Abstract In this work, trimethylboroxine is used as electrolyte additive to improve the electrode/electrolyte interface stability of LiNi1/3Co1/3Mn1/3O2 (LNCM) cathode for high voltage lithium ion battery. Charge/discharge tests show that addition of 3% TMB is the optimal amount for LNCM. After 300 cycled at 1C rate under the cut-off charge voltage of 4.5 V, the LNCM with 3% TMB achieves a capacity retention of 99%, compared to the 40% of that using STD electrolyte (1 M LiPF6 in ethylene carbonate/diethyl carbonate /dimethyl carbonate). The results from LSV, EIS and physical characterizations, including SEM, TEM, XPS and ICP–MS, demonstrate that TMB oxidizes preferentially to the STD electrolyte, and catalyzes the decomposition of base electrolyte subsequently, generating a thin and low impedance film on the LNCM surface, which effectively stabilizes the electrode/electrolyte interface by suppressing the continuous oxidation of STD electrolyte and the dissolution of LNCM, and hence, improves the cyclic and rate performances of LNCM under high voltage.