Evaporation-induced formation of hollow bismuth@N-doped carbon nanorods for enhanced electrochemical potassium storage

Metal bismuth (Bi) is recognized as an attractive anode material for potassium ion batteries in virtue of its good conductivity and relatively low working potential. However, the large volume expansion during the discharge/charge process leads to poor cycling stability. Herein, Bi nanorods encapsulated in nitrogen-doped carbon nanotubes (hollow Bi@C nanorods) are fabricated via in-situ reduction and carbonization of polydopamine-coated Bi2S3 nanorods and the following partial evaporation of Bi. Benefiting from the robust hollow structure and outer conductive carbon shells, the hollow Bi@C nanorods electrodes achieve a high reversible capacity of about 353 mAh g(-1) at 0.05 A g(-1) and good cycling stability with a capacity retention of 80.3% over 300 cycles at 0.5 A g(-1). Moreover, by pairing the hollow Bi@C anode and potassium Prussian blue cathode, the K-ion full cell exhibits a high capacity retention of 88.6% after 100 cycles.