A self-supporting VO2@MXene electrode with boosted Zn2+ (de)intercalation kinetics and cycling stability for aqueous zinc-ion batteries.

Abstract

Vanadium dioxide (VO2) with its high theoretical capacity is one of the promising cathodes for aqueous zinc-ion batteries (AZIBs) for safe and sustainable energy storage. However, its poor electrical conductivity and structural degradation have limited its rate performance and long-term stability. Herein, we present a self-supporting hierarchical VO2@MXene electrode without a current collector and additives for AZIBs, in which VO2 nanostructures are intimately anchored within 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, thereby effectively promoting its structural robustness during the cycling process. A systematic investigation reveals a strong synergistic effect between VO2 and MXene. With an optimal VO2-to-MXene mass ratio of 7 : 3, the cathode delivers a high discharge capacity of 587.7 mAh g-1 at 1 A g-1 and maintains a remarkable capacity of 336 mAh g-1 after 1000 cycles at 5 A g-1. This work presents a transformative strategy for achieving high-energy-density AZIBs for flexible electronics and large-scale grid storage through the design of a self-supporting electrode architecture that eliminates the need for current collectors, binders, and conductive additives.