Fluorophenyl methyl sulfone as an interface modifier for Ni-rich cathode materials of lithium-ion batteries

Abstract

Nickel-rich lithium layered oxides are considered as the most addressing advanced cathode material for lithium-ion batteries, however, its low cycling performance at high temperature is considered the main bottleneck in expanding application areas. To improve poor surface stability of advanced cathode materials, fluorophenyl methyl sulfone is suggested as a surface modifier, which can make stable cathode-electrolyte interphases on the cathode via simple electrochemical oxidation. Electrochemical voltage spectroscopy indicates that the cell cycled with fluorophenyl methyl sulfone exhibits a higher amount of oxidation peaks corresponded to the formation of artificial interphases. In the cycling performance, the cell cycled with fluorophenyl methyl sulfone reveals improved cycling retention (81.7%) compared to that cycled with standard electrolyte (62.5%) at high temperature. Additional systematic analyses suggest that parasitic reaction associated with electrolyte decomposition is well suppressed in the cell controlled with fluorophenyl methyl sulfone because sulfone moiety of the additive participates to effective artificial interphases on the cathode.