HIGH-VOLTAGE CHARGE TYPE NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

摘要

Storage performance, initial capacitance and cycle characteristics are improved in a nonaqueous electrolyte secondary battery which is used after being charged to a high potential. Specifically disclosed is a nonaqueous electrolyte secondary battery comprising a positive electrode added with lithium phosphate and containing a positive electrode active material which contains a lithium cobalt complex oxide wherein at least zirconium and magnesium are added to LiCoO₂ and a lithium manganese nickel complex oxide having a lamellar structure, a negative electrode containing a negative electrode active material, and a nonaqueous electrolyte containing a nonaqueous solvent and an electrolyte salt. In this nonaqueous electrolyte secondary battery, the positive electrode has a potential base on lithium of higher than 4.3 V but not higher than 5.1 V, and the nonaqueous electrolyte contains vinylene carbonate as the nonaqueous solvent and not less than 0.1 M but not more than 0.5 M of at least one of lithium bispentafluoroethane sulfonylimide and lithium bistrifluoromethane sulfonylimide as the electrolyte salt, while being added with 1,3-dioxane.