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 LixSiOy 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.