Pre‐Constructed Mechano‐Electrochemical Adaptive Solid Electrolyte Interphase to Enhance Li + Diffusion Kinetics and Interface Stability for Chemically Prelithiated SiO Anodes

Abstract The development of silicon monoxide (SiO) anode in high‐energy lithium‐ion batteries (LIBs) is challenged by low initial Coulombic efficiency (ICE) and significant volume expansion. Although chemical prelithiation can enhance the ICE of SiO, it inevitably induces volume expansion in advance and suffers the inferior air stability. Herein, a chemical prelithiation‐mediated strategy is proposed that pre‐constructs a mechano‐electrochemical adaptive solid electrolyte interphase (SEI) through the spontaneous reaction of ammonium hexafluorozirconate (Ah) with the chemically prelithiated SiO anode (Pr‐SiO). The mechano‐electrochemical adaptive SEI, enriched with LiF, Li 3 N, and ZrO 2 components, exhibits a unique structure of “rigid inside and flexible outside” to enhance electrochemical reaction kinetics and mechanical durability. The Pr‐SiO with the adaptive SEI (Ah‐Pr‐SiO) possesses high ICE (99.4%), fast Li + diffusion kinetics, and superior cycle stability (1435.8 mAh g −1 after 200 cycles). Notably, the designed Ah‐Pr‐SiO reveals high hydrophobicity and air stability, leading to feasible industrial compatibility. The assembled pouch cell (LiNi 0.8 Co 0.1 Mn 0.1 O 2 //Ah‐Pr‐SiO) exhibits stable cycling with a high energy density (346.6 Wh kg −1 ). This work provides a novel chemical prelithiation‐mediated pre‐constructed SEI strategy, offering the possibility of designing an advanced SEI for Si‐based anodes toward high energy density long‐life lithium‐ion batteries.