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

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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 cost-effective 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 Na 3 V 2 (PO 4 ) 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.