SECONDARY BATTERY AND METHOD FOR PRODUCING SAME

This invention provides a secondary battery that comprises a positive electrode comprising a positive electrode active material, a negative electrode comprising a negative electrode active material, and a non-aqueous electrolyte comprising a supporting salt. The positive electrode active material is a manganese phosphate compound represented by the next general formula: NaMnPOF. Herein, x satisfies 2.02 < x ≤ 2.50. Mn may be partially substituted with one, two or more species of metal selected from Al, Mg and Ti.