NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To stop heat generation so as to prevent thermorunaway even if overcharge or an internal short-circuit occurs by covering a part or the entire part of the surface of a lithium containing metal oxide with a metal and/or carbon material mixture layer having a dissolving potential larger by a certain potential than that of lithium, and by setting the specific resistance of a positive electrode mixture layer to a specific value or less. SOLUTION: In order to restrain the interaction of a lithium containing metal oxide with a solvent of a nonaqueous electrolyte in an overcharge and an internal short circuit, a part or the entire part of the surface of the lithium containing metal oxide is covered with a metal and/or carbon material mixture layer having a dissolving potential larger by three or more volts than that of lithium. Thereby, a heat generation rate is restrained by forming an electrolyte diffusion barrier between the lithium containing metal oxide surface layer and a bulk electrolyte layer. The increase of contact resistance in conjunction with the expansion and contraction of the lithium containing metal oxide is restrained by covering it with the metal and/or carbon material mixture layer and by setting the specific resistance of a depolarizing mixture layer to 1 Ωm or less.