PURPOSE: To decrease deterioration of high molecular compound used as electrode and increase charge-discharge cycle life by charging a secondary battery using a high molecular compound having conjugated double bond in its principal chain at constant current in the first half and at constant voltage in the latter half.
CONSTITUTION: When a secondary battery using a high molecular compound having conjugated double bond in its principal chain, or electroconductive high molecular compound obtained by doping dopant to the above compound as electrode active material is charged, voltage increasing ratio in the initial constant current charging is differentiated twice, and when differenciated value becomes zero, charging is switched to constant voltage. By this charging, side reaction or decomposition of electrolyte, or decomposition of conjugated double bond of the polymer caused by active decomposition product of solvent in electrolyte, which usually occur during charging, is suppressed, and charge-discharge cycle life is increased.
FUJITA KAZUNORI
SUGIMOTO HIROYUKI
KOBAYASHI MASAO
SAWADA YOSHIMITSU
SHOWA DENKO KK