Effect of tris(trimethylsilyl)borate on the high voltage capacity retention of LiNi0.5Co0.2Mn0.3O2/graphite cells

Abstract This study demonstrates that tris(trimethylsilyl)borate (TMSB) additive in the electrolyte can dramatically improve the cycling performance of LiNi 0.5 Co 0.2 Mn 0.3 O 2 /graphite cell at higher voltage operation. And the effects of this additive are characterized by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). In the voltage range of 3.0–4.4 V, LiNi 0.5 Co 0.2 Mn 0.3 O 2 /graphite cell with TMSB in the electrolyte retains about 92.3% of its initial capacity compared to the cell without additive in the electrolyte that retains only 28.5% of its initial capacity after 150 cycles, showing the promising prospect of TMSB at higher voltage. The enhanced cycling performance is attributed to the thinner film originated from TMSB on the LiNi 0.5 Co 0.2 Mn 0.3 O 2 and the combination of TMSB with PF 6 − and F − in the electrolyte, which not only protects the undesirable decomposition of EC solvents but also results in lower interfacial impedance.