Investigation of lead tin fluorides as possible negative electrodes for Li-ion batteries

Lead fin fluorides are well known fast ion conductors. In this study the el ectrochemical behaviour of materials as negative electrodes in lithium rech argeable batteries was investigated. The initial reduction with lithium occ urs at much higher potentials for fluorides than oxides. This correlates we ll with the standard energies of formation of metals and Lithium oxide/fluo ride on lithium insertion. Lead rich compounds present a greater degree of crystallinity than tin rich materials; and it is also observed that fluorid e matrices exhibit greater crystallinity after cycling than their oxide cou nterparts. Tin oxide exhibits the best cycling performance and this seems t o correlate with the low degree of crystallinity observed in this system. ( C) 2001 Elsevier Science B.V. All rights reserved.