LITHIUM SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To enhance discharging capacity and cyclic characteristics of a lithium secondary battery is charging and discharging at 4 V or less at which drop in battery lifetime resulting from decomposition of the electrolytic solution is unlikely, compared with non-substituted iron phosphate lithium. SOLUTION: The lithium secondary battery using a positive electrode consisting of lithium iron phosphate series material available at a low cost and capable of charging and discharging at 4 V or less is equipped with an increased discharging capacity with a practical current. The positive electrode active material 5 consists of a substance as phosphoric acid compound of olivin structure expressed by zFe1-yXyPO4(0