POSITIVE ELECTRODE FOR LITHIUM-ION SECONDARY BATTERY AND LITHIUM-ION SECONDARY BATTERY
A positive electrode for a lithium-ion secondary battery of the present invention includes a collector for a positive electrode and a positive electrode active material layer provided on the collector for a positive electrode. The positive electrode active material layer includes a positive electrode active material, a conductive auxiliary agent, and a binder, the conductive auxiliary agent includes flake-shaped graphite having an average thickness of 0.5 μm or less, and, when an average particle diameter of the positive electrode active material is represented by D 50 , the average particle diameter of the flake-shaped graphite is equal to or more than (3× active material D 50 /5) and equal to or less than (9× active material D 50 /10).
1 . A positive electrode for a lithium-ion secondary battery, comprising:
a collector for a positive electrode; and
a positive electrode active material layer provided on the collector for a positive electrode,
wherein the positive electrode active material layer includes a positive electrode active material, a conductive auxiliary agent, and a binder,
the conductive auxiliary agent includes flake-shaped graphite having an average thickness of 0.5 μm or less, and
when an average particle diameter of the positive electrode active material is represented by active material D 50 , the average particle diameter of the flake-shaped graphite is equal to or more than (3× active material D 50 /5) and equal to or less than (9× active material D 50 /10).
2 . The positive electrode for a lithium-ion secondary battery according to claim 1 ,
wherein the conductive auxiliary agent further includes carbon black having an average particle diameter of primary particles being equal to or more than 5 nm and equal to or less than 500 nm.
3 . The positive electrode for a lithium-ion secondary battery according to claim 1 ,
wherein the positive electrode active material includes a lithium complex oxide.
4 . The positive electrode for a lithium-ion secondary battery according to claim 3 ,
wherein the lithium complex oxide includes a lithium nickel complex oxide having a lamellar crystal structure.
5 . The positive electrode for a lithium-ion secondary battery according to claim 3 ,
wherein the lithium complex oxide includes a compound represented by Formula (1),
Li a Ni 1-x M x O 2 (1)
(in the formula, M represents at least one selected from Li, Co, Mn, Mg, and Al, 0<a≤1, 0<x<0.7).
6 . The positive electrode for a lithium-ion secondary battery according to claim 1 ,
wherein a density of the positive electrode active material layer is equal to or more than 3.30 g/cm 3 .
7 . The positive electrode for a lithium-ion secondary battery according to claim 1 ,
wherein an average particle diameter (D 50 ) of the positive electrode active material is equal to or more than 0.5 μm and equal to or less than 20 μm.
8 . A lithium-ion secondary battery comprising:
the positive electrode for a lithium-ion secondary battery according to claim 1 ;
a negative electrode; and
a non-aqueous electrolytic solution.