ELECTROCHEMICAL AND X-RAY PHOTOSPECTROSCOPY STUDIES OF POLYTETRAFLUOROETHYLENE AND POLYVINYLIDENE FLUORIDE IN LI C BATTERIES/

The stability of polytetrafluoroethylene (PTFE) and polyvinylidene flu oride (PVDF) used as the anode binders in lithium-ion batteries was st udied by electrochemical and X-ray photospectroscopy (XPS) measurement s. The characteristic discharge/charge curves for PTFE and PVDF were o btained. It is shown that the behavior of PTFE and PVDF exhibits much discrepancy when they are attacked by high active lithium ion in elect rochemical cells. PTFE reacts with lithium easily and decomposes durin g the first discharge process, which is indicated by a long plateau ap pearing around 1.2 V in the first discharge curve of Li/Ni(PTFE) cell. XPS results show that PTFE decomposes after one discharge/charge cycl e, PVDF is rather stable due to a possible surface passivation process . (C) 1997 Elsevier Science S.A.