Internal Reinforcement and External Protection: Dual Aluminum-Based Modifications Endow Silica Anodes with Excellent Cycling Stability

Silica (SiO2) is considered a potential negative electrode material for next-generation lithium-ion batteries due to its high theoretical capacity. However, SiO2 as an anode material is limited by the side reactions at the electrical conductivity and the silicon/electrolyte interface. Based on a dual-design strategy encompassing bulk structural regulation and interfacial chemical construction, this article proposes a synergistic modification approach combining aluminum doping and Al2O3 coating. The bulk doping Al induces freely migrating holes, thereby enhancing the material’s electronic conductivity. And the Al2O3 coating acts as a physical barrier to prevent the invasion of hydrogen fluoride by the electrolyte decomposition, thereby improving cycling performance. After cycling at a current density of 500 mA·g–1, the excellent discharge capacity of 500 mAh·g–1 can be maintained at 400 cycles, and after cycling at a current density of 2000 mA·g–1, the excellent rate performance of 200 mAh·g–1 can be maintained at 1000 cycles. The full battery can maintain a high energy density of 352.8 Wh·kg–1 during the 1C charging and discharging cycle. This study elucidates the intrinsic mechanisms behind the performance enhancement from the perspectives of defect chemistry and interfacial reaction kinetics, providing theoretical insights and practical pathways for the design of high-stability silicon-based anode materials.