<i>In Situ</i> Electrochemically Activated Vanadium Oxide Cathode for Advanced Aqueous Zn-Ion Batteries.

Wang, Xiao; Zhang, Zhengchunyu; Huang, Man; Feng, Jinkui; Xiong, Shenglin; Xi, Baojuan · Nano Lett · 2022

basic_science · Level V

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Abstract

The search for large-capacity and high-energy-density cathode materials for aqueous Zn-ion batteries is still challenging. Here, an <i>in situ</i> electrochemical activation strategy to boost the electrochemical activity of a carbon-confined vanadium trioxide (V<sub>2</sub>O<sub>3</sub>@C) microsphere cathode is demonstrated. Tunnel-structured V<sub>2</sub>O<sub>3</sub> undergoes a complete phase transition to a layered, amorphous, and oxygen-deficient Zn<sub>0.4</sub>V<sub>2</sub>O<sub>5-<i>m</i></sub>·<i>n</i>H<sub>2</sub>O on the first charge, thus allowing subsequent (de)intercalation of zinc cations on the basis of the latter structure, which can be regulated by the amount of H<sub>2</sub>O in the electrolyte. The electrode thus delivers excellent stability with a significantly high capacity of 602 mAh g<sup>-1</sup> over 150 cycles upon being subjected to a low-current-rate cycling, as well as a high-energy density of 439.6 Wh kg<sup>-1</sup> and extended life up to 10000 cycles with a 90.3% capacity retention. This strategy will be exceptionally desirable to achieve ultrafast Zn-ion storage with high capacity and energy density.