Self-Supporting VO 2 @MXene Electrode with the Boosted Zn 2+ (De)intercalation Kinetics and Cycling Stability for Aqueous Zincion Battery

Abstract

Vanadium dioxide (VO2) with the high theoretical capacity is one of the promising cathodes of aqueous zinc-ion batteries (AZIBs) for safe and sustainable energy storage. But the poor electrical conductivity and structural degradation have limited the rate performance and long-term stability. Herein, we present a self-supporting hierarchical VO2@MXene electrode without current collector and additive for AZIBs, where VO2 nanostructures are intimately anchored within a highly conductive MXene layers. The highly conductive and highly flexible Mxene forms a high-conductivity network, facilitating the rapid transmission of electrons/ions, while providing a buffer for the structural changes of VO2, effectively promoting the structural robustness during the cycling process. Systematic investigation reveals a strong synergistic effect between VO2 and MXene. With an optimal VO2-to-MXene mass ratio of 1:1, the cathode delivers a high discharge capacity of 587.7 mA h g -1 at 1 A g -1 and maintains a remarkable capacity of 361.1 mA h g -1 after 1000 cycles at 5 A g -1 . This work presents a transformative strategy for achieving high-energy-density AZIB in flexible electronics and large-scale grid storage through the design of a self-supporting electrode architecture that eliminates the use of current collectors, binders, and conductive additives.