Heat activated VO₂(R) cathodes for high-performance aqueous zinc ion batteries

We introduce a novel approach for design and production of vanadium dioxide (VO 2 ) cathodes activated by heat, specifically tailored for use in aqueous zinc-ion batteries (ZIBs). Our cathodes exhibit distinctive metal-insulator transition (MIT) characterized by the shift between monoclinic (M) and tetragonal rutile (R) phases. The employment of an aqueous electrolyte in ZIBs enables successful operation of VO 2 cathodes, showcasing phase transition and enhanced electrochemical performance above a readily attainable temperature of approximately 68 degrees C. The MIT feature enhances the charge transfer properties at electrode-electrolyte interfaces, resulting in notable improvements in specific capacity and energy densities. Fabricated VO 2 (M) cathodes underwent heattriggered transformation to VO 2 (R), resulting in a remarkable increase (400 %) in capacity. At 0.1 A g - 1 , VO 2 (R) cathodes show specific capacity of 354.6 mAh g - 1 , yielding an impressive energy density of 461.0 Wh kg - 1 for aqueous ZIBs. This exceptional performance can be attributed to abrupt change in electrical conductivity upon thermal activation of MIT. This work underscores pivotal role of thermally activated MIT in finely tuning electrochemical performance of energy storage systems, prospecting a promising avenue for further advancements.