Effect of Using Fluorinated Ether and Sulfone as Electrolyte Solvents for Lithium Ion Batteries with Lithium-Rich Layered Cathodes and Silicon Oxide Anodes

摘要

We examined fluorinated ether and sulfone as electrolyte solvents for Lithium (Li) ion batteries with Li-rich layered cathodes and Silicon oxide anodes. We evaluated the mixture of cyclic carbonate, sulfone compound, and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropopyl ether (FE1). The gas volume after the initial charge-discharge process increased with the amount of ethylene carbonate (EC) or 4-fluoro 1,3-dioxolane 2-one (FEC). These results show that the reaction between EC or FEC and cathode-active material can be considered to be the cause of gas evolution in the initial charge-discharge cycle. We evaluated sulfone compounds and low-viscosity solvents. By using electrolyte solution with ethyl isopropyl sulfone, FE1, and FEC as electrolyte solvents, the retention capacity after 500 cycles increased to around 67%, which was larger than that of conventional electrolyte solutions such as 1 M LiPF_6 EC/diethyl carbonate (30/70 v/v).