Rational Design of Ion-Conductive Layer on Si Anode Enables Superior-Stable Lithium-Ion Batteries

Abstract

Silicon (Si) is considered a promising commercial material for the next-generation of high-energy density lithium-ion battery (LIB) due to its high theoretical capacity. However, the severe volume changes and the poor conductivity hinder the practical application of Si anode. Herein, a novel core–shell heterostructure, Si as the core and V₃O₄@C as the shell (Si@V₃O₄@C), is proposed by a facile solvothermal reaction. Theoretical simulations have shown that the in-situ-formed V₃O₄ layer facilitates the rapid Li⁺ diffusion and lowers the energy barrier of Li transport from the carbon shell to the inner core. The 3D network structure constructed by amorphous carbon can effectively improve electronic conductivity and structural stability. Benefiting from the rationally designed structure, the optimized Si@V₃O₄@C electrode exhibits an excellent cycling stability of 1061.1 mAh g⁻¹ at 0.5 A g⁻¹ over 700 cycles (capacity retention of 70.0%) with an average Coulombic efficiency of 99.3%. In addition, the Si@V₃O₄@C||LiFePO₄ full cell shows a superior capacity retention of 78.7% after 130 cycles at 0.5 C. This study opens a novel way for designing high-performance silicon anode for advanced LIBs.