Electrospun V₂O₃@Carbon Nanofibers as a Flexible and Binder-Free Cathode for Highly Stable Aqueous Zn-Ion Full Batteries

Abstract

Vanadium sesquioxide (V2O3) is widely considered as a promising cathode candidate for fabricating aqueous zinc-ion batteries (AZIBs). However, some drawbacks, such as large volume variation, structural degradation, and sluggish charge transport kinetics during repeated cycling, hinder its wide application for high-performance AZIBs. Herein, we report a V2O3/carbon composite with V2O3 nanoparticles (NPs) embedded in carbon nanofibers (denoted as V2O3@C NFs) as a flexible and binder-free cathode material for AZIBs. The V2O3@C NFs was prepared via an electrospinning method, followed by stabilization and carbonization treatments, resulting in nano-sized V2O3 crystals with a tunnel-like 3D phase structure uniformly distributed in N-doped carbon NFs with a partial graphite structure and some structural defects. As a result, the V2O3@C NFs used as a flexible and binder-free cathode can deliver high initial capacity (220 mA h g–1 at 50 mA g–1), excellent cycling stability (120/65 mA h g–1 at 200/2000 mA g–1 after 1000 cycles), and enhanced rate capability (100 mA h g–1 at 2000 mA g–1). To gain insights into efficient Zn storage, the diffusion and storage mechanism of Zn2+ ions in the cathode material was initially elucidated via theoretical simulations based on first-principles calculations. Furthermore, a full battery was facilely assembled on the basis of V2O3@C NFs, and it showed a desirable practical application potential. This work thus offers some guidance for the design and synthesis of flexible and binder-free vanadium-based cathode materials for AZIBs.