Nonaqueous electrolyte secondary cell and method for charging same

摘要

The invention provides a non-aqueous electrolyte secondary cell that has high capacity and excels in cycle characteristics. The non-aqueous electrolyte secondary cell functions stably at a high potential of from 4.4 to 4.6 V with respect to lithium and inhibits the decomposition of the electrolytic solution at high potential. This is accomplished as follows. The non-aqueous electrolyte secondary cell has a positive electrode having a positive electrode active material; a negative electrode having a negative electrode active material; and a non-aqueous electrolyte having a non-aqueous solvent and electrolytic salt. The positive electrode active material has: lithium cobalt compound oxide having added therein at least zirconium and magnesium; and lithium-nickel-manganese compound oxide having a layered structure. The positive electrode active material has a potential of from 4.4 to 4.6 V with respect to lithium. The non-aqueous solvent contains diethyl carbonate of 10 vol. % or higher at 25° C.