Mild Chemical Lithiation Strategy for Achieving Synergistic Lithium‐Compensation and Carbon‐Coating on SiO Anodes

Abstract Silicon monoxide (SiO_x, x ≈ 1) has emerged as a promising anode material for next‐generation lithium‐ion batteries (LIBs) due to its high theoretical capacity. However, its commercial viability is hindered by low initial Coulombic efficiency (ICE) and insufficient cycling stability. Herein, a mild chemical lithiation strategy is proposed that synergistically integrates lithium‐compensation and carbon‐coating to address these challenges, significantly boosting the electrochemical performance of SiO anode. Biphenyl‐lithium/2‐methyltetrahydrofuran (Bp‐Li/2‐MeTHF) is elaborately selected as a dual‐functional chemical lithiation reagent to ensure sufficient lithium incorporation into SiO at room temperature and simultaneously biphenyl (Bp^*−) radical in‐situ polymerizes, then is converted into a carbon shell on a silicon/lithium silicates core upon subsequent thermal annealing (Li‐SiO@C). This unique structure of Li‐SiO@C effectively compensates for irreversible lithium loss and buffers volume expansion, leading to an exceptional ICE of 91.0% and remarkable capacity retention of 92.2% after 500 cycles, far surpassing the 72.9% ICE and 9.0% retention observed in the pristine SiO anode. Moreover, Li‐SiO@C demonstrates excellent moisture resistance that is well suited for aqueous‐based electrode coating processes. This work presents a simple yet effective strategy to enhance the electrochemical performance of SiO anodes, offering strong potential for large‐scale applications in high‐energy‐density LIBs.