Trimethoxymethylsilane as a solid-electrolyte interphases improver for graphite anode

To improve the cycling performance of graphite anode materials, we propose a functional electrolyte additive, trimethoxymethylsilane (TMSi), which contains a silyl ether functional group as part of its molecular structure. First principal calculation studies, in addition to ex situ analyses, demonstrated that electrochemical reduction of ethylene carbonate (EC) gives an anionic reduced EC product. Subsequent chemical reaction with TMSi then generates solid-electrolyte interphase (SEI) layers of Si–O and Si–C functionalized carbonate on the surface of the graphite anode, which prolongs and stabilizes the cycling performance of the cells. As a result, the cell cycled with TMSi-controlled electrolyte exhibits a cycling retention of 89.5%, whereas the cell cycled with standard electrolyte suffers from poor cycling retention (84.3%) after 100 cycles. [Display omitted] •Trimethoxymethylsilane is proposed to improve cycling retention of graphite anode.•Mechanism for formation of SEI layers is clarified by first principal calculation.•Silyl ether-functionalized SEI layers improve surface stability of graphite.•The cell cycled with trimethoxymethylsilane exhibits improved cycling retention.•Electrolyte decomposition is well suppressed on the surface of graphite.