Synthesizing Si/SiOC composites through different sol-gel reaction routes for lithium-ion battery anode materials

Abstract

Silicon oxycarbide (SiOC) exhibits good retention and a reasonable specific capacity and is an alternative to silicon used as an anode material for high-performance lithium-ion batteries. However, SiOC generally shows a low Initial Coulombic Efficiency (ICE), wasting the lithium from the cathode. This work explores different sol-gel routes to synthesize SiOC from silanes and compares their performance. We found that the crushed bulk acid-catalyzed SiOC is simple and cost-effective but with excellent performance. Adding dimethyldimethoxysilane (DMDMS) by decreasing the oxygen content further enhances the battery performance. Building upon the excellent performance of SiOC, we further embed nano-silicon into SiOC. The Si/SiOC composites achieved a significantly higher specific capacity of 2185 mAhg−1 and an impressive ICE of 77 % with acceptable battery retention.

Keywords

• Silane
• Spherical SiOC
• Bulk SiOC
• Si/SiOC composite
• Lithium-ion battery
• Anode material