Seed-mediated formation of multiphase zero-valent Sb nanoparticles as alloying-type anodes for sodium-ion batteries with high capacity and ultra-long durability

Abstract

The development of stable electrode materials with high specific capacities is of paramount importance for sodium-ion batteries (SIBs) to make them competitive with lithium-ion batteries (LIBs). This study reports the use of a Co-seed-mediated method for the synthesis of CNT-supported multiphase zero-valent Sb nanoparticles in the forms of Sb, CoSb, and CoSb₂ with nitrogen-doped carbon coating (NC@CoSb/CNTs-400). The obtained NC@CoSb/CNTs-400 shows high capacities and excellent durability for sodium storage. It can exhibit high stable reversible capacities of 352.4 and 330.4 mA h g⁻¹ at 0.1 and 1.0 A g⁻¹, respectively, and deliver outstanding rate-capacities of 263.8 and 243.9 mA h g⁻¹ at 5.0 and 10.0 A g⁻¹, respectively. No obvious capacity drops are observed when it is sodiated/desodiated at 5.0 and 10.0 A g⁻¹ for >10 000 cycles, respectively. Its superior performance arises from the unique structure. Specifically, the multiphase Sb NPs in the forms of Sb, CoSb, and CoSb₂ increase the accessibility of Sb to sodium storage, improving the specific capacities of NC@CoSb/CNTs-400. The NC coating and CNT support increase the stability of NC@CoSb/CNTs-400, endowing it with excellent durability.