Triple engineering boosts high-performance accordion-like vanadium oxide for practical aqueous zinc-ion batteries

Vanadium oxide is one of promising cathode materials for aqueous zinc-ion batteries (ZIBs), but the low electrical conductivity and slow ion diffusion kinetics of vanadium oxide lead to low practical capacity and poor cycling life, which limits further commercialization development. Herein, this study proposes a triple engineering strategy of N-doping, oxygen vacancies and crystal water to achieve the high-performance of V₂O₅ by a simple stirring method. N doping can improve the electrical conductivity of the materials, oxygen vacancies can modulate the electronic structure, and the crystal water can effectively shield the electrostatic effect. First-principles calculations confirmed that the incorporation of the triple engineering strategies can effectively reduce of the energy band gap and Zn²⁺ diffusion barrier of V₂O₅, and promote the intercalation dynamics of Zn²⁺. As a result, the prepared N-doped V₂O_5-x·nH₂O achieves an outstanding specific capacity of 607.74 mAh/g at 0.1 A/g, and cycling stability. Moreover, based on the above advantages, the practical 21700-type cylindrical battery assembled with this N-doped V₂O_5-x·nH₂O cathode and Zn foil anode, presenting a maximum capacity of 393.5 mAh at 0.4 A. This high performance of vanadium oxide cathode shows a good practical prospect in aqueous cylindrical ZIBs.