Double-enhanced core-shell Sb@Sb2O3 heterostructure encapsulated in porous carbon for long life sodium storage

Antimony (Sb) based materials have been regarded as highly competitive anodes sodium ion batteries (SIBs) due to their high theoretical capacity. However, it suffers from poor electrochemical performance because of the large volume expansion and the sluggish kinetics of the Na+ ions. To address the above problem, we prepare the core-shell Sb@Sb2O3 heterostructure encapsulated in a porous carbon (Sb@Sb2O3@C) as high performance anode material for SIBs. A facile NaCl template-assisted freeze-drying strategy could easily to acquire the porous carbon structure and the slow oxidation treatment process could realize the component from Sb to Sb@Sb2O3, finally Sb2O3. The perfect combination of core-shell Sb@Sb2O3 heterostructure with robust porous carbon can further accelerate the electron diffusion, promote the Na+ transfer, and enhance the structural stability of the electrode. Benefit from the advantages of structure and composition, the Sb@Sb2O3@C exhibits a long life and high rate capability for SIBs, with an initial discharge/recharge capacity of 530.2/446.7 mAh g−1 and an initial Coulombic efficiency of 84.3%. In addition, it displays a high rate capacity with 450 mA h g−1 at 1 A g−1 and excellent long-term cycling stability with 440.6 mAh g−1 after 5000 cycles even at a high current density of 5 A g−1. [Display omitted]