Heterostructure Engineering of Core-Shelled Sb@Sb 2 O 3 Encapsulated in 3D N-Doped Carbon Hollow-Spheres for Superior Sodium/Potassium Storage

In this work, the core-shelled Sb@Sb O 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@Sb O 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@Sb O heterostructure, which validated that the coupling between the high-conductivity of Sb and the stability of Sb O 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 ≈573 mA h g for sodium-ion battery (SIB) anode and ≈474 mA h g for potassium-ion battery (PIB) anode at 100 mA g , and superior rate performance (302 mA h g at 30 A g for SIB anode, while 239 mA h g at 5 A g for PIB anode).