VN nanoparticle-assembled hollow microspheres/N-doped carbon nanofibers: An anode material for superior potassium storage

Abstract Thanks to inexpensive and bountiful potassium resources, potassium ion batteries (PIBs) have come into the spotlight as viable alternatives for next-generation battery systems. However, poor electrochemical kinetics due to the large size of the K+ is a major challenge for PIB anodes. In this paper, an ingenious design of VN nanoparticle-assembled hollow microspheres within N-containing intertwined carbon nanofibers (VN-NPs/N-CNFs) via an electrospinning process is reported. Employed as PIB anodes, VN-NPs/N-CNFs exhibit a superb rate property and prolonged cyclability, surpassing that of other reported metal nitride-based anodes. This is ascribed to: (i) the VN NP-assembled hollow microspheres, which shorten the K+ diffusion distance, and mitigate volume expansion; and (ii) the interconnected N-CNFs, which supply numerous active sites for K+ adsorption and facilitate rapid electron/ion transport.