Patent ID: 7803485

Claim:
A positive electrode, for use in a lithium secondary battery, comprising a positive electrode current collector, and a positive electrode film which is carried on the positive electrode current collector and includes a plurality of mixture layers, wherein the positive electrode film contains, as a positive electrode active material, two or more kinds of lithium-containing compounds having exothermic initiation temperatures different from each other, at least one kind of the two or more kinds of lithium-containing compounds has the exothermic initiation temperature of 300° C. or higher, a first mixture layer of the plural mixture layers, closest to the positive electrode current collector, contains at least one kind of the lithium-containing compound having the exothermic initiation temperature of 300° C. or higher, and said one kind of lithium-containing compound having the exothermic initiation temperature of 300° C. or higher contained in the first mixture layer is a lithium nickel manganese cobalt oxide represented by the chemical formula Li a Ni 1−(b+c) Mn b Co c O 2 where a, b, and c satisfy 1 ≦a ≦1.2, 0.1 ≦b ≦0.5,and 0.1 ≦c ≦0.5, in the first mixture layer, the lithium-containing compound having the exothermic initiation temperature of 300° C. or higher and the lithium-containing compound other than the lithium-containing compound having the exothermic initiation temperature of 300° C. or higher are contained, and a content of the lithium-containing compound having the exothermic initiation temperature of 300° C. or higher is larger than a content of the lithium-containing compound other than the lithium-containing compound having the exothermic initiation temperature of 300° C. or higher, and in an outer mixture layer, the lithium-containing compound having the exothermic initiation temperature of 300° C. or higher and the lithium-containing compound other than the lithium-containing compound having the exothermic initiation temperature of 300° C. or higher are contained, and a content of the lithium-containing compound other than the lithium-containing compound having the exothermic initiation temperature of 300° C. or higher is larger than a content of the lithium-containing compound having the exothermic initiation temperature of 300° C. or higher.