Rational Electrolyte Design for Interfacial Chemistry Modulation to Enable Long‐Term Cycling Si Anode

Abstract The silicon anode is promising for high‐energy density lithium‐ion batteries owing to its ultrahigh theoretical capacity. However, the practical deployment of Si anodes is significantly hindered by its large volume change and unstable electrode/electrolyte interphase associated with routine electrolytes. Herein, a cyclic ether‐based electrolyte is designed and shows high compatibility with Si anodes. By simply decreasing the prevalence of ethereal oxygen groups and increasing the degree of molecule unsaturation of 1,2‐dimethoxyethane simultaneously, the resulting cyclic tetrahydrofuran (THF) presents a weak solvation capability and strong polymerization. Experimental and computational evidence demonstrates this rational design leads to a remarkable improvement in electrochemical performance of Si anodes. By forming a thin, elastic, and LiF‐rich inorganic‐polymeric solid‐electrolyte interphase film, the Si electrode cycled in THF‐based electrolyte exhibits long‐term cycling stability with a high reversible capacity of 1995.7 mAh g −1 after 400 cycles. The full‐cells with Si/graphite anodes and LiFePO 4 cathodes maintain over 80% capacity retention after 600 cycles.