Bismuth nanorods confined in hollow carbon structures for high performance sodium- and potassium-ion batteries

Bismuth has drawn widespread attention as a prospective alloying-type anode for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) due to its large volumetric capacity. However, such material encounters drastic particle pulverization and overgrowth of solid-electrolyte interphase (SEI) upon repeated (de)alloying, thus causing poor rate and cycling degradation. Herein, we report a unique structure design with bismuth nanorods confined in hollow N, S-codoped carbon nanotubes ([email protected]) fabricated by a solvothermal method and in-situ thermal reduction. Ex-situ SEM observations confirm that such a design can significantly suppress the size fining of Bi nanorods, thus inhibiting the particle pulverization and repeated SEI growth upon charging/discharging. The as achieved [email protected] demonstrates outstanding rate capability for SIBs (96.5% capacity retention at 30 A g−1 vs. 1 A g−1), and a record high rate performance for PIBs (399.5 mAh g−1 @ 20 A g−1). Notably, the as constructed full cell (Na3V2(PO4)3@C|[email protected]) demonstrates impressive performance with a high energy density of 219.8 W h kg−1 and a high-power density of 6443.3 W kg−1 (based on the total mass of active materials on both electrodes), outperforming the state-of-the-art literature.