Sulfur-doped carbon spheres with hierarchical micro/mesopores as anode materials for sodium-ion batteries

In this work, sulfur-doped carbon spheres with hierarchical micro/mesopores (denoted as S-MCSs) were fabricated via a sol-gel method combined with surfactant-directing assembly strategy and subsequent sulfuration process. When used as anode materials of sodium-ion batteries (SIBs), S-MCSs show excellent electrochemical performance with a high maximum reversible capacity of 443.4 mA h g⁻¹ after 50 cycles at 50 mA g⁻¹, and even at a high current density of 1 A g⁻¹, a reversible capacity of 238.2 mA h g⁻¹ is obtained after 600 cycles, mainly due to their hierarchical micro/mesoporous structure with high specific surface area, large pore volume and high sulfur content. The excellent cycling performance and high capacity enable the S-MCSs to be a promising candidate for SIBs.