Mechanisms for electrochemical performance enhancement by the salt type electrolyte additive, Vinyltriethoxysilane, in high-voltage lithium-ion batteries

Lithium-ion batteries (LIBs) have attracted attention due to their potential to facilitate the rapid development of mobile electronic devices, electronic vehicles and energy storage. However, the high flammability of carbonate-based electrolytes has long been one of the most important obstacles for the further applications of these types of batteries. To develop safer advanced batteries, herein we use an environmentally-friendly additive, vinyltriethoxysilane (VTES), to suppress the flammability of a carbonatebased electrolyte. VTES was found to not only reduce the flammability of the electrolyte, but also enhance the thermal stability of both the electrolyte and the LiCoO2 cathode by forming a stable surface layer. In order to gain insight into the reaction process of the electrolyte with VTES, we used density functional theory to elucidate their formation mechanism. The results indicate that the vinylsilyl radical tends to preferably react with the oxygen atoms of solvent molecules to form more stable compounds. These results show that VTES is a promising additive to improve the safety of LIBs.