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 (∼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 three-dimensional (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.