Revealing the impacts of oxygen defects on Zn2+ storage performance in V2O5

Vanadium pentoxide (V2O5) featured with open-framework structure and various oxidation states is regarded as the most promising cathode of aqueous zinc-ion batteries (ZIBs), whereas sluggish Zn2+ diffusion kinetics and poor structural stability plague its further application. Herein, the oxygen defects have been introduced into V2O5 (V2O5-O-d), the experimental studies and first-principles calculations reveal the oxygen defects can enlarge the interlayer spacing (7.58 angstrom) and significantly lower the Zn2+ diffusion energy barrier (0.72 eV), leading to favorable Zn2+ migration path and fast reactive kinetics. Moreover, a narrower bandgap (0.45 eV) and lower charge transfer resistance are obtained in V2O5-O-d, thus accelerating the electron transportation and improving the Zn2+ storage performance (427.3 mAh/g at 0.1 A/g). In addition, the internal structure of V2O5 is well-maintained owing to the greatly reduced formation energy of V2O5-O-d (55.04 eV), contributing to outstanding cycling stability (92.1% after 5,000 cycles at 20 A/g), outperforming numerous reported cathodes. Moreover, the pouch cell with V2O5-O-d delivers admirable electrochemical performance and modular integration capabilities, suggestive of its excellent practical viability. Therefore, this research highlights the great potential of oxygen defects in designing advanced electrodes and offers a guideline for exploring the working mechanism of defective electrode materials. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Introducing oxygen defects into vanadium pentoxide can significantly enhance the performance of zinc-ion batteries, including increasing interlayer spacing, lowering diffusion energy barriers, improving electron transport and storage capabilities, and enhancing cycling stability.