Modification with graphite and sulfurized amorphous carbon for high-performance silicon anodes in lithium-ion batteries

Silicon-based materials are considered among the most promising anode materials for the next generation of lithium-ion batteries due to their abundant reserves, high theoretical capacity, and lower discharge potentials. However, the poor conductivity, significant volume expansion, and severe capacity fading of silicon hinder its commercial application. The synergistic use of silicon and graphite is an effective way to address these issues but faces problems such as persistent interface and structural stability challenges. This study employs sulfur-doped carbon derived from sulfonated polyacrylonitrile to encapsulate silicon, with graphite serving as the conductive medium. Through a combined wet chemical and pyrolysis process, we synthesized Si@SPANdC/Gr composite materials with superior electrochemical performance. The 3gSi@SPANdC/Gr composite anode material, containing a low silicon content (similar to 19.1 wt%), demonstrated a reversible capacity of 628.8 mAh g(-1) at a current density of 0.2 A g(-1) over 200 cycles, with an initial Coulombic efficiency of 71.28 %. Even at a higher current density of 1 A g(-1), it maintained a relatively high reversible capacity of 516.8 mAh g(-1) after 400 cycles, indicating good cycle stability. In addition, a full cell assembled with the 3gSi@SPANdC/Gr anode and commercial LiCoO4 cathode also shows an impressive cycling performance. This research provides a low-cost and novel solution for the commercial application of high-performance silicon-based lithium-ion batteries.