A Theoretical Study of Growth of Solid-Electrolyte-Interphase Films in Lithium-Ion Batteries with Organosilicon Compounds

Abstract

We attempt to reveal how electrolyte additives affect the structural evolution of the solid electrolyte interphase (SEI) film on the anode surface of a lithium-ion secondary battery. Employing the hybrid Monte-Carlo/molecular-dynamics method, we theoretically investigate the SEI film structures in organic liquid-electrolyte systems with and without an organosilicon additive. The results show that the excessive growth of the SEI film is suppressed by introducing the organosilicon additives. It is further elucidated that the decomposition products of the organosilicon molecules are stably aggregated in the vicinity of the anode surface, and protect the electrolyte solvents and the lithium salts from the further reductive decomposition. These findings imply that the organosilicon additive possibly improves the cycle performance of LIBs owing to the formation of the effective SEI film.