Promoting Zn2+ storage capability of a vanadium-based cathode via structural reconstruction for aqueous Zn-ion batteries

Abstract

Increasing expectation and attention are placed on vanadium oxides because of the high theoretical capacity and resource abundance for aqueous Zn-ion batteries. Nevertheless, further development of vanadium oxides is hampered by the limited capacity utilization and inferior cyclic durability. In this study, a promising VO₂·0.81H₂O (VOHO) nanorod cathode with excellent performance towards Zn²⁺ storage was developed via the structural reconstruction of commercial V₂O₅ (VO) nanoparticles by a simple hydrothermal treatment. In comparison with VO counterpart, these VOHO nanorods possess more surface electrochemically active sites and superior electric conductivity as well as much better electrolyte wettability. Correspondingly, the as-assembled Zn-ion battery with a VOHO cathode (denoted as VOHO//Zn battery) delivered an admirable specific capacity of 372.2 mA h g⁻¹ at a current density of 0.1 A g⁻¹ with markedly improved rate performance, substantially larger than that of the VO//Zn (238.6 mA h g⁻¹). Also, this VOHO//Zn device afforded an exceptional energy density of 226.7 W h kg⁻¹, accompanied by superior cyclic durability without any capacity fading after 1000 cycles. This structural reconstruction strategy to boost the Zn²⁺ storage capability is of great significance for designing other energy-storage materials.