Simultaneous modulation of oxygen and carbon compositions in SiOC ceramics for high‐capacity and durable anode materials

Abstract Phenyl‐rich silicone (Si) oil is successfully cured through the protodesilylation reaction using sulfuric acid, and its subsequent inert pyrolysis significantly improved the yield of the SiOC ceramics. By varying the amount of sulfuric acid during the reaction, the carbon and oxygen compositions in the resulting SiOC ceramics were effectively modulated. Increasing the sulfuric acid content led to greater oxygen incorporation within the ceramic phase, providing additional lithium storage sites. Furthermore, the protodesilylation reaction reduced the carbon content while simultaneously improving carbon crystallinity. SiOC 1.5 with optimal oxygen and carbon content, prepared at an H 2 SO 4 /Si oil molar ratio of 1.5, demonstrated the highest electrochemical performance. This sample achieved an initial coulombic efficiency (ICE) of 68% and exhibited a remarkable lithium storage capacity of 935 mAh/g at a current density of 0.1 A/g. This study introduces a novel method for controlling oxygen and carbon content in SiOC ceramics through the oxidation of Si oil via acid treatment. We believe that these findings provide valuable insights and open a new pathway for the design and synthesis of SiOC precursors with tailored electrochemical properties.