. The obtained oxide was crushed in a ball mill to obtain a powder of a lithium ion secondary battery positive electrode material.

(Comparative Example 3)

In the same manner as in Example 3, a metal nitrate solution was poured into a lithium carbonate suspension to prepare a slurry, and the slurry was dried by a hot air circulation type dryer (BCL-20 type) manufactured by Asahi Scientific Co., Ltd., and obtained. A dry powder of a composite of 2800 g of lithium metal nitrate (precursor material for a positive electrode material for a lithium ion secondary battery).

After drying, it was sized by using a 25 μm sieve to form a raw material for firing.

Then, a firing container having a length × width = 280 mm × 280 mm and a container height of 100 mm was prepared, and the resulting composite was filled in the firing container so that the height of the composite was 55 mm. The mixture was oxidized at a temperature of 820 ° C for 12 hours in an air atmosphere. The obtained oxide was crushed in a ball mill to obtain a powder of a lithium ion secondary battery positive electrode material.

(Evaluation)

With respect to Examples 1 to 3 and Comparative Examples 1 to 3, the contents of Li, Ni, Mn, and Co were measured by the ICP method, and the results shown in Table 1 were obtained.

The size of the primary particles of the positive electrode material was measured by the measurement software attached to the SEM observation apparatus, and the results shown in Table 1 were obtained.

The average particle size of the secondary particles of the positive electrode material powder is manufactured by Nikkiso Microtrak MT3300EX II was measured. The minimum diameter, the maximum diameter, and the average diameter (D50) of the positive electrode material were obtained from the measurement results, and the ratio of the maximum diameter/average diameter to the average diameter/minimum diameter was calculated, and the common logarithmic value was calculated to obtain the table 1 shown in Table 1. result.

The electrode for battery characteristics evaluation is kneaded in NMP (N-methylpyrrolidone) as an organic solvent in the ratio of active material: binder: conductive material = 85:8:7, and kneaded The resultant was applied to an Al foil and dried after pressing to prepare.

Using these, a 2032 type coin cell in which the counter electrode was evaluated for Li was produced, and 1 M of LiPF ₆ was used as the electrolyte solution, and the electrolyte was used to dissolve the ethyl carbonate in a volume ratio of 1:1. (EC) and dimethyl carbonate (DMC) are charged and discharged as follows: charging is performed in a constant current constant voltage mode with a voltage of 4.3 V, and discharging is performed in a constant current mode. It is set to 3.0V. The initial capacity and initial efficiency (discharge amount/charge amount) were confirmed by charge and discharge at 0.1 C. The ratio characteristics were evaluated by the ratio of the discharge capacity at 2 C to the discharge capacity at 0.1 C.

The evaluation results are shown in Table 1.

In Examples 1 to 3, the primary particles were both large and the secondary particles were small, and the unevenness of the particle diameter, particularly the variation of the minimum diameter and the maximum diameter, was favorably suppressed, indicating that it was suitable for rapid charge and discharge. Particle size distribution. Both the discharge capacity and the ratio characteristics are good.

In Comparative Examples 1 to 3, the primary particles became smaller in distribution and the secondary particles became larger in distribution, and the unevenness in particle diameter was large, and the discharge capacity and the ratio characteristics were both poor results.

Claims (5)

A method for producing a positive electrode active material for a lithium ion battery, comprising the steps of: preparing a lithium metal nitrate solution slurry containing a lithium salt and a metal nitrate; and using the micro spray dryer to dissolve the lithium metal nitrate solution slurry a step of performing spray drying to obtain a composite powder of a lithium metal salt; and a step of firing the powder. The method for producing a positive electrode active material for a lithium ion battery according to the first aspect of the invention, wherein the metal contained in the metal nitrate is one or more selected from the group consisting of Ni, Mn and Co. The method for producing a positive electrode active material for a lithium ion battery according to claim 1 or 2, wherein the metal nitrate contains at least Ni, and a molar ratio of Ni in the metal contained in the powder is 0.3 or more. The method for producing a positive electrode active material for a lithium ion battery according to claim 1 or 2, wherein the metal nitrate contains at least Ni and Mn, and a molar ratio of Ni in the metal contained in the powder is greater than that of Mn. Ear ratio. The method for producing a positive electrode active material for a lithium ion battery according to claim 1 or 2, wherein the lithium salt is lithium carbonate.