The effects of tetraethoxysilane (TEOS) as an electrolyte additive on the electrochemical performance of lithium ion batteries with LiMn2O 4 cathode were investigated. With 5% TEOS added, the capacity and cycling performance were improved, not only at room temperature, but also at low temperature, because of the formation of an effective solid electrolyte interphase (SEI) on the LiMn2O4 surface. The results of scanning electron microscopy (SEM) of the LiMn2O4 cathode after the initial charge/discharge cycle proved the existence of this SEI. Fourier transform infrared spectroscopy (FTIR) confirmed the compositions on the interface of the LiMn2O4 cathode. The results showed that this kind of effective organosilicon compound could provide a new promising direction for the development of organic additives to improve the electrochemical performance of lithium-ion batteries.