Surface reconstruction of V2O5 boosting ammonium-ion storage

Developing electrode materials for aqueous ammonium-ion batteries (AAIBs) has garnered significant attention recently. Owing to its poor intrinsic conductivity, sluggish electron transfer and ion diffusion kinetics, boosting the ammonium-ion storage properties of vanadium pentoxide (V₂O₅) remains significant challenge. In this work, we develop a surface reconstruction strategy to enhance the ammonium-ion storage of V₂O₅. V₂O₅ nanowires are firstly synthesized using a hydrothermal method and then these nanowires are etched by the insufficient dilute hydrochloric acid under the pumping filtration to obtain surface reconstruction of V₂O₅ (denoted as e-V₂O₅). Both experimental and theoretical calculation results manifest that the surface reconstruction strategy can improve the conductivity, kinetic and mass/ion transport of V₂O₅, resulting in enhancing its ammonium-ion storage. The e-V₂O₅ achieves the specific capacity of 160 mAh g⁻¹ at 0.1 A g⁻¹, which is much higher than that of V₂O₅ nanowires (116 mAh g⁻¹) and even superior to the reported materials for ammonium-ion storage. The e-V₂O₅//PTCDI (3,4,9,10-perylene-bis(dicarboximide)) battery delivers E (energy density) of 112 Wh·kg⁻¹ at P (power density) of 315 W·kg⁻¹. This work not only proves the potential of e-V₂O₅ for applications to aqueous batteries, but also provides a surface reconstruction strategy for structural engineering of vanadium oxides with boosted ammonium-ion storage properties.