In order to overcome severe capacity fading of LiMn2O4 cathode lithium-ion battery, tris(trimethylsilyl) borate (TMSB) is used as an electrolyte additive. With 0.5 wt% TMSB addition into the electrolyte (EC/DMC with 1 M LiPF6), the capacity retention is significantly improved at both room temperature and 55 °C. The effects of the TMSB on the LiMn2O4 electrode are investigated via a combination of cyclability, capacity retention of high temperature storage, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Based on these results, it is suggested that the improved cyclability of the cells containing the TMSB additive is mainly originated from the participation in the formation of solid electrolyte interface (SEI) on the surface of electrode, the dissolution of LiF out of the SEI and the enhancement of cyclability of Li anode.