Si trova su / Altri legami
© Anhydrous α–V2O5 was the first class of cathodes studied for rechargeable aqueous zinc–ion batteries (AZIBs), mainly due to its layered structure and high theoretical capacity. However, the poor cycle life of Zn/α–V2O5 prevents it from being used as a practical cathode. A critical need for the advancement of high–capacity aqueous Zn/α–V2O5 batteries is a better understanding of the degradation mechanisms in an α–V2O5 cathode. Through a combined experimental and theoretical approach, we here report that the stability of an α–V2O5 cathode in aqueous Zn/α–V2O5 batteries is fundamentally controlled by its dissolution mechanisms in water and concurrent phase transition to a hydrated V2O5·1.75H2O (H–V2O5) xerogel. We show that α–V2O5 partially dissolves as [V10O26(OH)2]4– into aqueous ZnSO4 but precipitates out as Zn3(OH)2V2O7·2H2O in aqueous Zn(CF3SO3)2, while its majority is transformed into H–V2O5. We provide evidence that H–V2O5 is the active material for the storage of Zn2+/H+ due to its favorable gallery spacing for intercalation chemistry. Overall, presented experimental evidence and gained fundamental insights by this study contribute to the advancement of high–capacity aqueous Zn/α–V2O5 batteries.
