Fluorine- and maleimide-functionalized electrolyte additive as an interface modifier for Ni-rich LNMC/SiOx batteries

Abstract

SiOx anodes and Ni-rich LiNixCoyMnzO2 (LNMC) cathodes are considered practical electrodes for electric vehicles; however, these advanced electrode materials suffer from poor prolonged cycling. In this study, N-(4-fluorophenyl)maleimide (FPMI) is used as an electrolyte additive that simultaneously enhances the interfacial stability of each electrode through the formation of solid electrolyte interphase (SEI) or cathode electrolyte interphase (CEI) layers. The electrochemical reduction and oxidation of FPMI promote the formation of SEI and CEI layers on the SiOx anode and Ni-rich LNMC cathode, respectively. FPMI addition also considerably increases the cycling retention because the FPMI-derived SEI and CEI layers effectively inhibit electrolyte decomposition during cycling, thereby increasing the cell lifespan. Additional spectroscopic analyses indicate that the SEI and CEI layers developed on each electrode effectively prevent parasitic reactions, such as electrolyte decomposition with transition metal dissolution in the cell; thus, the surface stability of the cell is also improved.