CATHODE ACTIVE MATERIAL POWDER FOR LITHIUM SECONDARY BATTERY, ELECTRODE, AND SOLID LITHIUM SECONDARY BATTERY
A cathode active material powder for lithium secondary batteries is provided, containing a core particle consisting of a lithium metal composite oxide, and a coating layer coating at least a part of the core particle, in which the coating layer contains an oxide containing at least one element A selected from the group consisting of Nb, Ta, Ti, Al, B, P, W, Zr, La, and Ge, and the following (1) and (2) are satisfied. (1) a substance amount of the element A per unit area, which is calculated from analysis results by inductively coupled plasma mass spectrometry and a nitrogen adsorption BET method, is 3.0×10 −4 mol/m 2 or less, and (2) a standard deviation of a compositional ratio of the element A, which is calculated from a value obtained from an SEM-EDX analysis result, is 4.6 or more and 8.2 or less.
1 . A cathode active material powder for lithium secondary batteries, comprising:
a core particle consisting of a lithium metal composite oxide; and
a coating layer coating at least a part of the core particle,
wherein the coating layer contains an oxide containing at least one element A selected from the group consisting of Nb, Ta, Ti, Al, B, P, W, Zr, La, and Ge, and
the following (1) and (2) are satisfied,
(1) a substance amount of the element A per unit area, which is calculated from analysis results by inductively coupled plasma mass spectrometry and a nitrogen adsorption BET method, is 3.0×10 −4 mol/m 2 or less, and
(2) a standard deviation of a compositional ratio of the element A to a total number of atoms in the cathode active material powder for lithium secondary batteries, which is calculated from a value obtained from an SEM-EDX analysis result, is 4.6 or more and 8.2 or less.
2 . The cathode active material powder for lithium secondary batteries according to claim 1 ,
wherein the cathode active material powder is used by being brought into contact with a solid electrolyte.
3 . The cathode active material powder for lithium secondary batteries according to claim 2 ,
wherein the cathode active material powder is used in a solid lithium secondary battery containing a sulfide solid electrolyte.
4 . The cathode active material powder for lithium secondary batteries according to claim 1 ,
wherein a surface presence rate of the element A, which is calculated from an XPS analysis result of the cathode active material powder for lithium secondary batteries, is 50% or more.
5 . The cathode active material powder for lithium secondary batteries according to claim 1 ,
wherein the element A is Nb or P.
6 . The cathode active material powder for lithium secondary batteries according to claim 1 ,
wherein the cathode active material powder has a layered crystal structure.
7 . The cathode active material powder for lithium secondary batteries according to claim 1 ,
wherein the following compositional formula (I) is satisfied,
Li[Li x (Ni (1−y−z−w) Co y Mn z M w ) 1−x ]O 2 (I)
(where, M is at least one element selected from the group consisting of Fe, Cu, Mg, Al, W, B, P, Mo, Zn, Sn, Zr, Ga, La, Ti, Nb, and V, and −0.10≤x≤0.30, 0≤y≤0.40, 0≤z≤0.40, and 0<w≤0.10 are satisfied).
8 . The cathode active material powder for lithium secondary batteries according to claim 7 ,
wherein, in the compositional formula (I), 0.50≤1−y−z−w≤0.95 and 0<y≤0.30 are satisfied.
9 . An electrode comprising:
the cathode active material powder for lithium secondary batteries according to claim 1 .
10 . The electrode according to claim 9 , further comprising:
a solid electrolyte.
11 . A solid lithium secondary battery, comprising:
a cathode;
an anode; and
a solid electrolyte layer interposed between the cathode and the anode,
wherein the solid electrolyte layer contains a first solid electrolyte,
the cathode includes a cathode active material layer in contact with the solid electrolyte layer, and a current collector on which the cathode active material layer is laminated, and
the cathode active material layer contains the cathode active material powder for lithium secondary batteries according to claim 1 .
12 . The solid lithium secondary battery according to claim 11 ,
wherein the cathode active material layer further contains a second solid electrolyte.
13 . The solid lithium secondary battery according to claim 12 ,
wherein the first solid electrolyte and the second solid electrolyte are the same material.
14 . The solid lithium secondary battery according to claim 11 ,
wherein the first solid electrolyte is a sulfide solid electrolyte.
15 . The cathode active material powder for lithium secondary batteries according to claim 2 ,
wherein a surface presence rate of the element A, which is calculated from an XPS analysis result of the cathode active material powder for lithium secondary batteries, is 50% or more.
16 . The cathode active material powder for lithium secondary batteries according to claim 2 ,
wherein the element A is Nb or P.
17 . The cathode active material powder for lithium secondary batteries according to claim 2 ,
wherein the cathode active material powder has a layered crystal structure.
18 . The cathode active material powder for lithium secondary batteries according to claim 2 ,
wherein the following compositional formula (I) is satisfied,
Li[Li x (Ni (1−y−z−w) Co y Mn z M w ) 1−x ]O 2 (I)
(where, M is at least one element selected from the group consisting of Fe, Cu, Mg, Al, W, B, P, Mo, Zn, Sn, Zr, Ga, La, Ti, Nb, and V, and −0.10≤x≤0.30, 0≤y≤0.40, 0≤z≤0.40, and 0<w≤0.10 are satisfied).
19 . An electrode comprising:
the cathode active material powder for lithium secondary batteries according to claim 2 .
20 . The solid lithium secondary battery according to claim 12 ,
wherein the first solid electrolyte is a sulfide solid electrolyte.