Zinc storage mechanism and gas production analysis of chestnut-like V6O13·xH2O in aqueous zinc-ion batteries under different voltage windows

Abstract

Aqueous zinc-ion batteries (ZIBs) have attracted considerable attention due to their abundant resources and high safety, making them strong candidates for the next generation of energy storage devices. Vanadium-based cathode materials exhibit higher specific capacity and high rate performance, but their stability needs to be improved and issues such as low stability and gas evolution need to be addressed. In response, a solvothermal method was used in this study to synthesize chestnut-like V₆O₁₃ hydrated oxide materials. V₆O₁₃·xH₂O was investigated for its specific capacitance, rate performance, stability and gas evolution behavior at different voltage ranges. The results show that V₆O₁₃·xH₂O exhibits excellent specific capacitance and rate performance operating from 0.2 to 1.4 V, while exhibiting no gas evolution during cycling. In contrast, when the voltage is increased above 1.5 V, V₆O₁₃·xH₂O shows a distinct activation plateau during the first charge, accompanied by the intercalation of H₃O⁺ in addition to Zn ions and a phase transition of the material, leading to a noticeable gas evolution at the electrode, which is detrimental to practical use. Furthermore, in the voltage range of 0.2–1.4 V, V₆O₁₃·xH₂O exhibits superior cycling stability over extended cycles.