Stable LiF-rich solid electrolyte interphase via self-polymerizing gel electrolytes boosts silicon anode cycling

Silicon is regarded as the most promising candidate for replacing graphite anodes due to its high theoretical capacity (3579 mAh g −1 ) and favorable operating potential (0.3 V vs. Li + /Li), compatible with practical lithium-ion battery applications. However, the inability of liquid electrolytes to accommodate the severe volume changes of microsized silicon (μSi) particles leads to continuous mechanical stress and unstable solid electrolyte interphase (SEI) formation, resulting in rapid electrode fracture. Herein, we design a self-poymerizing gel electrolyte that utilizes the thermal decomposition of LiPF 6 to simultaneously construct a durable, LiF-rich SEI and initiate ring-opening polymerization of tetrahydrofuran (THF) into a polytetrahydrofuran (PTHF) network. Dynamic cross-linking of the PTHF matrix via reversible hydrogen bonding and coordination interactions provides structural adaptability and introduces a solvent nanoconfinement effect. The optimized μSi||Li half-cell delivers a high capacity of 2936.3 mAh g −1 at 0.1 C and maintains a high capacity of 1171.6 mAh g −1 after 600 cycles at 2 C (where 1 C = 3579 mAh g −1 ), outperforming its countertparts employing liquid electrolytes. This work successfully integrates microsized silicon anodes with adaptive gel electrolytes, offering a promising avenue toward high-performance lithium-ion batteries.