Enhancing the Anode Performance of Antimony through Nitrogen-Doped Carbon and Carbon Nanotubes

Antimony is a promising high-capacity anode material in sodium-ion batteries, but it generally shows poor cycling stability because of its large volume changes during sodium ion insertion and extraction processes. To alleviate or even overcome this problem, we develop a hybrid carbon encapsulation strategy to improve the anode performance of antimony through the combination of antimony/nitrogen-doped carbon (Sb/N-carbon) hybrid nanostructures and the carbon nanotube (CNT) network. When evaluated as an anode material for sodium-ion batteries, the as-synthesized Sb/N-carbon + CNT composite exhibits superior cycling stability and rate performance in comparison with Sb/N-carbon or Sb/CNT composite. A high charge capacity of 543 mA h g^-1 with initial charge capacity retention of 87.7% is achieved after 200 cycles at a current density of 0.1 A g^-1. Even under 10 A g^-1, a reversible capacity of 258 mA h g^-1 can be retained. The excellent sodium storage properties can be attributed to the formation of Sb-N bonding between the antimony nanoparticle and the nitrogen-doped carbon shell in addition to the electronically conductive and flexible CNT network. The hybrid carbon encapsulation strategy is simple yet very effective, and it also provides new avenues for designing advanced anode materials for sodium-ion batteries.