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 environ-mental 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 inter-layer 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 ℃).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.