Lithium composite metal compound, positive electrode active material for lithium secondary battery, positive electrode for lithium secondary battery, lithium secondary battery, and method for manufacturing lithium composite metal compound

1. A lithium composite metal compound represented by Composition Formula (I),

Li[Li x (Ni (1-y-z) Co y Mn z ) 1-x ]O 2   (I)

where M represents one or more elements selected from the group consisting of Mn, Fe, Cu, Ti, Mg, Al, W, B, Mo, Zn, Sn, Zr, Ga, Nb, and V, and −0.10≤x≤0.2, 0<y≤0.2, 0≤z≤0.2, and 0<y+z≤0.25 are satisfied,

wherein physical property values of pores that are obtained from measurement of nitrogen adsorption and desorption isotherms at a liquid nitrogen temperature satisfy requirements (1) and (2),

(1) a total pore volume determined from an amount of nitrogen adsorbed when a relative pressure (p/p o ) of an adsorption isotherm is 0.99 is 0.008 cm 3 /g or more and 0.012 cm 3 /g or less, and

(2) in a pore distribution determined from a desorption isotherm by a BJH method, a proportion of a volume of pores of 15 nm or less with respect to a total pore volume of 200 nm or less is less than 50%, and

wherein, in the pore distribution determined from the desorption isotherm by the BJH method, a minimum value of pore diameters at which a peak of a log differential pore volume is observed is 20 nm or more.

2. The lithium composite metal compound according to claim 1 ,

wherein a content of lithium carbonate is 0.3 mass % or less, and a content of lithium hydroxide is 0.2 mass % or less.

3. The lithium composite metal compound according to claim 1 ,

wherein, in the pore distribution determined from the desorption isotherm by the BJH method, a minimum value of pore diameters at which a peak of a log differential pore volume is observed is 10 nm or more.

4. The lithium composite metal compound according to claim 1 ,

wherein, in a hysteresis loop of the adsorption isothem and the desorption isotherm that are obtained from the measurement of the nitrogen adsorption and desorption isothems,

in a case where an area between the adsorption isotherm and the desorption isotherm at the relative pressures (p/p o ) in a range of 0.7 or more and 0.9 or less is denoted by S1, and

an area between the adsorption isotherm and the desorption isotherm at the relative pressures (p/p o ) in a range of 0.5 or more and 0.9 or less is denoted by S2, a ratio (S1/S2) of the S1 to the S2 is 0.8 or more.

5. The lithium composite metal compound according to claim 1 ,

wherein, in the pore distribution determined from the desorption isotherm by the BJH method,

a peak of a log differential pore volume is present at a pore diameter in a range of 10 nm or more and 40 nm or less.

6. The lithium composite metal compound according to claim 1 ,

wherein, in the pore distribution determined from the desorption isotherm by the BJH method, a peak value of a log differential pore volume at a pore diameter in a range of 3 nm or more and 5 nm or less is less than 0.005 cm 3 /(g·nm).

7. The lithium composite metal compound according to claim 1 ,

wherein, in the pore distribution determined from the desorption isotherm by the BJH method, a peak value of a log differential pore volume is not present at a pore diameter in a range of 3 nm or more and 5 nm or less.

8. A positive electrode active material for a lithium secondary battery, comprising:

the lithium composite metal compound according to claim 1 .

9. A positive electrode for a lithium secondary battery, comprising:

the positive electrode active material for a lithium secondary battery according to claim 8 .

10. A lithium secondary battery comprising:

the positive electrode for a lithium secondary battery according to claim 9 .

11. A method for manufacturing a lithium composite metal compound represented by Composition Formula (I), the method comprising:

Li[Li x (Ni (1-y-z) Co y Mn z ) 1-x ]O 2   (I)

where M represents one or more elements selected from the group consisting of Mn, Fe, Cu, Ti, Mg, Al, W, B, Mo, Zn, Sn, Zr, Ga, Nb, and V, and −0.10≤x≤0.2, 0<y≤0.2, 0≤z≤0.2, and 0<y+z≤0.25 are satisfied,

a step of calcining a mixture of a lithium compound and a transition metal compound to obtain a lithium composite metal compound;

a water washing step of removing the lithium compound remaining in the lithium composite metal compound by water washing; and

a step of drying the water-washed lithium composite metal compound,

wherein the drying step is performed in a rotary kiln supplied with a gas having a carbon dioxide concentration of 300 ppm or less, the water-washed lithium composite metal compound is heated at a temperature of 150° C. or higher and 300° C. or lower in the rotary kiln, and a ratio (B/A) of an aeration rate B (Nm 3 /hour) of a gas that is supplied from an outside to a moisture evaporation rate A (kg/hour) during drying is 2 Nm 3 /kg or more and 20 Nm 3 /kg or less, and

wherein, the aeration rate B is the aeration rate of the gas with a carbon dioxide concentration of 300 ppm or less.