JP2023142148A - Positive electrode active material for lithium secondary battery, positive electrode for lithium secondary battery, lithium secondary battery, and method for producing positive electrode active material for lithium secondary battery - Google Patents

Abstract

To provide a positive electrode active material for a lithium secondary battery which does not easily crack even when repeatedly charged and discharged, and can improve cycle maintenance rate and discharge rate characteristics, and a method for manufacturing the same.SOLUTION: A positive electrode active material for a lithium secondary battery includes lithium metal composite oxide particles having pores and containing Li and element M, and a compound containing Si located in the pore, and the ratio of the amount of Si to the sum of the amounts of the elements M and Si is greater than 0 mol% and less than or equal to 5.0 mol%, and the ratio of B50, B50/A50 which is a ratio of 50% cumulative volume particle size of a positive electrode active material for a lithium secondary battery after powder compaction treatment at 35 MPa with respect to 50% cumulative volume particle size A50 of the positive electrode active material for the lithium secondary battery before powder compaction treatment is 0.92 to 1.00.SELECTED DRAWING: None

Description

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

Lithium metal composite oxide is used as a positive electrode active material for lithium secondary batteries. When a lithium secondary battery is charged and discharged, lithium ions are desorbed from the positive electrode active material for a lithium secondary battery and lithium ions are inserted into the positive electrode active material for a lithium secondary battery. When a lithium secondary battery is repeatedly charged and discharged, the positive electrode active material for a lithium secondary battery repeatedly expands and contracts, and cracks may occur in the positive electrode active material for a lithium secondary battery. Since this cracking reduces the cycle maintenance rate of lithium secondary batteries, attempts have been made to control the strength of positive electrode active materials for lithium secondary batteries.

Patent Document 1 discloses a lithium composite oxide consisting of monodisperse primary particles containing Li and one element selected from the group of Co, Ni, and Mn as main components. The lithium composite oxide described in Patent Document 1 has a specific average particle diameter, specific surface area, and bulk density, and has no grain boundaries. Therefore, it has the characteristic that cracks in the positive electrode active material, which are caused by pressing of the positive electrode active material during positive electrode molding and expansion and contraction of the positive electrode active material during charging and discharging of a lithium secondary battery, are less likely to occur.

JP-A-2004-355824

As described in Patent Document 1, a lithium composite oxide consisting of monodisperse primary particles is difficult to crack or break, but from the viewpoint of improving both the discharge rate characteristics and cycle maintenance rate of a lithium secondary battery, There is room for further improvement.

The present invention has been made in view of the above circumstances, and is designed to prevent cracks from occurring in the positive electrode active material for a lithium secondary battery even if the lithium secondary battery is repeatedly charged and discharged, thereby improving the cycle maintenance rate and discharge of the secondary battery. Provides a positive electrode active material for lithium secondary batteries that can improve rate characteristics, a positive electrode for lithium secondary batteries using the same, a lithium secondary battery using the same, and a method for producing a positive electrode active material for lithium secondary batteries. The purpose is to

The present invention has the following aspects.
[1] A positive electrode active material for a lithium secondary battery comprising particles of a lithium metal composite oxide having pores and containing Li and element M, and a compound containing Si and located in the pores. The ratio of the amount of Si to the total amount of the elements M and Si is greater than 0 mol% and 5.0 mol% or less, B ₅₀ /A ₅₀ , which is the ratio of 50% cumulative volume particle size B ₅₀ of the positive electrode active material for lithium secondary battery after compaction treatment at 35 MPa to % cumulative volume particle size A ₅₀ , is 0.92-1.00. A positive electrode active material for lithium secondary batteries.
[2] _The 10% cumulative volume particle size B of the positive electrode active material for a lithium secondary battery after the powder compaction process relative to the 10% cumulative volume particle size A ₁₀ of the positive electrode active material for a lithium secondary battery before the powder compaction process The positive electrode active material for a lithium secondary battery according to [1], wherein the ratio B ₁₀ /A ₁₀ is 0.92-1.00.
[3] The 90% cumulative volume particle size B of the positive electrode active material for lithium secondary batteries after the powder compacting process is ₉₀ relative to the 90% cumulative volume particle size A ₉₀ of the positive electrode active material for a lithium secondary battery before the compacting process. The positive electrode active material for a lithium secondary battery according to [1] or [2], wherein the ratio B ₉₀ /A ₉₀ is 0.94-1.00.
[4] The lithium metal composite oxide contains Ni and element X as the element M, and the element X is Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn. , Zr, Ga, B, S, and P, and the material amount ratio of Li, the Ni, and the element X contained in the positive electrode active material for lithium secondary batteries. is the positive electrode active material for a lithium secondary battery according to any one of [1] to [3], which satisfies the following formula (I).
[Li]:[Ni]:[X]=b:(1-a):a (I)
(However, 0.9≦b≦1.2 and 0<a≦0.2)
[5] The positive electrode active material for a lithium secondary battery according to any one of [1] to [4], wherein the positive electrode active material for a lithium secondary battery has a BET specific surface area of 2.0 m ² /g or less. .
[6] A positive electrode for a lithium secondary battery, comprising the positive electrode active material for a lithium secondary battery according to any one of [1] to [5].
[7] A lithium secondary battery having the positive electrode for a lithium secondary battery according to [6].
[8] A step of mixing a metal composite compound containing element M and a solution containing Si to obtain a mixture, a step of drying the mixture to obtain a Si-containing metal composite compound, and a step of mixing the Si-containing metal composite compound and lithium. A method for producing a positive electrode active material for a lithium secondary battery, comprising a step of mixing and firing a compound.
[9] In the step of obtaining the mixture, the metal composite compound and the Si are mixed so that the ratio of the amount of Si to the total amount of the elements M and Si is greater than 0 mol% and less than or equal to 5.0 mol%. The method for producing a positive electrode active material for a lithium secondary battery according to [8], which comprises mixing the positive electrode active material with a solution containing the lithium secondary battery.
[10] The positive electrode active material for a lithium secondary battery includes Li and a lithium metal composite oxide containing Ni and element X as the element M, where the element X is Co, Mn, Fe, Cu, Ti, Li is at least one element selected from the group consisting of Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, B, S, and P, and is contained in the positive electrode active material for lithium secondary batteries. The method for producing a positive electrode active material for a lithium secondary battery according to [8] or [9], wherein the material ratio of the Ni, and the element X satisfies the following formula (I).
[Li]:[Ni]:[X]=b:(1-a):a (I)
(However, 0.9≦b≦1.2 and 0<a≦0.2)

According to the present invention, even if a lithium secondary battery is repeatedly charged and discharged, cracks do not easily occur in the positive electrode active material for a lithium secondary battery, and the lithium lithium battery can improve the cycle retention rate and discharge rate characteristics of the secondary battery. It is possible to provide a positive electrode active material for a secondary battery, a positive electrode for a lithium secondary battery using the same, a lithium secondary battery using the same, and a method for producing a positive electrode active material for a lithium secondary battery.

1 is an SEM cross-sectional image of a positive electrode active material for a lithium secondary battery in one aspect of the present embodiment. It is an image in which a mapping image of Si element is superimposed on a SEM cross-sectional image of a positive electrode active material for a lithium secondary battery in one aspect of the present embodiment. FIG. 1 is a schematic cross-sectional view of a powder processing apparatus in one aspect of the present embodiment. FIG. 1 is a schematic configuration diagram showing an example of a lithium secondary battery in one aspect of the present embodiment. FIG. 1 is a schematic diagram showing the overall configuration of an all-solid-state lithium secondary battery in one aspect of the present embodiment.

Hereinafter, a positive electrode active material for a lithium secondary battery in one embodiment of the present invention will be described. In the following embodiments, preferred examples and conditions may be shared. Moreover, in this specification, each term is defined below.

In the present specification, a metal composite compound (Metal Composite Compound) is hereinafter referred to as "MCC", a lithium metal composite oxide (Lithium Metal composite Oxide) is hereinafter referred to as "LiMO", and a positive electrode active material for lithium secondary batteries (Cathode Active Material for lithium secondary batteries) is hereinafter referred to as "CAM".

"Ni" refers to a nickel atom, not nickel metal. Similarly, "Co" and "Li" etc. refer to a cobalt atom, a lithium atom, etc., respectively.

For example, when a numerical range is described as "1-10 μm" or "1-10 μm", it means a range from 1 μm to 10 μm, and a numerical range including a lower limit of 1 μm and an upper limit of 10 μm.

[BET specific surface area]
The BET specific surface area is a value measured by the BET (Brunauer, Emmett, Teller) method. In the measurement of the BET specific surface area, nitrogen gas is used as the adsorption gas. For example, after drying 1 g of powder to be measured at 150°C for 30 minutes in a nitrogen atmosphere, measurement can be performed using a BET specific surface area meter (for example, Macsorb (registered trademark) manufactured by Mountech) (unit: m ² /g).

[Cumulative volume particle size]
Cumulative volume particle size is a value measured by laser diffraction scattering method. Specifically, 0.1 g of a powder to be measured, for example, CAM, is added to 50 ml of a 0.2% by mass sodium hexametaphosphate aqueous solution to obtain a dispersion in which the powder is dispersed. Next, the particle size distribution of the obtained dispersion liquid is measured using a laser diffraction scattering particle size distribution measuring device (for example, Microtrac MT3300EXII manufactured by Microtrac Bell Co., Ltd.) to obtain a volume-based cumulative particle size distribution curve. . In the obtained cumulative particle size distribution curve, the particle diameter value when 10% cumulative from the microparticle side is the 10% cumulative volume particle size (μm), and the particle diameter value when 50% cumulative from the microparticle side is the 50% cumulative volume. Particle size: The value of the particle size when 90% cumulative from the fine particle side is the 90% cumulative volume particle size.

[Composition analysis]
The composition of CAM is measured using an ICP emission spectrometer after each powder is dissolved in acid or alkali depending on the element to be measured. As the ICP emission spectrometer, for example, Optima 7300 (manufactured by PerkinElmer Co., Ltd.) can be used.

"Cycle maintenance rate" refers to the initial discharge capacity of a lithium secondary battery after a cycle test in which the lithium secondary battery is charged and discharged a predetermined number of times under specific conditions. It means the percentage of discharge capacity of a lithium secondary battery.
In this specification, "cycle maintenance rate" is measured under the conditions shown below.

[Cycle test]
After the above-mentioned initial charging/discharging test, one cycle is charging/discharging under the following conditions, and a test is performed in which this cycle is repeated 50 times.
Test temperature: 25℃
Maximum charging voltage 4.3V, charging current 0.5CA, constant current constant voltage charging, ends at 0.05CA current value Minimum discharge voltage 2.5V, discharge current 1CA, constant current discharge

The value obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the 1st cycle is calculated, and this value is taken as the cycle maintenance rate (%).

"Discharge rate characteristic" refers to the ratio of discharge capacity at 3CA when discharge capacity at 0.2CA is taken as 100%. The higher this ratio, the higher the output of the battery, which is preferable in terms of battery performance. In this specification, the value obtained by conducting a discharge rate test under the following conditions is used as an index of discharge rate characteristics.

[Discharge rate test]
Test temperature: 25℃
Maximum charge voltage 4.3V, charging current 0.2CA, constant current constant voltage charging Minimum discharge voltage 2.5V, discharge current 0.2CA or 3CA, constant current discharge

Using the discharge capacity when discharging at a constant current of 0.2CA and the discharge capacity when discharging at a constant current of 3CA, calculate the 3CA/0.2CA discharge capacity ratio obtained by the following formula, and calculate the discharge rate characteristic. Use it as an indicator.
(3CA/0.2CA discharge capacity ratio)
3CA/0.2CA discharge capacity ratio (%)
=Discharge capacity at 3CA/Discharge capacity at 0.2CA×100

<Cathode active material for lithium secondary batteries>
The CAM of this embodiment is a positive electrode for a lithium secondary battery, which has pores and includes particles of a lithium metal composite oxide containing Li and element M, and a compound located in the pores and containing Si. The positive electrode for a lithium secondary battery is an active material, and the ratio of the amount of Si to the total amount of the elements M and Si is greater than 0 mol% and not more than 5.0 mol%, and the positive electrode for a lithium secondary battery is not subjected to powder compaction treatment. B ₅₀ /A ₅₀ , which is the ratio of the 50% cumulative volume particle size B ₅₀ of the positive electrode active material for lithium secondary batteries after the powder compaction treatment at 35 MPa to the 50% cumulative volume particle size A ₅₀ of the active material, is 0.92- It is 1.00.

The CAM in this embodiment is an aggregate of a plurality of particles. In other words, the CAM in this embodiment is in powder form. In this embodiment, the aggregate of a plurality of particles may include only secondary particles, or may be a mixture of primary particles and secondary particles.

In the present embodiment, "primary particles" refer to particles that do not have grain boundaries in appearance when observed using a scanning electron microscope or the like at a field of view of 5,000 times or more and 30,000 times or less.

In this embodiment, "secondary particles" are particles in which the primary particles are aggregated. That is, the secondary particles are aggregates of primary particles. The secondary particles have multiple pores.

The CAM includes LiMO particles having pores and a compound containing Si located within the pores. When the Si-containing compound is present in the pores, the Si-containing compound strengthens the bond between the LiMO crystals between the pore surfaces. As a result, even if the lithium secondary battery is repeatedly charged and discharged, cracks are less likely to occur, and the cycle retention rate can be improved. In addition, the presence of Si-containing compounds between the primary particles and within the pores facilitates the formation of conductive Li-containing Si compounds during the charging and discharging process, improving the discharge rate characteristics of lithium secondary batteries. can do.

FIG. 1 is a SEM cross-sectional image of CAM, and FIG. 2 is an image in which a mapping image of Si element is superimposed on the SEM cross-sectional image of CAM. In FIG. 2, the portions where the Si element is confirmed in the mapping image are indicated by hatching so that the portions where the Si element is present are clearly shown. As can be seen from FIG. 2, compounds containing Si exist within the pores.

Compounds containing Si include SiO, SiO ₂ , H ₄ SiO ₄ , H ₆ Si ₂ O ₇ , H ₂ SiO ₃ , H ₂ Si ₂ O ₅ , Li ₂ Si ₅ O ₁₁ , Li ₄ SiO ₄ , Li ₂ SiO ₃ may be included. Since the Li-containing Si compound has lithium ion conductivity, the discharge rate characteristics of the lithium secondary battery are improved.

The ratio of the amount of Si to the total amount of the element M contained in Si and LiMO is greater than 0 mol% and less than 5.0 mol%, preferably less than 0.1-3.0 mol%, More preferably, it is 0.1-2.0 mol% or less. If the ratio of the amount of Si to the total amount of Si and element M is greater than 0 mol %, the bond between the LiMO crystals can be strengthened. When the ratio of the amount of Si to the total amount of materials of Si and element M is 5 mol % or less, Li diffusivity is excellent and high capacity can be easily obtained. If the ratio of the amount of Si material to the total amount of materials of Si and element M exceeds 5 mol %, Li diffusivity decreases, which tends to cause a decrease in capacity.

In this embodiment, the particle strength of the CAM is expressed as the ratio of the 50% cumulative volume particle size before and after the powder compaction process. Specifically, the particle strength of the CAM is defined as B ₅₀ / which is the ratio of the 50% cumulative volume particle size B ₅₀ of the CAM after compaction at 35 MPa to the 50% cumulative volume particle size A ₅₀ of the CAM before compaction. It is expressed as _A50 .

B ₅₀ /A ₅₀ is 0.92-1.00. B ₅₀ /A ₅₀ is preferably 0.93 or more, more preferably 0.94 or more. The upper limit of B ₅₀ /A ₅₀ is preferably 1.00, but may be 0.99 or 0.98. The upper and lower limits of B ₅₀ /A ₅₀ can be arbitrarily combined, and may be, for example, 0.93-0.99 or 0.94-0.98. When B ₅₀ /A ₅₀ is 0.92-1.00, cracks are less likely to occur even when the lithium secondary battery is repeatedly charged and discharged, and the cycle retention rate can be improved.

B ₁₀ /A ₁₀ , which is the ratio of 10% cumulative volume particle size B ₁₀ of CAM after powder compaction treatment at 35 MPa to 10% cumulative volume particle diameter A ₁₀ of CAM before powder compaction processing, shall be 0.93 or more. is preferable, and more preferably 0.94 or more. The upper limit of B ₁₀ /A ₁₀ is preferably 1.00, but may be 0.99 or 0.98. The upper and lower limits of B ₁₀ /A ₁₀ can be arbitrarily combined, and may be, for example, 0.93-0.99 or 0.94-0.98. When B ₁₀ /A ₁₀ is 0.93-1.00, cracks are less likely to occur even when the lithium secondary battery is repeatedly charged and discharged, and the cycle retention rate can be improved.

B ₉₀ /A ₉₀ , which is the ratio of the 90% cumulative volume particle size B ₉₀ of CAM after powder compaction at 35 MPa to the 90% cumulative volume particle size A ₉₀ of CAM before powder compaction, is 0.94 or more. is preferable, and more preferably 0.95 or more. The upper limit value of B ₉₀ /A ₉₀ is preferably 1.00, but may be 0.99 or 0.98. The upper and lower limits of B ₉₀ /A ₉₀ can be arbitrarily combined, and may be, for example, 0.94-0.99 or 0.95-0.98. When B ₉₀ /A ₉₀ is 0.94-1.00 or less, cracks are less likely to occur even when the lithium secondary battery is repeatedly charged and discharged, and the cycle retention rate can be improved.

[Powder processing]
The powder compaction process in this embodiment will be explained with reference to FIG. 3. The powder processing apparatus 40 shown in FIG. 3 includes jigs 41, 42, and 43.

The jig 41 has a cylindrical shape. The internal space 41a of the jig 41 has a cylindrical shape. The inner diameter LD of the inner space 41a is 15 mm.

The jig 42 has a cylindrical plug portion 421 and a flange portion 422 connected to the plug portion 421. The plug part 421 and the flange part 422 are connected at the center of the flange part 422 in a plan view. The diameter of the plug portion 421 is equal to the inner diameter LD of the jig 41, and is large enough to fit into the internal space 41a of the jig 41 without any gap.

The jig 43 has the same shape as the jig 42 and includes a cylindrical plug portion 431 and a flange portion 432 connected to the plug portion 431. The diameter of the plug portion 431 is equal to the inner diameter LD of the jig 41, and is large enough to fit into the internal space 41a of the jig 41 without any gap.

The powder processing apparatus 40 has a plug 421 of a jig 42 inserted into an opening at one end of the jig 41, and a plug 431 of a jig 43 inserted into an opening at the other end of the jig 41. use

To perform powder compaction using the compaction processing apparatus 40, first, the jig 42 is fitted to the jig 41, and with the flange portion 422 in contact with the jig 41, the object to be measured is placed in the internal space 41a. Fill with 3g of powder X, ie CAM. Next, the jig 43 is fitted onto the jig 41, and the tip of the plug portion 431 is brought into contact with the CAM.

Next, a load F is applied to the jig 43 using a press machine, and the load F is applied to the CAM in the internal space 41a for 1 minute to 35 MPa via the jig 43.

After the load is stopped and released, the CAM is taken out from the powder processing apparatus 40, and the cumulative volume particle sizes, that is, B _{10 ,} B ₅₀ , and B ₉₀ are measured by the method described in [Cumulative volume particle size] above. Note that the 35 MPa applied to the CAM corresponds to the pressure required when the electrode density is considered to be 3.00 g/cc when producing the electrode.

The BET specific surface area of CAM is preferably 2.0 m ² /g or less, more preferably 0.1-2.0 m ² /g, and 0.2-2.0 m ² /g. is even more preferable. When the BET specific surface area of the CAM is 0.1 m ² /g or more, it is easy to contact with the electrolyte and the battery capacity is improved. When the BET specific surface area of the CAM is 2 m ² /g or less, the presence of a compound containing Si between the primary particles and in the pores of the secondary particles facilitates electrical conduction and increases the discharge capacity.

LiMO may include Ni and element X as element M. Element X is at least one element selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, B, S, and P. . It is preferable that the material ratio of Li, Ni, and element X contained in the CAM satisfies the following formula (I). Here, the Li contained in CAM means Li contained when a compound containing Li and Si contained in LiMO particles contains Li.
[Li]:[Ni]:[X]=b:(1-a):a (I)
(However, 0.9≦b≦1.2 and 0<a≦0.2)

From the viewpoint of suppressing the increase in resistance of the battery after repeated charge/discharge cycles, a in the formula (I) is larger than 0, preferably 0.01 or more, and more preferably 0.02 or more. preferable. Further, from the viewpoint of obtaining a lithium secondary battery with a high initial capacity, a in the above formula (I) is 0.2 or less, preferably 0.1 or less, and more preferably 0.05 or less. .

From the viewpoint of obtaining a lithium secondary battery with a high cycle maintenance rate, element X may be one or more metals selected from the group consisting of Co, Mn, Ti, Mg, Al, W, B, and Zr. Preferably, one or more metals selected from the group consisting of Co, Mn, Al, W, and B are more preferable.

From the viewpoint of obtaining a lithium secondary battery with a high cycle maintenance rate, the ratio of the amount of Li to the amount of element M is preferably 0.98 or more, more preferably 1.04 or more, and particularly preferably 1.05 or more. . Further, from the viewpoint of obtaining a lithium secondary battery with higher initial Coulombic efficiency, the ratio of the amount of Li to the amount of element M is preferably 1.20 or less, more preferably 1.10 or less.

The upper limit and lower limit of the ratio of the amount of Li to the amount of element M can be arbitrarily combined. As for the combination, for example, the ratio of the amount of Li to the amount of element M is 0.98 or more and 1.20 or less, 1.04 or more and 1.10 or less, 1.05 or more and 1.10 or less, etc. can be mentioned.

The crystal structure of LiMO is a layered rock salt structure, and more preferably a hexagonal crystal structure or a monoclinic crystal structure.

The hexagonal crystal structure is P3, P3 ₁ , P3 ₂ , R3, P-3, R-3, P312, P321, P3 ₁ 12, P3 ₁ 21, P3 ₂ 12, P3 ₂ 21, R32, P3m1, P31m, P3c1, P31c, R3m, R3c, P-31m, P-31c, P-3m1, P-3c1, R-3m, R-3c, P6, P6 ₁ , P6 ₅ , P6 ₂ , P6 ₄ , P6 ₃ , P-6, P6/m, P6 ₃ /m, P622, P6 ₁ 22, P6 ₅ 22, P6 ₂ 22, P6 ₄ 22, P6 ₃ 22, P6 mm, P6 cc, P6 ₃ cm, P6 ₃ mc, P- 6m2, P-6c2, P-62m, P-62c, P6/mmm, P6/mcc, P6 ₃ /mcm, and P6 ₃ /mmc.

The monoclinic crystal structure is P2, P2 ₁ , C2, Pm, Pc, Cm, Cc, P2/m, P2 ₁ /m, C2/m, P2/c, P2 ₁ /c, and C2 It belongs to any one space group selected from the group consisting of /c.

Among these, in order to obtain a lithium secondary battery with high discharge capacity, the crystal structure is a hexagonal crystal structure belonging to space group R-3m or a monoclinic crystal structure belonging to C2/m. Particularly preferred is the structure.

The CAM described above has high particle strength, and cracks are unlikely to occur in the CAM even when the lithium secondary battery is repeatedly charged and discharged. As a result, the cycle maintenance rate of the lithium secondary battery can be improved. In addition, the presence of Si-containing compounds between the primary particles and within the pores facilitates the formation of conductive Li-containing Si compounds during the charging and discharging process, improving the discharge rate characteristics of lithium secondary batteries. can do.

<CAM manufacturing method>
The method for manufacturing a CAM of the present embodiment includes a step of mixing MCC and a solution containing Si to obtain a mixture, a step of drying the mixture to obtain a Si-containing MCC, and a step of mixing the Si-containing MCC and a lithium compound. and firing.

The CAM manufacturing method may further include an MCC manufacturing process.

The method for manufacturing the CAM of this embodiment, including the process for manufacturing the MCC, will be described below.

(1) Production of MCC MCC may be any of a metal composite hydroxide containing element M, a metal composite oxide containing element M, and a mixture thereof. The metal composite hydroxide and the metal composite oxide contain Ni, which is the element M, and the element X, in a molar ratio represented by the following formula (I'), as an example.
Ni:X=(1-a):a (I')
(In formula (I'), X is selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, B, S and P. represents one or more elements, and satisfies 0<a≦0.2.)

Hereinafter, a method for manufacturing MCC containing Co and Mn as the element X will be described as an example. First, a metal composite hydroxide containing Ni, Co and Mn is prepared. The metal composite hydroxide can be produced by a commonly known batch coprecipitation method or continuous coprecipitation method.

Specifically, by the continuous coprecipitation method described in JP-A-2002-201028, a nickel salt solution, a cobalt salt solution, a manganese salt solution, and a complexing agent are reacted to form Ni _(1-a) Co _z A metal composite hydroxide represented by Mn _w (OH) ₂ (z+w=a) is produced.

The nickel salt that is the solute of the nickel salt solution is not particularly limited, and for example, at least one of nickel sulfate, nickel nitrate, nickel chloride, and nickel acetate can be used.

As the cobalt salt that is the solute of the cobalt salt solution, for example, at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, and cobalt acetate can be used.

As the manganese salt that is the solute of the manganese salt solution, for example, at least one of manganese sulfate, manganese nitrate, manganese chloride, and manganese acetate can be used.

The above metal salts are used in a proportion corresponding to the composition ratio of Ni _(1-a) Co _z Mn _w (OH) ₂ described above. That is, the amounts of each metal salt are defined so that the molar ratio of Ni, Co, and Mn in the mixed solution containing the metal salts corresponds to (1-a):z:w. Additionally, water is used as a solvent.

The complexing agent is one that can form a complex with nickel ions, cobalt ions, and manganese ions in an aqueous solution, such as an ammonium ion donor (ammonium hydroxide, ammonium sulfate, ammonium chloride, ammonium carbonate, or ammonium fluoride). etc.), hydrazine, ethylenediaminetetraacetic acid, nitrilotriacetic acid and uracil diacetic acid and glycine.

In the manufacturing process of metal composite hydroxide, a complexing agent may or may not be used. If a complexing agent is used, the amount of the complexing agent contained in the mixture containing the nickel salt solution, cobalt salt solution, manganese salt solution and the complexing agent is determined by the amount of the complexing agent, e.g. metal salts (nickel salts, cobalt salts and manganese salts). The molar ratio to the total number of moles is greater than 0 and less than or equal to 2.0.

In the coprecipitation method, in order to adjust the pH value of the mixed solution containing the nickel salt solution, cobalt salt solution, manganese salt solution, and complexing agent, the mixed solution should be adjusted before the pH of the mixed solution changes from alkaline to neutral. Add an alkali metal hydroxide to. The alkali metal hydroxide is, for example, sodium hydroxide or potassium hydroxide.

Note that the pH value in this specification is defined as a value measured when the temperature of the liquid mixture is 40°C. The pH of the mixed solution is measured when the temperature of the mixed solution sampled from the reaction tank reaches 40°C. If the temperature of the sampled liquid mixture is lower than 40°C, the mixed liquid is heated to 40°C and the pH is measured. If the temperature of the sampled mixed liquid exceeds 40°C, the mixed liquid is cooled to 40°C and the pH is measured.

In addition to the above nickel salt solution, cobalt salt solution, and manganese salt solution, when a complexing agent is continuously supplied to the reaction tank, Ni, Co, and Mn react, forming Ni _(1-a) Co _z Mn _w (OH ) ₂ is generated.

During the reaction, the temperature of the reaction vessel is controlled within the range of, for example, 20-80°C, preferably 30-70°C.

Further, during the reaction, the pH value in the reaction tank is controlled within the range of pH 9-13, for example.

The reaction precipitate formed in the reaction tank is neutralized while stirring. The time for neutralizing the reaction precipitate is, for example, 1 to 20 hours.

As the reaction tank used in the continuous coprecipitation method, an overflow type reaction tank can be used to separate the formed reaction precipitate.

When producing a metal composite hydroxide by a batch coprecipitation method, a reaction tank is equipped with a reaction tank without an overflow pipe and a concentration tank connected to the overflow pipe, and the overflowing reaction precipitate is collected in the concentration tank. Examples include devices that have a mechanism for concentrating and circulating it back to the reaction tank.

Various gases, for example, inert gases such as nitrogen, argon or carbon dioxide, oxidizing gases such as air or oxygen, or mixed gases thereof may be supplied into the reaction vessel.

After the above reaction, the neutralized reaction precipitate is isolated. For isolation, a method is used in which, for example, a slurry containing a reaction precipitate (that is, a coprecipitate slurry) is dehydrated by centrifugation, suction filtration, or the like.

The isolated reaction precipitate is washed, dehydrated, dried and sieved to obtain a metal composite hydroxide containing Ni, Co and Mn.

The reaction precipitate is preferably washed with water or an alkaline washing liquid. In this embodiment, it is preferable to wash with an alkaline cleaning liquid, and more preferably to wash with an aqueous sodium hydroxide solution. Alternatively, cleaning may be performed using a cleaning liquid containing elemental sulfur. Examples of the cleaning liquid containing elemental sulfur include potassium and sodium sulfate aqueous solutions.

When MCC is a metal composite oxide, the metal composite hydroxide is heated to produce the metal composite oxide. Specifically, the metal composite hydroxide is heated at 400-700°C. Multiple heating steps may be performed if necessary. The heating temperature in this specification means the set temperature of the heating device. When there are multiple heating steps, it means the temperature at the time of heating at the highest holding temperature among each heating step.

The heating temperature is preferably 400-700°C, more preferably 450-680°C. When the heating temperature is 400 to 700° C., the metal composite hydroxide is sufficiently oxidized and a metal composite oxide having a BET specific surface area within an appropriate range can be obtained. If the heating temperature is less than 400°C, the metal composite hydroxide may not be sufficiently oxidized. If the heating temperature exceeds 700° C., the metal composite hydroxide may be excessively oxidized, and the BET specific surface area of the metal composite oxide may become too small.

The time for holding at the heating temperature may be 0.1 to 20 hours, preferably 0.5 to 10 hours. The rate of temperature increase to the heating temperature is, for example, 50-400° C./hour. Further, as the heating atmosphere, air, oxygen, nitrogen, argon, or a mixed gas thereof can be used.

The inside of the heating device may have an appropriate oxygen-containing atmosphere. The oxygen-containing atmosphere may be a mixed gas atmosphere of an inert gas and an oxidizing gas, or may be a state in which an oxidizing agent is present in an inert gas atmosphere. By providing an appropriate oxygen-containing atmosphere within the heating device, the transition metal contained in the metal composite hydroxide is appropriately oxidized, making it easier to control the form of the metal composite oxide.

The oxygen and oxidizing agent in the oxygen-containing atmosphere need only contain enough oxygen atoms to oxidize the transition metal.

When the oxygen-containing atmosphere is a mixed gas atmosphere of an inert gas and an oxidizing gas, the atmosphere inside the heating device can be controlled by venting the oxidizing gas into the heating device or bubbling the oxidizing gas into the mixed liquid. This can be done using the following method.

As the oxidizing agent, peroxides such as hydrogen peroxide, peroxide salts such as permanganates, perchlorates, hypochlorites, nitric acid, halogens, or ozone can be used.

Through the above steps, MCC can be manufactured.

(2) Mixing and drying of solution containing MCC and Si This step is a step of mixing MCC and a solution containing Si to obtain a mixture. As the solution containing Si, for example, an aqueous Li ₂ Si ₅ O ₁₁ solution or the like can be used.

A solution containing Si is added to MCC to form a slurry. At this time, the ratio of the amount of Si to the total amount of Ni, Co, Mn, and Si in the slurry is greater than 0 mol% and 5.0 mol% or less, and may be 0.1-3.0 mol%. It is preferably 0.1-2.0 mol%, more preferably 0.1-2.0 mol%.

The ratio of the mass of the Si-containing solution to the total mass of the slurry is not particularly limited, but is preferably 20% by mass or more, and more preferably 30% by mass or more. When the mass ratio of the Si-containing solution to the total mass of the slurry is 20% by mass or more, the MCC and the Si-containing solution are brought into sufficient contact. When the mass ratio of the Si-containing solution to the total mass of the slurry is 30% by mass or more, it is easy to control the ratio of Si contained in the obtained Si-added MCC.

Preferably, the slurry is stirred. The stirring time is preferably 1 to 30 minutes, more preferably 5 to 10 minutes, in order to bring the Si-containing solution into sufficient contact with MCC. Preferably, the slurry is stirred and then filtered to separate the solution.

(3) Drying the mixture This step is a step of drying the mixture to obtain Si-containing MCC. Drying can be carried out in an air atmosphere, an oxygen atmosphere, a nitrogen atmosphere, etc., but vacuum drying is preferably carried out. The drying temperature is preferably 100°C or higher, more preferably 120°C or higher. When the drying temperature is 100° C. or higher, water contained in MCC can be easily removed. After drying, a Si-doped MCC is obtained. After drying the Si-added MCC, classification may be performed as appropriate.

(4) Mixing Si-added MCC and lithium compound This step is a step of mixing and firing Si-added MCC and lithium compound.

As the lithium compound used in this embodiment, at least one of lithium carbonate, lithium nitrate, lithium acetate, lithium hydroxide, lithium oxide, lithium chloride, and lithium fluoride can be used. Among these, either lithium hydroxide or lithium carbonate or a mixture thereof is preferred. Further, when lithium hydroxide contains lithium carbonate, the content of lithium carbonate in lithium hydroxide is preferably 5% by mass or less.

The lithium compound and the Si-added MCC are mixed in consideration of the composition ratio of the final target product. Specifically, the amount (molar ratio) of lithium atoms to the total amount 1 of Ni, Co, and Mn contained in the Si-added MCC is preferably 0.98 or more, more preferably 1.04 or more, and 1.05 or more. is particularly preferred. A fired product is obtained by firing a mixture of a lithium compound and Si-added MCC as explained later. The upper limit of the amount (molar ratio) of lithium atoms to the total amount 1 of Ni, Co, and Mn contained in the MCC is preferably 1.20 or less, more preferably 1.10 or less.

The firing temperature is not particularly limited, but is preferably 650-900°C, more preferably 680-850°C, particularly preferably 700-820°C. When the firing temperature is 600° C. or higher, a CAM having a strong crystal structure can be obtained. Further, when the firing temperature is 900° C. or lower, volatilization of lithium on the surface of the CAM particles can be reduced.

In this specification, the firing temperature refers to the temperature of the atmosphere inside the firing furnace, and is the maximum temperature held in the main firing process (hereinafter sometimes referred to as the maximum holding temperature), and is the temperature of the atmosphere in the firing furnace. In the case of the main firing step, it means the temperature at the time of heating at the highest holding temperature among each heating step. The upper and lower limits of the firing temperature can be arbitrarily combined.

The holding time during firing is preferably 3 to 50 hours, more preferably 4 to 20 hours. If the holding time during firing exceeds 50 hours, the battery performance tends to deteriorate substantially due to volatilization of lithium. If the holding time during firing is less than 3 hours, crystal development will be poor and battery performance will tend to deteriorate.

In this embodiment, the temperature increase rate in the heating step to reach the maximum holding temperature is preferably 80° C./hour or more, more preferably 100° C./hour or more, and particularly preferably 150° C./hour or more. The rate of temperature increase in the heating step at which the maximum holding temperature is reached is calculated from the time from when the temperature rise starts until the holding temperature is reached in the baking device.

Preferably, the firing process includes a plurality of firing stages at different firing temperatures. For example, it is preferable to have a first firing stage and a second firing stage in which firing is performed at a higher temperature than the first firing stage. Furthermore, it may have firing stages with different firing temperatures and firing times.

As the firing atmosphere, air, oxygen, nitrogen, argon, or a mixed gas thereof is used depending on the desired composition, and a plurality of firing steps are performed if necessary.

The mixture of Si-doped MCC and lithium compound may be fired in the presence of an inert melting agent. The inert melting agent is added to an extent that does not impair the initial capacity of a battery using CAM, and may remain in the fired product. As the inert melting agent, for example, those described in WO2019/177032A1 can be used.

Note that the mixture of Si-added MCC and lithium compound may be pre-fired before performing the firing step. In this embodiment, pre-firing means firing at a temperature lower than the firing temperature in the firing process. The firing temperature during temporary firing is, for example, in the range of 400°C or more and less than 700°C. Temporary firing may be performed multiple times.

The firing device used during firing is not particularly limited, and for example, either a continuous firing furnace or a fluidized fluidized firing furnace may be used. Continuous firing furnaces include tunnel furnaces and roller hearth kilns. A rotary kiln may be used as the fluidized firing furnace.

As described above, a CAM can be obtained by firing a mixture of Si-containing MCC and a lithium compound.

<Lithium secondary battery>
Next, the configuration of a suitable lithium secondary battery when using the CAM of this embodiment will be explained.
Furthermore, a positive electrode for a lithium secondary battery (hereinafter sometimes referred to as a positive electrode) suitable for using the CAM of this embodiment will be described.
Furthermore, a lithium secondary battery suitable for use as a positive electrode will be explained.

An example of a suitable lithium secondary battery using the CAM of this embodiment includes a positive electrode and a negative electrode, a separator sandwiched between the positive electrode and the negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode.

An example of a lithium secondary battery includes a positive electrode and a negative electrode, a separator sandwiched between the positive electrode and the negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode.

FIG. 4 is a schematic diagram showing an example of a lithium secondary battery. The cylindrical lithium secondary battery 10 of this embodiment is manufactured as follows.

First, as shown in FIG. 4, a pair of band-shaped separators 1, a band-shaped positive electrode 2 having a positive electrode lead 21 at one end, and a band-shaped negative electrode 3 having a negative electrode lead 31 at one end are placed between the separator 1, the positive electrode 2, and the separator. 1 and negative electrode 3 are laminated in this order and wound to form an electrode group 4.

Next, after housing the electrode group 4 and an insulator (not shown) in the battery can 5, the bottom of the can is sealed, the electrode group 4 is impregnated with the electrolyte 6, and the electrolyte is placed between the positive electrode 2 and the negative electrode 3. . Furthermore, by sealing the upper part of the battery can 5 with the top insulator 7 and the sealing body 8, the lithium secondary battery 10 can be manufactured.

The shape of the electrode group 4 is, for example, a columnar shape in which the cross-sectional shape when the electrode group 4 is cut in a direction perpendicular to the winding axis is a circle, an ellipse, a rectangle, or a rectangle with rounded corners. can be mentioned.

Further, as the shape of the lithium secondary battery having such an electrode group 4, a shape defined by IEC60086, which is a standard for batteries established by the International Electrotechnical Commission (IEC), or JIS C 8500 can be adopted. . For example, the shape may be cylindrical or square.

Furthermore, the lithium secondary battery is not limited to the above-mentioned wound type configuration, but may have a laminated type configuration in which a laminated structure of a positive electrode, a separator, a negative electrode, and a separator are repeatedly stacked. Examples of stacked lithium secondary batteries include so-called coin-type batteries, button-type batteries, and paper-type (or sheet-type) batteries.

Each configuration will be explained in order below.
(positive electrode)
The positive electrode of this embodiment can be manufactured by first preparing a positive electrode mixture containing a CAM, a conductive material, and a binder, and then supporting the positive electrode mixture on a positive electrode current collector.

(conductive material)
A carbon material can be used as the conductive material included in the positive electrode of this embodiment. Examples of carbon materials include graphite powder, carbon black (eg, acetylene black), and fibrous carbon materials.

The proportion of the conductive material in the positive electrode mixture is preferably 5 parts by mass or more and 20 parts by mass or less based on 100 parts by mass of the CAM.

(binder)
As the binder included in the positive electrode of this embodiment, a thermoplastic resin can be used. Examples of this thermoplastic resin include polyimide resins; fluororesins such as polyvinylidene fluoride (hereinafter sometimes referred to as PVdF) and polytetrafluoroethylene; polyolefin resins such as polyethylene and polypropylene; described in WO2019/098384A1 or US2020/0274158A1 The following resins can be mentioned.

(Positive electrode current collector)
As the positive electrode current collector included in the positive electrode of this embodiment, a band-shaped member made of a metal material such as Al, Ni, or stainless steel can be used.

As a method for supporting the positive electrode mixture on the positive electrode current collector, the positive electrode mixture is made into a paste using an organic solvent, and the resulting paste of the positive electrode mixture is applied to at least one side of the positive electrode current collector and dried. An example of this method is to perform an electrode pressing process to fix the electrode.

When the positive electrode mixture is made into a paste, an example of an organic solvent that can be used is N-methyl-2-pyrrolidone (hereinafter sometimes referred to as NMP).

Examples of the method for applying the positive electrode mixture paste to the positive electrode current collector include a slit die coating method, a screen coating method, a curtain coating method, a knife coating method, a gravure coating method, and an electrostatic spray method.

A positive electrode can be manufactured by the method listed above.
(Negative electrode)
The negative electrode of the lithium secondary battery of this embodiment only needs to be capable of doping and dedoping lithium ions at a lower potential than the positive electrode, and the negative electrode mixture containing the negative electrode active material is supported on the negative electrode current collector. Examples include an electrode consisting of a negative electrode active material alone, and an electrode consisting of a negative electrode active material alone.

(Negative electrode active material)
Examples of the negative electrode active material included in the negative electrode include carbon materials, chalcogen compounds (oxides, sulfides, etc.), nitrides, metals, and alloys, which can be doped and dedoped with lithium ions at a lower potential than the positive electrode. It will be done.

Examples of carbon materials that can be used as the negative electrode active material include graphites such as natural graphite and artificial graphite, cokes, carbon black, carbon fibers, and fired organic polymer compounds.

Oxides that can be used as negative electrode active materials include silicon oxides represented by the formula SiO _x (where x is a positive real number) _such as SiO ₂ and SiO _; , x is a positive real number); metal composite oxides containing lithium and titanium such as Li ₄ Ti ₅ O ₁₂ ;

Furthermore, examples of metals that can be used as the negative electrode active material include lithium metal, silicon metal, and tin metal.
As a material that can be used as a negative electrode active material, a material described in WO2019/098384A1 or US2020/0274158A1 may be used.

These metals and alloys are mainly used alone as electrodes after being processed into a foil shape, for example.

Among the above negative electrode active materials, the potential of the negative electrode hardly changes from the uncharged state to the fully charged state during charging (good potential flatness), the average discharge potential is low, and the capacity retention rate when repeatedly charged and discharged is low. Carbon materials containing graphite as a main component, such as natural graphite and artificial graphite, are preferably used because of their high performance (good cycle characteristics). The shape of the carbon material may be, for example, flaky like natural graphite, spherical like mesocarbon microbeads, fibrous like graphitized carbon fiber, or aggregates of fine powder.

The negative electrode mixture may contain a binder, if necessary. Examples of the binder include thermoplastic resins, specifically PVdF, thermoplastic polyimide, carboxymethyl cellulose (hereinafter sometimes referred to as CMC), and styrene-butadiene rubber (hereinafter sometimes referred to as SBR). Mention may be made of polyethylene and polypropylene.

(Negative electrode current collector)
Examples of the negative electrode current collector included in the negative electrode include a band-shaped member made of a metal material such as Cu, Ni, or stainless steel.

The negative electrode mixture can be supported on such a negative electrode current collector, as in the case of the positive electrode, by pressure molding, by forming a paste using a solvent, applying it onto the negative electrode current collector, drying, and then pressing. An example is a method of crimping.

(Separator)
The separator included in the lithium secondary battery of this embodiment may be in the form of a porous membrane, nonwoven fabric, woven fabric, etc. made of a material such as a polyolefin resin such as polyethylene or polypropylene, a fluororesin, or a nitrogen-containing aromatic polymer. A material having the following properties can be used. Further, the separator may be formed using two or more of these materials, or may be formed by laminating these materials. Alternatively, a separator described in JP-A-2000-030686 or US20090111025A1 may be used.

(electrolyte)
The electrolytic solution included in the lithium secondary battery of this embodiment contains an electrolyte and an organic solvent.

Examples of the electrolyte contained in the electrolytic solution include lithium salts such as LiClO ₄ , LiPF ₆ , and LiBF ₄ , and a mixture of two or more of these may be used.

Further, as the organic solvent contained in the electrolytic solution, carbonates such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate can be used.

As the organic solvent, it is preferable to use a mixture of two or more of these. Among these, mixed solvents containing carbonates are preferred, and mixed solvents of cyclic carbonates and acyclic carbonates and mixed solvents of cyclic carbonates and ethers are more preferred.

Further, as the electrolytic solution, it is preferable to use an electrolytic solution containing a lithium salt containing fluorine such as LiPF ₆ and an organic solvent having a fluorine substituent, in order to increase the safety of the obtained lithium secondary battery.
As the electrolyte and organic solvent contained in the electrolytic solution, the electrolyte and organic solvent described in WO2019/098384A1 or US2020/0274158A1 may be used.

<All-solid-state lithium secondary battery>
Next, while explaining the configuration of an all-solid lithium secondary battery, a positive electrode using LiMO according to one embodiment of the present invention as a CAM of an all-solid lithium secondary battery, and an all-solid lithium secondary battery having this positive electrode will be explained. do.

FIG. 5 is a schematic diagram showing an example of the all-solid-state lithium secondary battery of this embodiment. An all-solid-state lithium secondary battery 1000 shown in FIG. 5 includes a laminate 100 having a positive electrode 110, a negative electrode 120, and a solid electrolyte layer 130, and an exterior body 200 housing the laminate 100. Further, the all-solid-state lithium secondary battery 1000 may have a bipolar structure in which a positive electrode active material and a negative electrode active material are arranged on both sides of a current collector. A specific example of the bipolar structure is, for example, the structure described in JP-A-2004-95400. The materials constituting each member will be described later.

The laminate 100 may include an external terminal 113 connected to the positive electrode current collector 112 and an external terminal 123 connected to the negative electrode current collector 122. In addition, the all-solid-state lithium secondary battery 1000 may include a separator between the positive electrode 110 and the negative electrode 120.

The all-solid-state lithium secondary battery 1000 further includes an insulator (not shown) that insulates the stacked body 100 and the exterior body 200 and a sealing body (not shown) that seals the opening 200a of the exterior body 200.

For the exterior body 200, a container made of a highly corrosion-resistant metal material such as aluminum, stainless steel, or nickel-plated steel can be used. Further, as the exterior body 200, a container formed by processing a laminate film into a bag shape, which has been subjected to anti-corrosion treatment on at least one surface, can also be used.

Examples of the shape of the all-solid-state lithium secondary battery 1000 include a coin shape, a button shape, a paper shape (or sheet shape), a cylindrical shape, a square shape, and a laminate shape (pouch shape).

Although the all-solid-state lithium secondary battery 1000 is illustrated as having one laminate 100 as an example, the present embodiment is not limited to this. The all-solid-state lithium secondary battery 1000 may have a configuration in which the laminate 100 is used as a unit cell, and a plurality of unit cells (the laminate 100) are sealed inside an exterior body 200.

Each configuration will be explained in order below.

(positive electrode)
The positive electrode 110 of this embodiment includes a positive electrode active material layer 111 and a positive electrode current collector 112.

The positive electrode active material layer 111 includes the above-described CAM, which is one embodiment of the present invention, and a solid electrolyte. Further, the positive electrode active material layer 111 may contain a conductive material and a binder.

(solid electrolyte)
As the solid electrolyte included in the positive electrode active material layer 111 of this embodiment, a solid electrolyte that has lithium ion conductivity and is used in known all-solid-state lithium secondary batteries can be employed. Such solid electrolytes include inorganic electrolytes and organic electrolytes. Examples of the inorganic electrolyte include oxide-based solid electrolytes, sulfide-based solid electrolytes, and hydride-based solid electrolytes. Examples of the organic electrolyte include polymer solid electrolytes. Examples of each electrolyte include compounds described in WO2020/208872A1, US2016/0233510A1, US2012/0251871A1, and US2018/0159169A1, such as the following compounds.

(Oxide solid electrolyte)
Examples of the oxide-based solid electrolyte include perovskite-type oxides, NASICON-type oxides, LISICON-type oxides, and garnet-type oxides. Specific examples of each oxide include compounds described in WO2020/208872A1, US2016/0233510A1, and US2020/0259213A1.

Perovskite type oxides include Li-La-Ti oxides such as Li _a La _1-a TiO ₃ (0<a<1), Li _b La _1-b TaO ₃ (0<b<1), etc. Examples include Li-La-Ta oxides and Li-La-Nb oxides such as Li _c La _1-c NbO ₃ (0<c<1).

Examples of the NASICON type oxide include Li _1+d Al _d Ti _2-d (PO ₄ ) ₃ (0≦d≦1). NASICON type oxide is Li _m M1 _n M2 _o P _p O _q (wherein M1 is at least one selected from the group consisting of B, Al, Ga, In, C, Si, Ge, Sn, Sb and Se). M2 is at least one element selected from the group consisting of Ti, Zr, Ge, In, Ga, Sn, and Al. m, n, o, p, and q are any is a positive number).

The LISICON type oxide is Li ₄ M3O ₄ -Li ₃ M4O ₄ (M3 is at least one element selected from the group consisting of Si, Ge, and Ti. M4 is P, As, and V. (at least one element selected from the group).

Examples of the garnet type oxide include Li-La-Zr-based oxides such as Li ₇ La ₃ Zr ₂ O ₁₂ (also referred to as LLZ).

The oxide solid electrolyte may be a crystalline material or an amorphous material.

(Sulfide solid electrolyte)
Sulfide-based solid electrolytes include Li ₂ S-P ₂ S ₅ -based compounds, Li ₂ S-SiS _2- based compounds, Li ₂ S-GeS ₂ -based compounds, Li ₂ S-B ₂ S ₃ -based compounds, LiI- Examples include Si ₂ S-P ₂ S ₅ -based compounds, LiI-Li ₂ SP ₂ O ₅ -based compounds, LiI-Li ₃ PO ₄ -P ₂ S ₅ -based compounds, and Li ₁₀ GeP ₂ S ₁₂ . .

In this specification, the expression "compound" referring to a sulfide-based solid electrolyte refers to a solid electrolyte mainly containing raw materials such as "Li ₂ S" and "P ₂ S ₅ " described before "compound". Used as a general term for For example, the Li ₂ S--P ₂ S _5- based compound includes a solid electrolyte that mainly contains Li ₂ S and P ₂ S ₅ and further contains other raw materials. The proportion of Li ₂ S contained in the Li ₂ SP ₂ S ₅ compound is, for example, 50 to 90% by mass based on the entire Li ₂ SP ₂ S ₅ compound. The proportion of P ₂ S ₅ contained in the Li ₂ SP ₂ S ₅ compound is, for example, 10 to 50% by mass based on the entire Li ₂ SP ₂ S ₅ compound. Further, the proportion of other raw materials contained in the Li ₂ S--P ₂ S ₅ -based compound is, for example, 0 to 30% by mass with respect to the entire Li ₂ S--P ₂ S ₅ -based compound. Furthermore, the Li ₂ S--P ₂ S _5- based compounds also include solid electrolytes in which the mixing ratio of Li ₂ S and P ₂ S ₅ is varied.

Examples of Li ₂ S-P ₂ S _5- based compounds include Li ₂ S-P ₂ S ₅ , Li ₂ S-P ₂ S ₅ -LiI, Li ₂ S-P ₂ S ₅ -LiCl, Li ₂ S-P ₂ S ₅ -LiBr, Li ₂ S-P ₂ S ₅ -LiI-LiBr, Li ₂ S-P ₂ S ₅ -Li ₂ O, Li ₂ S-P ₂ S ₅ -Li ₂ O-LiI and Li ₂ S- Examples include P ₂ S ₅ -Z _m S _n (m and n are positive numbers. Z is Ge, Zn or Ga).

Examples of Li ₂ S-SiS _2- based compounds include Li ₂ S-SiS ₂ , Li ₂ S-SiS ₂ -LiI, Li ₂ S-SiS ₂ -LiBr, Li ₂ S-SiS ₂ -LiCl, and Li ₂ S-SiS. ₂ -B ₂ S ₃ -LiI, Li ₂ S-SiS ₂ -P ₂ S ₅ -LiI, Li ₂ S-SiS ₂ -P ₂ S ₅ -LiCl, Li ₂ S-SiS ₂ -Li ₃ PO ₄ , Li ₂ S-SiS ₂ -Li ₂ SO ₄ and Li ₂ S-SiS ₂ -Li _x MO _y (x, y are positive numbers. M is P, Si, Ge, B, Al, Ga or In ).

Examples of the Li ₂ S-GeS _2- based compound include Li ₂ S-GeS ₂ and Li ₂ S-GeS ₂ -P ₂ S ₅ .

The sulfide-based solid electrolyte may be a crystalline material or an amorphous material.

(Hydride solid electrolyte)
Examples of hydride solid electrolyte materials include LiBH ₄ , LiBH ₄ -3KI, LiBH ₄ -PI ₂ , LiBH ₄ -P ₂ S ₅ , LiBH ₄ -LiNH ₂ , 3LiBH ₄ -LiI, LiNH ₂ , Li ₂ AlH ₆ , Li( _NH2 ) _2I , _Li2NH , LiGd( _BH4 ) _3Cl , _Li2 ( _BH4 )( _NH2 ), _Li3 ( _NH2 )I and _Li4 ( _BH4 )( _NH2 ) ₃ etc. can be mentioned.

(Polymer solid electrolyte)
Examples of the polymer solid electrolyte include organic polymer electrolytes such as polyethylene oxide-based polymer compounds and polymer compounds containing at least one selected from the group consisting of polyorganosiloxane chains and polyoxyalkylene chains. . Furthermore, a so-called gel type material in which a non-aqueous electrolyte is held in a polymer compound can also be used.

Two or more types of solid electrolytes can be used in combination as long as the effects of the invention are not impaired.

(Conductive material and binder)
As the conductive material included in the positive electrode active material layer 111 of this embodiment, the materials described in (Conductive Material) above can be used. Moreover, the ratio explained in the above-mentioned (electrically conductive material) can be similarly applied to the ratio of the conductive material in the positive electrode mixture. Further, as the binder included in the positive electrode, the material described in the above (binder) can be used.

(Positive electrode current collector)
As the positive electrode current collector 112 included in the positive electrode 110 of this embodiment, the material described in (Positive electrode current collector) above can be used.

Examples of a method for supporting the positive electrode active material layer 111 on the positive electrode current collector 112 include a method of pressure-molding the positive electrode active material layer 111 on the positive electrode current collector 112. Cold press or hot press can be used for pressure molding.

Further, a mixture of CAM, solid electrolyte, conductive material, and binder is made into a paste using an organic solvent to form a positive electrode mixture, and the resulting positive electrode mixture is applied onto at least one surface of the positive electrode current collector 112, dried, and pressed. The positive electrode active material layer 111 may be supported on the positive electrode current collector 112 by fixing.

Further, the mixture of CAM, solid electrolyte, and conductive material is made into a paste using an organic solvent to form a positive electrode mixture, and the resulting positive electrode mixture is applied onto at least one surface of the positive electrode current collector 112, dried, and sintered. In this way, the positive electrode active material layer 111 may be supported on the positive electrode current collector 112.

As the organic solvent that can be used for the positive electrode mixture, the same organic solvent that can be used when making a paste of the positive electrode mixture explained in the above (positive electrode current collector) can be used.

Examples of the method for applying the positive electrode mixture to the positive electrode current collector 112 include the method described in (Positive electrode current collector) above.

The positive electrode 110 can be manufactured by the method listed above. Specific combinations of materials used for the positive electrode 110 include CAM described in this embodiment and combinations described in Tables 1, 2, and 3.

(Negative electrode)
The negative electrode 120 includes a negative electrode active material layer 121 and a negative electrode current collector 122. The negative electrode active material layer 121 includes a negative electrode active material. Further, the negative electrode active material layer 121 may include a solid electrolyte and a conductive material. As the negative electrode active material, negative electrode current collector, solid electrolyte, conductive material, and binder, those described above can be used.

As a method for supporting the negative electrode active material layer 121 on the negative electrode current collector 122, as in the case of the positive electrode 110, a method of pressure molding, a method of applying a paste-like negative electrode mixture containing a negative electrode active material onto the negative electrode current collector 122, Examples include a method in which a paste-like negative electrode mixture containing a negative electrode active material is applied on the negative electrode current collector 122, dried, and then sintered.

(solid electrolyte layer)
The solid electrolyte layer 130 includes the solid electrolyte described above.

The solid electrolyte layer 130 can be formed by depositing an inorganic solid electrolyte on the surface of the positive electrode active material layer 111 included in the above-described positive electrode 110 by a sputtering method.

Further, the solid electrolyte layer 130 can be formed by applying a paste-like mixture containing a solid electrolyte to the surface of the positive electrode active material layer 111 included in the above-described positive electrode 110 and drying it. After drying, the solid electrolyte layer 130 may be formed by press molding and further pressurizing by cold isostatic pressing (CIP).

In the laminate 100, the negative electrode 120 is stacked on the solid electrolyte layer 130 provided on the positive electrode 110 using a known method so that the negative electrode active material layer 121 is in contact with the surface of the solid electrolyte layer 130. It can be manufactured by

Another aspect of the invention includes the following embodiments.
[1] A positive electrode active material for a lithium secondary battery comprising particles of a lithium metal composite oxide having pores and containing Li and element M, and a compound containing Si and located in the pores. The ratio of the amount of Si to the total amount of the elements M and Si is greater than 0 mol% and 5.0 mol% or less, B ₅₀ /A ₅₀ , which is the ratio of 50% cumulative volume particle size B ₅₀ of the positive electrode active material for lithium secondary batteries after compaction treatment at 35 MPa to % cumulative volume particle size A ₅₀ , is 0.93-0.99. A positive electrode active material for lithium secondary batteries.
[2] _The 10% cumulative volume particle size B of the positive electrode active material for a lithium secondary battery after the powder compaction process relative to the 10% cumulative volume particle size A ₁₀ of the positive electrode active material for a lithium secondary battery before the powder compaction process The positive electrode active material for a lithium secondary battery according to [1], wherein the ratio B ₁₀ /A ₁₀ is 0.94-0.98.
[3] The 90% cumulative volume particle size B of the positive electrode active material for lithium secondary batteries after the powder compacting process is ₉₀ relative to the 90% cumulative volume particle size A ₉₀ of the positive electrode active material for a lithium secondary battery before the compacting process. The positive electrode active material for a lithium secondary battery according to [1] or [2], wherein the ratio B ₉₀ /A ₉₀ is 0.94-0.99.
[4] The lithium metal composite oxide contains Ni and element X as the element M, and the element X is Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn. , Zr, Ga, B, S, and P, and the material amount ratio of Li, the Ni, and the element X contained in the positive electrode active material for lithium secondary batteries. is the positive electrode active material for a lithium secondary battery according to any one of [1] to [3], which satisfies the following formula (I).
[Li]:[Ni]:[X]=b:(1-a):a (I)
(However, 0.9≦b≦1.2 and 0<a≦0.2)
[5] The lithium secondary battery according to any one of [1] to [4], wherein the positive electrode active material for lithium secondary battery has a BET specific surface area of 0.2-2.0 m ² /g. Cathode active material.
[6] A positive electrode for a lithium secondary battery, comprising the positive electrode active material for a lithium secondary battery according to any one of [1] to [5].
[7] A lithium secondary battery having the positive electrode for a lithium secondary battery according to [6].
[8] A step of mixing a metal composite compound containing element M and a solution containing Si to obtain a mixture, a step of drying the mixture to obtain a Si-containing metal composite compound, and a step of mixing the Si-containing metal composite compound and lithium. A method for producing a positive electrode active material for a lithium secondary battery, comprising a step of mixing and firing a compound.
[9] In the step of obtaining the mixture, the solution containing the metal composite compound and the Si is prepared such that the ratio of the amount of Si to the total amount of the elements M and Si is 0.1 to 5.0 mol%. The method for producing a positive electrode active material for a lithium secondary battery according to [8], which comprises mixing the following.
[10] The positive electrode active material for a lithium secondary battery includes Li and a lithium metal composite oxide containing Ni and element X as the element M, where the element X is Co, Mn, Fe, Cu, Ti, Li is at least one element selected from the group consisting of Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, B, S, and P, and is contained in the positive electrode active material for lithium secondary batteries. The method for producing a positive electrode active material for a lithium secondary battery according to [8] or [9], wherein the material ratio of the Ni, and the element X satisfies the following formula (I).
[Li]:[Ni]:[X]=b:(1-a):a (I)
(However, 0.9≦b≦1.1 and 0<a≦0.15)

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to the following description.

<Composition analysis>
The compositional analysis of the CAM produced by the method described below was performed by the method of [Compositional Analysis] described above.

<Cross-sectional observation>
The presence or absence of pores in the CAM and the presence of Si-containing compounds within the pores were confirmed by SEM cross-sectional images and Si element mapping images.

<Cumulative volume particle size A ₁₀ , B ₁₀ , A ₅₀ , B ₅₀ , A ₉₀ and B ₉₀ >
Cumulative volume particle size A ₁₀ , B ₁₀ , A ₅₀ , B ₅₀ , A ₉₀ and B ₉₀ were measured by the measuring method described in [Cumulative volume particle size] and the method described in [Powder compaction] above.

<BET specific surface area>
The BET specific surface area of CAM was determined by the [BET specific surface area] measurement method.

<Production of positive electrode for lithium secondary battery>
CAM obtained by the manufacturing method described below, a conductive material (acetylene black), and a binder (PVdF) are added and kneaded so that the composition of CAM: conductive material: binder = 92:5:3 (mass ratio). A paste-like positive electrode mixture was prepared. When preparing the positive electrode mixture, N-methyl-2-pyrrolidone was used as an organic solvent.

The obtained positive electrode mixture was applied to a 20 μm thick Al foil serving as a current collector and vacuum dried at 150° C. for 8 hours to obtain a positive electrode for a lithium secondary battery. The electrode area of this positive electrode for a lithium secondary battery was 1.65 cm ² .

<Production of lithium secondary battery (coin type half cell)>
The following operations were performed in a glove box with an argon atmosphere.
Place the above-mentioned positive electrode for a lithium secondary battery on the bottom cover of a coin-type battery R2032 part (manufactured by Hosen Co., Ltd.) with the aluminum foil side facing down, and then place a heat-resistant porous film on top of it. A laminated film separator (thickness: 16 μm) having porous layers laminated thereon was placed. 300 μl of electrolyte was injected here. The electrolytic solution used was a liquid obtained by dissolving LiPF ₆ at 1 mol/l in a mixture of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate at a ratio of 30:35:35 (volume ratio).
Next, metal lithium is used as the negative electrode, placed on top of the separator, covered with a gasket, and crimped with a crimping machine to form a lithium secondary battery (coin-shaped half cell R2032. Hereinafter referred to as "coin-shaped half cell") ) was created.

<Cycle maintenance rate and discharge rate characteristics>
The initial discharge capacity, cycle maintenance rate, and discharge rate characteristics of the lithium secondary battery produced by the above method were measured and calculated by performing the above-mentioned [cycle test] and [discharge rate test].

(Example 1)
A metal composite hydroxide 1 having a composition of Ni _0.96 Co _0.02 Mn _0.02 (OH) ₂ was obtained by a known coprecipitation method using an aqueous solution of sulfates of nickel, cobalt, and manganese.

Metal composite hydroxide 1 was maintained and heated at 650° C. for 5 hours in the air, and then cooled to room temperature to obtain metal composite oxide 1.

An aqueous solution of Li ₂ Si ₅ O ₁₁ was added to the metal composite oxide 1 at a weight ratio of 50 wt % to form a slurry, and the slurry was stirred for 5 minutes. At this time, pure water was added to the Li ₂ Si ₅ O ₁₁ aqueous solution so that the molar ratio of Si to the total number of moles of Ni, Co, Mn, and Si was 0.5 mol% to adjust the concentration of the Li ₂ Si ₅ O ₁₁ aqueous solution. adjusted. Thereafter, the slurry was filtered for 2 minutes, and the filtered material was heated under vacuum at 120° C. for 10 hours to obtain Si-added metal composite oxide 1.

Lithium hydroxide was weighed so that the amount (molar ratio) of Li to the total amount 1 of Ni, Co, and Mn contained in the Si-added metal composite oxide 1 was 1.06. Mixture 1 was obtained by mixing Si-added metal composite oxide 1 and lithium hydroxide.

Next, the obtained mixture 1 was fired at 720° C. for 5 hours in an oxygen atmosphere to obtain CAM-1 containing a Si-containing compound located in the pores. The composition ratio (molar ratio) of CAM-1 was [Li]:[Ni]:[X]:[Si]=1.06:0.96:0.04:0.005.

(Example 2)
Except that an aqueous solution of Li ₂ Si ₅ O ₁₁ was added to the metal composite hydroxide 1 obtained by the above method so that the molar ratio of Si to the total number of moles of Ni, Co, Mn and Si was 1.0 mol%. obtained CAM-2 containing a compound containing Si located in the pores in the same manner as in Example 1. The composition ratio (mole ratio) of CAM-2 was [Li]:[Ni]:[X]:[Si]=1.06:0.96:0.04:0.01.

(Example 3)
Except that an aqueous solution of Li ₂ Si ₅ O ₁₁ was added to the metal composite hydroxide 1 obtained by the above method so that the molar ratio of Si to the total number of moles of Ni, Co, Mn and Si was 3.0 mol%. Using the same method as in Example 1, CAM-3 containing a compound containing Si located in the pores was obtained. The composition ratio (molar ratio) of CAM-3 was [Li]:[Ni]:[X]:[Si]=1.06:0.96:0.04:0.03.

(Example 4)
Except that an aqueous solution of Li ₂ Si ₅ O ₁₁ was added to the metal composite hydroxide 1 obtained by the above method so that the molar ratio of Si to the total number of moles of Ni, Co, Mn and Si was 5.0 mol%. obtained CAM-4 containing a Si-containing compound located in the pores in the same manner as in Example 1. The composition ratio (mole ratio) of CAM-4 was [Li]:[Ni]:[X]:[Si]=1.06:0.96:0.04:0.05.

(Comparative example 1)
Lithium hydroxide was weighed so that the amount (molar ratio) of lithium atoms to the total amount 1 of Ni, Co, and Mn contained in the metal composite oxide 1 obtained by the above method was 1.06. Mixture 2 was obtained by mixing metal composite oxide 1 and lithium hydroxide.

Next, mixture 2 was baked at 700° C. for 5 hours in an oxygen atmosphere to obtain CAM-C1. The composition ratio (mole ratio) of CAM-C1 was [Li]:[Ni]:[X]:[Si]=1.06:0.96:0.04:0.

(Comparative example 2)
Lithium hydroxide was weighed so that the amount (molar ratio) of Li to the total amount 1 of Ni, Co, and Mn contained in the metal composite oxide 1 obtained by the above method was 1.06. Silicon oxide was weighed so that the molar ratio of Si to the total amount 1 of Ni, Co, and Mn contained in the metal composite oxide 1 was 0.5 mol %. Mixture 3 was obtained by mixing metal composite oxide 1, lithium hydroxide, and silicon oxide.

Next, mixture 3 was fired at 700° C. for 5 hours in an oxygen atmosphere to obtain CAM-C2 containing a compound containing Si. The composition ratio (mole ratio) of CAM-C2 was [Li]:[Ni]:[X]:[Si]=1.06:0.96:0.04:0.005.

B _{50, A 50,} B _{50 /} A ₅₀ , B ₁₀ /A _{10 ,} B ₉₀ /A of CAM-1 to CAM-4 and CAM-C1 to CAM-C2 of Examples 1 to 4 and Comparative Examples 1 to 2 Table 4 shows the cycle maintenance rate and discharge rate characteristics of the coin-shaped half cell using ₉₀ , BET specific surface area, and each CAM.

B ₅₀ /A ₅₀ of CAM-1 to CAM-4 was 0.92 or more. The cycle retention rate of coin-shaped half cells using CAM-1 to CAM-4 was 83.7-95.7%, and the discharge rate characteristics were 74.2-85.4% or higher.

On the other hand, B ₅₀ /A ₅₀ of CAM-C1, which does not contain Si, was 0.89. The cycle maintenance rate of the coin-shaped half cell using CAM-C1 was 77.9% or less, and the discharge rate characteristic was 69.8% or less.

B ₅₀ /A ₅₀ of CAM-C2 containing Si as LiMO was 0.90. The cycle maintenance rate of the coin-shaped half cell using CAM-C2 was 79.7% or less, and the discharge rate characteristic was 78.6% or less.

According to the present invention, even if a lithium secondary battery is repeatedly charged and discharged, cracks do not easily occur in the positive electrode active material for a lithium secondary battery, and the lithium lithium battery can improve the cycle retention rate and discharge rate characteristics of the secondary battery. It is possible to provide a positive electrode active material for a secondary battery, a positive electrode for a lithium secondary battery using the same, a lithium secondary battery using the same, and a method for producing a positive electrode active material for a lithium secondary battery.

DESCRIPTION OF SYMBOLS 1... Separator, 2... Positive electrode, 3... Negative electrode, 4... Electrode group, 5... Battery can, 6... Electrolyte, 7... Top insulator, 8... Sealing body, 10... Lithium secondary battery, 21... Positive electrode lead, 31 ... Negative electrode lead, 40... Powder processing device, 41, 42, 43... Jig, 100... Laminated body, 110... Positive electrode, 111... Positive electrode active material layer, 112... Positive electrode current collector, 113... External terminal, 120... Negative electrode, 121... Negative electrode active material layer, 122... Negative electrode current collector, 123... External terminal, 130... Solid electrolyte layer, 200... Exterior body, 200a... Opening, 1000... All-solid lithium secondary battery

Claims (10)

Lithium metal composite oxide particles having pores and containing Li and element M;
A positive electrode active material for a lithium secondary battery, which is located in the pore and includes a compound containing Si,
The ratio of the amount of Si to the sum of the amounts of the elements M and Si is greater than 0 mol% and not more than 5.0 mol%,
Ratio of 50% cumulative volume particle size B 50 of the positive electrode active material for lithium secondary batteries after powder compaction treatment at 35 MPa to ₅₀ % cumulative volume particle size A ₅₀ of the positive electrode active material for lithium secondary batteries before compaction treatment A positive electrode active material for a lithium secondary battery, which has a B ₅₀ /A ₅₀ of 0.92-1.00. The ratio of the 10% cumulative volume particle size B of the positive electrode active material for lithium secondary batteries after the powder compacting process to the 10% cumulative volume particle size A ₁₀ of the positive _electrode active material for a lithium secondary battery before the compacting process. The positive electrode active material for a lithium secondary battery according to claim 1, wherein a certain B ₁₀ /A ₁₀ is 0.92-1.00. The ratio of the 90% cumulative volume particle size B _of the positive electrode active material for lithium secondary batteries after the powder compacting process to the 90% cumulative volume particle size A ₉₀ of the positive electrode active material for a lithium secondary battery before the compacting process. The positive electrode active material for a lithium secondary battery according to claim 1 or 2, wherein a certain B ₉₀ /A ₉₀ is 0.94-1.00. The lithium metal composite oxide contains Ni and element X as the element M,
The element X is at least one element selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, B, S, and P. can be,
The lithium secondary battery according to any one of claims 1 to 3, wherein the material ratio of Li, the Ni, and the element X contained in the positive electrode active material for a lithium secondary battery satisfies the following formula (I). Cathode active material for next-generation batteries.
[Li]:[Ni]:[X]=b:(1-a):a (I)
(However, 0.9≦b≦1.2 and 0<a≦0.2) The positive electrode active material for a lithium secondary battery according to any one of claims 1 to 4, wherein the positive electrode active material for a lithium secondary battery has a BET specific surface area of 2.0 m ² /g or less. A positive electrode for a lithium secondary battery, comprising the positive electrode active material for a lithium secondary battery according to any one of claims 1 to 5. A lithium secondary battery comprising the positive electrode for a lithium secondary battery according to claim 6. A step of mixing a metal composite compound containing element M and a solution containing Si to obtain a mixture;
drying the mixture to obtain a Si-containing metal composite compound;
A method for producing a positive electrode active material for a lithium secondary battery, comprising the step of mixing and firing the Si-containing metal composite compound and a lithium compound. In the step of obtaining the mixture, the metal composite compound and the solution containing Si are mixed so that the ratio of the amount of Si to the total amount of the elements M and Si is greater than 0 mol% and less than or equal to 5.0 mol%. The method for producing a positive electrode active material for a lithium secondary battery according to claim 8, which comprises mixing the following. The positive electrode active material for a lithium secondary battery includes Li and a lithium metal composite oxide containing Ni and element X as the element M,
The element X is at least one element selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, B, S, and P. can be,
The positive electrode active material for a lithium secondary battery according to claim 8 or 9, wherein a material ratio of Li, the Ni, and the element X contained in the positive electrode active material for a lithium secondary battery satisfies the following formula (I). A method of manufacturing a substance.
[Li]:[Ni]:[X]=b:(1-a):a (I)
(However, 0.9≦b≦1.2 and 0<a≦0.2)

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