Highly sulfur-doped porous carbon enhances sodium-ion storage with superior rate capability and long cycling stability

The pressing needs for sustainable energy storage become driving force for wide range of battery technologies, including sodium-ion batteries (SIBs), as a probable substitute for commonly used lithium-ion batteries (LIBs). However, it remains a critical challenge to enhance the electrochemical performance of SIBs. This study addresses these challenges by exploring the potential of sulfur-doped biomass carbon as a promising anode material for SIBs. Using a molten salt method with a Na₂SO₃@LiCl/KCl system, sulfur was introduced into biomass carbon to significantly improve its electrochemical properties. The sulfur doping enhanced the material’s conductivity, created additional active sites, and facilitated sodium-sulfur (Na–S) reactions, which contributed to superior electrochemical performance. The high sulfur doped hard carbon (HS-HC) electrode exhibited exceptional rate capability, retaining high specific capacity at elevated current densities, and demonstrated remarkable cycling stability with a capacity retention of 95% after 3100 cycles. These findings not only highlight the potential of sulfur-doped biomass carbon for improving the performance of SIBs but also offer a sustainable and cost-effective solution for next-generation energy storage systems.