g-C3N4 confined Sb2Se3 as high-performance anode towards rapid and stable Na-ion storage

Sb2Se3 is considered a promising anode material for sodium-ion batteries (SIBs) due to its abundant reserves, low cost, and high theoretical capacity. Nevertheless, significant volume changes and slow electron transfer kinetics significantly limit its rate capability and cycle stability. In this work, we constructed g-C3N4-coated Sb2Se3 nanorods (Sb2Se3@g-C3N4) through the hydrothermal method and subsequent thermal treatment to enhance kinetics and achieve high cycle stability. The coating enhances the structure stability, insertion/extraction reversibility of Na+, and electrochemical reaction activity. Benefiting from the unique structure and composition, Sb2Se3@g-C3N4 (8 wt%) nanorod exhibits excellent rate properties with high desodiation capacities of 376.7, 345.5, 336.1, 322.7, 301.4, and 275.0 mAh g−1 at 0.1, 0.5, 1, 2, 5, and 10 A g−1, respectively. Even at 5 A g−1, Sb2Se3@g-C3N4 (8 wt%) exhibits high cycle stability with a capacity retention of approximately 86.7% after 600 cycles. Ex-situ XRD and XPS results confirm that the introduction of g-C3N4 on the surface of Sb2Se3 inhibits the volumetric expansion and electrode pulverization of Sb2Se3, thereby improving the structural stability of the composite material, resulting in an excellent electrochemical capability of Sb2Se3@g-C3N4 nanorods. Sb2Se3@g-C3N4 nanorods show massive potential as an anode material for the next-generation high-performance SIBs.