Improved solid electrolyte interphase and Li-storage performance of Si/graphite anode with ethylene sulfate as electrolyte additive

Abstract

Silicon/graphite composite anodes have drawn extensive attention in the field of power Li-ion batteries for application in electric vehicles because of their much higher capacity than that of traditional graphite anodes. In this work, ethylene sulfate (1,3,2-dioxathiolane-2,2-dioxide, DTD) is investigated as an electrolyte additive to improve the Li-storage performance of silicon/graphite composite anode. The electrochemical behavior of silicon/graphite anode including cyclic voltammogram, discharge/charge performance at various current density and during long-term cycling, and electrochemical impedance is systematically studied by adding different amounts of DTD into electrolyte. The effects of DTD on the solid/electrolyte interphase (SEI) film are analyzed through scanning electron microscopy, X-ray photoelectron and Fourier transform infrared spectroscopy. It is found that DTD participates into the film-formation process through its reductive decomposition reactions on electrode surface, producing a thin, uniform and stable SEI. The Li-storage performance of silicon/graphite anode is improved at an optimized addition amount of DTD.