Uniform Bi3Se4 @N-doped carbon spheres as anode for superior lithium and potassium storage performance

Bi3Se4 is a promising anode material for energy storage owing to its merits of layer structure and high specific capacity, however, it usually faces rapid capacity decay and poor rate performances due to the large volume expansion during ion insertion and extraction processes. Herein, Bi3Se4 @N-doped carbon spheres (Bi3Se4 @NC) were fabricated for the first time as anode material for both lithium ion batteries (LIBs) and potassium ion batteries (PIBs). The obtained Bi3Se4 @NC exhibited notable good rate capability (614.4 mAh g−1 at 0.1 A g−1 and 144.5 mAh g−1 even at 20 A g−1) and excellent cycle stability as anode for LIBs. It also displayed preeminent specific capacity of 359.3 mAh g−1 (at 50 mA g−1) and excellent rate capability (achieve capacity as high as 222.4 mAh g−1 at 300 mAh g−1) when used as anode for PIBs. The contribution of the pseudocapacitance capacity and the low resistance of the electrode material contribute to the origin of excellent rate capability. In addition, the potassium ion storage mechanism of Bi3Se4 @NC has been further examined by ex-situ XRD patterns and HRTEM analyses. The above results reveal that the Bi3Se4 @NC composite is a competitive anode material for LIBs and PIBs.