Enhancement of low-temperature performance of LiFePO4 electrode by butyl sultone as electrolyte additive

Low-temperature performance of a LiFePO4 electrode is successfully and easily improved by adding butyl sultone (BS) in 1 mol L− 1 LiPF6-ethylene carbonate (EC)/propylene carbonate (PC)/ethyl methyl carbonate (EMC) (1:1:3 vol.%) electrolyte. Through BS addition, discharge capacity and rate performance at low temperature are obviously enhanced. The surface morphology and chemical composition of the solid electrolyte interphase (SEI) formed on the surface of the LiFePO4 electrode are studied through scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis, and combined with the electrochemical impedance spectrum (EIS) analysis, the improved low-temperature performance is attributed to participating in the formation of a thinner SEI film, which enhances the ion conductivity of the SEI film and accelerates the migration of lithium ions through the SEI film.