High‐Performance Silicon Anodes Enabled by Multifunctional Ultrafine Silica Nanoparticle‐Embedded Carbon Coatings for Lithium‐Ion Batteries

In this study, a high-performance Si-based composite anode by introducing a novel multifunctional coating integrating embedding and buffer structures achieved by embedding ultrafine SiO₂ nanoparticles (<7 nm) within a carbon matrix on Si nanoparticles is reported, yielding a high initial Coulombic efficiency, superior rate and cycling performance.

Abstract

Silicon (Si) holds immense promise as viable anode for next-generation high-energy-density Li-ion batteries (LIBs). However, its poor ionic/electronic conductivity and significant volumetric changes during cycling lead to rapidly deteriorated LIB performance. Here, a novel multifunctional coating featuring ultrafine SiO₂ nanoparticles (<7 nm) embedded carbon on Si nanoparticles (termed Si@uSiO₂-C) to resolve these challenges is proposed. This unique uSiO₂-C coating provides high-efficient electron and ion transport pathways, while also improves interfacial stability and mitigates volume changes during cycling, thereby enhancing the conductivity and structural integrity of Si@uSiO₂-C, as corroborated by extensive experimental and computational studies. In addition, the abundant interfaces in uSiO₂-C coating facilitate Li⁺ transport and the evenly distributed ultrafine SiO₂ nanoparticles impart high electrochemical reactivity and mechanical robustness. Consequently, the Si@uSiO₂-C anode achieves a high reversible capacity of 2093 mAh g⁻¹ at 0.2 A g⁻¹, with a high initial Coulombic efficiency of 88.3%, superior rate capability and durability (1000 cycles, 928 mAh g⁻¹ at 1.0 A g⁻¹, 75% capacity retention). Full cells paired with commercial LiFePO₄ cathodes demonstrate high cyclability, maintaining 80% capacity retention over 500 cycles at 4 C. This work highlights the vital role of multifunctional coating in promoting the electrochemical performance of Si-based anodes for high-performance LIBs.