Sulfur-doped carbon interface modification for high-performance silicon anodes in lithium-ion batteries†

Abstract

Silicon anodes are extensively investigated as a leading candidate for next-generation lithium-ion battery anode materials. However, challenges, including severe side reactions and substantial volume expansion, which result in rapid capacity fading, remain significant obstacles to their further application, particularly under high-rate charge/discharge conditions. In this study we designed a multifunctional sulfur-doped carbon layer (SDCL) on the silicon of particle surfaces. DFT demonstrates that sulfur doping modifies the carbon layer's electron cloud distribution to enhance electronic conductivity while reducing lithium-ion diffusion energy barriers, thereby facilitating fast-charging of the silicon anode. Moreover, the incorporation of sulfur promotes the formation of a more stable solid electrolyte interphase, which stabilizes the silicon structure and improves cycling durability. The resulting silicon-based anode material exhibits superior rate capability and retains 95% of its capacity after 200 cycles, with a specific capacity of 920 mA h g⁻¹. Finally, the full cell displays a capacity retention of 72.9% after 100 cycles at 2 C. In summary, this work highlights the impact of interface modification by sulfur doping on the silicon anode materials, hence offering a new approach for the development of fast-charging and durable silicon anodes in lithium-ion batteries.