Facile strategy for synthesis of mesoporous ZnSe nanobelts coated with nitrogen-doped carbon as high-performance anodes for potassium-ion batteries

K-ion batteries (KIBs) are attracting considerable attention due to low price of K resources and their low redox potential. However, poor electrochemical performance of anode materials caused by the large ion diameter of K+ must be imperatively addressed. In this study, we designed mesoporous ZnSe nanobelts coated with N-doped carbon (MP-ZnSe@NC) using a facile method for high-performance KIBs. A belt-like ZnSe[diethylenetriamine]0.5 (ZnSe[DETA]0.5) precursor, obtained from a facile autoclave reaction, was coated with polydopamine in an alkaline medium, followed by thermal treatment to fabricate the MP-ZnSe@NC nanobelt. During the thermal process, inner mesopores are generated owing to the local volume change by the carbonization of DETA molecules, which can facilitate K+ diffusion rate and alleviate the mechanical strain stress. In addition, the lateral confinement effect of the nanobelt and the presence of a N-doped carbon shell can provide a highly conductive pathway for electrons and structural robustness for the electrode. Owing to these advantages, the MP-ZnSe@NC electrode exhibited a stable reversible capacity (247 mA h g−1 at 0.5 A g−1 after 500 cycles) and remarkable rate capability (∼100 mA h g−1 at 2.0 A g−1). Further, the K-ion full cell demonstrated the potential of the MP-ZnSe@NC nanobelt anode for practical applications.