Design and synthesis of SiO@SiO₂ core–shell anodes for enhanced performance in lithium-ion batteries

Abstract

The progress of energy storage technology crucially depends on the availability of high-performance lithium-ion batteries (LIBs). As a silicon-based composite material, silicon oxide (SiO) exhibits significant theoretical specific capacity and mitigates the volume expansion of pure silicon. However, poor electronic conductivity remains a significant issue, limiting the performance of LIBs. In this study, SiO@SiO₂ composites were synthesized by applying a silane coupling agent as the silicon source to coat silicon oxides onto the surface of micrometer-sized SiO particles using an in situ coating technique within a liquid-phase system. This approach aims to address the problems of volume expansion and stability, thereby enhancing the performance of LIBs. The silicon oxide core provides high capacity, whereas the silica shell serves as a protective layer. The SiO₂ shell, with its greater rigidity compared to a carbon shell, better inhibits volume expansion, thereby extending the battery’s service life. The results showed that when the mass of the silane coupling agent (SCA) was 15% of the mass of the SiO particles, the initial specific capacity of SiO@SiO₂-15 composites reached 2160.62 mAh·g⁻¹, with the highest first coulombic efficiency (70.06%). Additionally, the composites exhibited the highest reversible capacity (1345.54 mAh·g⁻¹) and a capacity retention of 62.28% after 100 cycles.