Breaking Kinetic Barriers in Silicon Anodes via Strategic Electrolyte Additive Engineering

Abstract The silicon anode is one of the primary contenders for lithium‐ion batteries of higher energy density owing to its outstanding theoretical capacity. However, the native SiO₂ layer (2–5 nm) on commercial silicon nanoparticles severely limits ion transport and induces polarization, especially under high current densities. This study systematically examines the influence of SiO₂ layer thickness on silicon anode performance, identifying significant polarization as the main barrier to stable cycling. To tackle this, a strategic electrolyte additive is suggested, bis(trimethylsilyl)trifluoroacetamide (BTA), which mitigates these effects by scavenging inactive SiO₂ and promoting the formation of conductive Li_xSiO_y intermediates. Experimental and computational results show that BTA dramatically reduces electrochemical polarization and enhances Li⁺ transport, leading to superior cyclic stability. The Si anode with BTA‐modified electrolyte maintains 1436.5 mAh g⁻¹ after 120 cycles at 500 mA g⁻¹—substantially outperforming the base electrolyte (894.5 mAh g⁻¹). This work highlights a critical strategy for overcoming kinetic barriers and advancing silicon anodes toward practical, high‐density energy applications.