Electrochemical performance and reaction mechanism investigation of V2O5positive electrode material for aqueous rechargeable zinc batteries

Abstract

The electrochemical performance and reaction mechanism of orthorhombic V2O5in 1 M ZnSO4aqueous electrolyte are investigated. V2O5nanowires exhibit an initial discharge and charge capacity of 277 and 432 mA h g−1, respectively, at a current density of 50 mA g−1. The material undergoes quick capacity fading during cycling under both low (50 mA g−1) and high (200 mA g−1) currents. V2O5can deliver a higher discharge capacity at 200 mA g−1than that at 50 mA g−1after 10 cycles, which could be attributed to a different type of activation process under both current densities and distinct degrees of side reactions (parasitic reactions). Cyclic voltammetry shows several successive redox peaks during Zn ion insertion and deinsertion.In operandosynchrotron diffraction reveals that V2O5undergoes a solid solution and two-phase reaction during the 1st cycle, accompanied by the formation/decomposition of byproducts Zn3(OH)2V2O7·2(H2O) and ZnSO4Zn3(OH)6·5H2O. In the 2nd insertion process, V2O5goes through the same two-phase reaction as that in the 1st cycle, with the formation of the byproduct ZnSO4Zn3(OH)6·5H2O. The reduction/oxidation of vanadium is confirmed byin operandoX-ray absorption spectroscopy. Furthermore, Raman, TEM, and X-ray photoelectron spectroscopy (XPS) confirm the byproduct formation and the reversible Zn ion insertion/deinsertion in the V2O5