Oxygen Defects Engineering of VO2•xH2O Nanosheets via In Situ Polypyrrole Polymerization for Efficient Aqueous Zinc Ion Storage

What has been a crucial demand is that designing mighty cathode materials for aqueous zinc-ion batteries (AZIBs), which are vigorous alternative devices for large-scale energy storage by means of their high safety and low cost. Herein, a facile strategy is designed that combines oxygen defect engineering with polymer coating in a synergistic action. As an example, the oxygen-deficient hydrate vanadium dioxide with polypyrrole coating (O-d-HVO@PPy) is synthesized via a one-step hydrothermal method in which introducing oxygen vacancy in HVO is simultaneously realized during the in situ polymerization. Such a desirable material adjusts the surface adsorption and internal diffusion of Zn2+ demonstrated by electrochemical characterization and theoretical calculation results. Moreover, it also utilizes conductive polymer coating to improve electrical conductivity and suppress cathode dissolution. Therefore, the O-d-HVO@PPy electrode delivers a preferable reversible capacity (337 mAh g(-1) at 0.2 A g(-1)) with an impressive energy density of 228 Wh kg(-1) and stable long cycle life. This enlightened design opens up a new modus operandi toward superior cathode materials for advanced AZIBs.

Automated summary

A new cathode material, oxygen-deficient hydrate vanadium dioxide with polypyrrole coating, has been successfully designed for aqueous zinc-ion batteries, demonstrating improved surface adsorption and internal diffusion of Zn2+ as well as enhanced electrical conductivity and suppressed cathode dissolution. This material shows promising performance in terms of reversible capacity, energy density, and long cycle life, paving the way for advanced AZIBs.