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

Abstract

In this work, the core-shelled Sb@Sb₂ O₃ 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@Sb₂ O₃ 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@Sb₂ O₃ heterostructure, which validated that the coupling between the high-conductivity of Sb and the stability of Sb₂ O₃ 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^-1 for sodium-ion battery (SIB) anode and ≈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).