Sodium-Ion Storage of Antimony Sulfide Enabled by Dual-Carbon Confinement.

Antimony trisulfide (Sb2S3) as an anode material for sodium-ion batteries shows a theoretical specific capacity of 954 mAh g-1, but its poor intrinsic electrical conductivity, severe volume expansion, formation/shuttling of polysulfide during sodiation/desodiation processes, and low initial Coulombic efficiency severely hinder its practical application. In this work, reduced graphene oxide (rGO) sheets are coated first on antimony trisulfide nanorods that are further embedded in a pitch pyrolytic carbon matrix to yield ternary composites (Sb2S3@rGO@C). The rGO sheets can increase ion transport pathways and ameliorate the reaction kinetics of Sb2S3. The pitch-derived pyrolytic carbon matrix not only reduces the specific surface area of the composite and enhances the initial Coulombic efficiency, but also suppresses the volume variation of Sb2S3. The C-S chemical bonds formed within the composites can inhibit polysulfide shuttling and further improve the sodiation/desodiation cycling stability. The as-prepared Sb2S3@rGO@C anode exhibits a high initial Coulombic efficiency of 82.2%, excellent cycling stability (delivering a specific capacity of 375.1 mAh g-1 even after 800 cycles at 1.0 C), and outstanding rate capability (maintaining a specific capacity of 495.5 mAh g-1 at a high current density of 2.0 C).