BiSb@Bi2O3/SbOx encapsulated in porous carbon as anode materials for sodium/potassium-ion batteries with a high pseudocapacitive contribution.

Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) are emerging next-generation energy storage technology, and exploiting applicative electrode materials to accommodate the large-sized Na+ and K+ are urgently needed. Herein, an innovative composite of BiSb@Bi2O3/SbOx nanoparticles encapsulated in porous carbon (BiSb@Bi2O3/SbOx@C) is fabricated through a template-assisted in-situ pyrogenic decomposition and evaluated as anodes for SIBs and PIBs. The BiSb@Bi2O3/SbOx@C delivers high specific capacity, superior rate capability (205 mA h g-1 and 111 mA h g-1 at 2 Ah g-1) and good cycling stability (248 mA h g-1 and 214 mA h g-1 after 500 cycles at 1 A g-1) in SIBs and PIBs. The excellent performance owes to the synergistic effect of Bi and Sb, the multilayer nanostructure design as well as the interconnected porous carbon network, which effectively promotes electron transport and ion diffusion, restricts volume change and enhances the electrode structure stability simultaneously. Furthermore, the capacitive behavior contributes much to the storage of sodium and potassium ions, which guarantees a superior rate capability. This research opens up new opportunities for exploring high-performance anodes for SIBs and PIBs.