Enhanced high-temperature cycle life of LiFePO4-based Li-ion batteries by vinylene carbonate as electrolyte additive

Addition of vinylene carbonate (VC) in electrolyte solution has been found to greatly improve the high-temperature (55 degrees C) cycling performance of LiFePO4-based Li-ion batteries. It has been established that the VC additive remarkably suppresses Fe dissolution from LiFePO4 cathode and hence, subsequent Fe deposition on the anode side. Furthermore, the VC additive also significantly reduces formation of solid-electrolyte interface layers on both LiFePO4 cathodes and mesocarbon microbead (MCMB) anodes. With VC addition, a 18650-type LiFePO4/MCMB cell has been shown to retain similar to 80% capacity after 980 cycles at 55 degrees C under 1-3 C charge-discharge rates. This is in contrast with more than 25% capacity loss after merely 100 cycles when no VC is added. (c) 2006 The Electrochemical Society.