Protecting Li/TiS2 Cells Against Overcharge

New electrolyte additive, N,N,N',N'- tetramethyl-1,4-phenylenediamine (TMPD), helps protect lithium/titanium disulfide rechargeable cells against overcharge. TMPD is redox couple: during overcharge, it undergoes electrochemical reactions at both electrodes and takes up excess input charge. Without TMPD, overcharge results in oxidative degradation of nonaqueous electrolyte, leading to loss of rechargeability and safety problems. Li/TiS2 cells currently being considered for spacecraft and military applications.