Abstract
The self‐discharge rate of an all‐solid‐state battery having a Li negative electrode, a solid polymeric electrolyte, and a polypyrrole‐polyethylene oxide positive composite electrode was studied under various conditions. Both the self‐discharge rate and the electrochemical utilization of the polypyrrole increase rapidly with temperature. Very little self‐discharge occurs when the charged cell is stored at ambient temperature and heated just before discharge. The self‐discharge reaction is started, only when the Li electrode is attached to the cell, but is not caused by internal short‐circuiting of the cell. The polypyrrole‐based composite electrode itself does not self‐discharge. Indeed, no self‐discharge is observed when the electrode is heated for long periods in contact with the solid polymeric electrolyte, but without contact to the lithium anode. We conclude, therefore, that the self‐discharge reaction is caused by some mobile redox species formed by the reaction of the Li electrode with the solid electrolyte or with impurities in the solid electrolyte.