A Solvent-Regulated Ball-Milling Strategy for Achieving Controllable Silicon Surface Oxidation and Enhanced Stability of Silicon Anodes

To achieve high-performance and cost-effective wet ball-milled silicon, it is crucial to control nanoparticle oxidation during milling. This study introduces a hybrid-solvent-assisted ball-milling approach, utilizing cyclohexane as a nonpolar medium to preserve silicon's integrity during milling and anhydrous ethanol as a polar solvent to induce surface oxidation. The ethanol concentration in the mixed solvent is systematically tuned to regulate surface SiOx and Si-OH/Si-OCH₂CH₃ groups. Furthermore, the impact of ethanol content on the milling efficiency, surface chemistry, structural evolution, and electrochemical performance of the ball-milled silicon is thoroughly evaluated. Notably, the electrode prepared using a mixed solvent containing 10% ethanol (Si-60hy10) retains a capacity of 2216.0 mAh g^-1 after 100 cycles at 0.5 A g^-1, corresponding to 74.88% of its second-cycle capacity. At 1 A g^-1, it still retains 1432.7 mAh g^-1 after 300 cycles (54.93% retention), significantly outperforming silicon prepared via pure-ethanol ball milling (247.0 mAh g^-1). Remarkably, a specific capacity exceeding 1163.3 mAh g^-1 is retained after 1000 cycles at 4 A g^-1. In addition, the LiFePO₄||Si-60hy10 full cell delivers 131.4 mAh g^-1 after 60 cycles (97.19% retention) at 0.5 C, indicating its promising practical applicability. This hybrid solvent ball-milling strategy provides an effective route toward high-performance silicon anodes for lithium-ion batteries.