Heterostructure Engineering of Core-Shelled Sb@Sb2O3 Encapsulated in 3D N-Doped Carbon Hollow-Spheres for Superior Sodium/Potassium Storage

In this work, the core-shelled Sb@Sb2O3 heterostructure encapsulated in 3D N-doped carbon hollow-spheres is fabricated by spray-drying combined with heat treatment. The novel core-shelled heterostructures of Sb@Sb2O3 possess a mass of heterointerfaces, which formed spontaneously at the core-shell contact via annealing oxidation and can promote the rapid Na+/K+ transfer. The density functional theory calculations revealed the mechanism and significance of Na/K-storage for the core-shelled Sb@Sb2O3 heterostructure, which validated that the coupling between the high-conductivity of Sb and the stability of Sb2O3 can relieve the shortcomings of the individual building blocks, thereby enhancing the Na/K-storage capacity. Furthermore, the core-shell structure embedded in the 3D carbon framework with robust structure can further increase the electrode mechanical strength and thus buffer the severe volume changes upon cycling. As a result, such composite architecture exhibited a high specific capacity of approximate to 573 mA h g(-1) for sodium-ion battery (SIB) anode and approximate to 474 mA h g(-1) for potassium-ion battery (PIB) anode at 100 mA g(-1), and superior rate performance (302 mA h g(-1) at 30 A g(-1) for SIB anode, while 239 mA h g(-1) at 5 A g(-1) for PIB anode).

Automated summary

In this study, a core-shelled Sb@Sb2O3 heterostructure encapsulated in 3D N-doped carbon hollow-spheres was successfully fabricated, which not only promotes Na+/K+ transfer, but also increases storage capacity and alleviates volume changes during cycling. Experimental results show that this composite structure exhibits excellent performance in both sodium-ion battery and potassium-ion battery applications.