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

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 >10000 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.