Hierarchical Bismuth-Carbon Microfoam Hybrid Structure Achieves Superior Sodium-Ion Storage

Bismuth (Bi) has been deemed as an attractive anode candidate for sodium-ion batteries (SIBs) due to its high theoretical volumetric capacity (3800 mAh cm(-3)), stable operating potential, and nontoxicity. However, a large volume change during the alloying/dealloying reaction leads to inferior cycling performance. Herein, we constructed a hierarchical bismuth-carbon microfoam-like hybrid structure composed of interconnecting Bi nanoparticles coated with a carbon shell on a carbon matrix nanocomposite (denoted as Bi@NC-MF) by a scalable and costeffective approach, which exhibits excellent sodium-ion storage performance in terms of high specific capacity and excellent cycling stability and rate capability. Specifically, it can achieve an extraordinary capacity retention rate of 98% after 2000 cycles at a high rate of 10 A g(-1). Impressively, remarkable rate capability with a capacity retention of 91% can be achieved when the current density increases from 0.5 to 40 A g(-1). More importantly, a full cell by pairing the Bi@NC-MF anode with a commercial Na3V2(PO4)(3)/C cathode exhibits promising performance with a decent energy density of 180.6 Wh kg(-1) at a power density of 59 W kg(-1). This work not only provides a scalable strategy for advanced hybrid nanostructures but also stimulates the advancement of Bi-based anodes for future practical applications.