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

Abstract

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 V2O5-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 V2O5-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.