Porous Sb Nanocubes Embedded in Three-Dimensional Interconnected Nitrogen-Doped Carbon Frameworks for Enhanced Sodium Storage

Antimony (Sb) has been considered an attractive anode material for sodium-ion batteries (SIBs) because of its high theoretical capacity (660 mAh g(-1)), abundant resources, and relatively safe working potential (similar to 0.8 V). However, such an anode still suffers from huge volume change and repeated formation/destruction of a solid electrolyte interface (SEI) at the interface upon sodiation/de-sodiation, thus leading to poor electrochemical performance. To address these issues, we design and construct a unique hybrid nanostructure built from hollow/porous Sb nanocubes embedded in interconnected nitrogen-doped carbon frameworks. Such a hybrid combines the merits of internal void engineering for the Sb anode and threedimensional (3D) continuous conductive protection layer where the former can efficiently accommodate the structural strain upon sodiation and de-sodiation processes, while the latter not only prevents the direct contact of an electrolyte and active component but also provides a high-efficiency electron/ion transport system, consequently leading to higher structure/interface stability and better sodium storage capability. When evaluated as an anode for SIBs, such a hybrid delivers reversible capacities of 588.8 mAh g(-1) at 0.05 A g(-1) and 359.4 mAh g(-1) at 2 A g(-1), as well as retains a specific capacity of 347.8 mAh g(-1) after 200 cycles at 1 A g(-1). Our work provides a simple and effective strategy to construct a unique 3D interconnected hybrid architecture with a simultaneously improved structure and interface stability for the alloying-based anode.