Dual defects boosting zinc ion storage of hierarchical vanadium oxide fibers

Abstract Vanadium oxides are considered as promising cathode materials for aqueous zinc ions batteries (AZIBs). However, the long diffusion distance, low diffusion coefficient, and strong electrostatic interactions with divalent Zn2+ in bulk vanadium oxide restrict their practical application. In this work, vanadium oxide nanofibers with physical and chemical defects were facilely fabricated by electrospinning for the application in AZIBs. The hierarchical framework exhibits structure stability during insertion/ extraction processes of zinc ions, and the extracted zinc ions are easily confined in the caverns of porous fibers to shorten the diffusion paths. Furthermore, the electrochemical reaction mechanism was verified by using in situ Raman and ex situ XPS and HRTEM, demonstrating a co-insertion mechanism of zinc ions and H+. The cathode shows a fast activation process, exhibiting a high capacity of 256 mAh g−1 at 1 A g−1, and the capacity fading of only 17% is observed after 1000 cycles at 5 A g−1. The outstanding electrochemical performances and efficient Zn2+ transportation can be attributed to the synergism of physical and chemical defects. This strategy of dual defects may provide new insights into the improvements of AZIBs performance.