Self‐Transformation Strategy Toward Vanadium Dioxide Cathode For Advanced Aqueous Zinc Batteries

Abstract

AbstractIn the lithium‐dominated era, rechargeable Zn batteries are emerging as a competitive alternative. However, the sluggish kinetics of ion diffusion and structural destruction of cathode materials have thus far hampered the realization of future large‐scale energy storage. Herein, an in situ self‐transformation approach is reported to electrochemically boost the activity of a high‐temperature, argon‐treated VO2 (AVO) microsphere for effective Zn ion storage. The presynthesized AVO with hierarchical structure and high crystallinity allows efficient electrochemical oxidation and water insertion to induce self‐phase transformation into V2O5·nH2O within the first charging process, which leads to rich active sites and fast electrochemical kinetics. Using AVO cathode, an outstanding discharge capacity of 446 mAh g−1 at 0.1 A g−1, high rate capability of 323 mAh g−1 at 10 A g−1 and excellent cycling stability for 4000 cycles at 20 A g−1 with high capacity retention are demonstrated. Importantly, such zinc‐ion batteries with phase self‐transition can also perform well at high‐loading, sub‐zero temperature, or pouch cell conditions for practical application. This work not only paves a new route to design in situ self‐transformation in energy storage devices, but also broadens the horizons of aqueous zinc‐supplied cathodes