N-Doped carbon coated bismuth nanorods with a hollow structure as an anode for superior-performance potassium-ion batteries

Bismuth (Bi) is a promising anode material for potassium-ion batteries due to its high energy density. However, the large volume change limits its applications. Herein, N-doped carbon coated Bi nanorods with a hollow structure are fabricated and they exhibit excellent long-term cycling performance (88% capacity retention over 1000 cycles) and high-rate ability (297 mA h g(-1) at 20C, 94% capacity of that at 1C). Furthermore, the mechanism was expounded by in situ XRD, indicating a multi-phase reaction for the initial discharge process and three two-phase reactions for the subsequent charge/discharge processes.