Water molecules and oxygen-vacancy modulation of vanadium pentoxide with fast kinetics toward ultrahigh power density and durable flexible all-solid-state zinc ion battery

Aqueous zinc ion battery (ZIB) with many virtues such as high safety, cost-effective, and good environmental compatibility is a large-scale energy storage technology with great application potential. Nevertheless, its application is severely hindered by the slow diffusion of zinc ions in desirable cathode materials. Herein, a technique of water-incorporation coupled with oxygen-vacancy modulation is exploited to improve the zinc ions diffusion kinetics in vanadium pentoxide (V2O5) cathode for ZIB. The incorporated water molecules replace lattice oxygen in V2O5, and function as pillars to expand interlayer distance. So the structural stability can be enhanced, and the zinc ions diffusion kinetics might also be promoted during the repeated intercalation/deintercalation. Meanwhile, the lattice water molecules can effectively enhance conductivity due to the electronic density modulation effect. Consequently, the modulated V2O5 (H-V2O5) cathode behaves with superior rate capacity and stable durability, achieving 234 mA h g−1 over 9000 cycles even at 20 A g−1. Furthermore, a flexible all-solid-state (ASS) ZIB has been constructed, exhibiting an admirable energy density of 196.6 W h kg−1 and impressive power density of 20.4 kW kg−1 as well as excellent long-term lifespan. Importantly, the assembled flexible ASS ZIB would be able to work in a large temperature span (from −20 to 70 °C). Additionally, we also uncover the energy storage mechanism of the H-V2O5 electrode, offering a novel approach for creating high-kinetics cathodes for multivalent ion storage.