Ab initio investigation of ZnV2O4, ZnV2S4, and ZnV2Se4 as cathode materials for aqueous zinc-ion batteries

Zinc-ion batteries (ZIBs) employing aqueous electrolytes have emerged as one of the most promising alternatives to lithium-ion batteries (LIBs). Nonetheless, the development of ZIBs is hindered by the scarcity of cathode materials with suitable electrochemical properties. In this work, we investigate the unique properties of zinc vanadate oxide (ZnV2O4, ZVO) and zinc vanadate sulfide (ZnV2S4, ZVS) compounds as cathode materials, focusing on their crystal structures, electrochemical performance, spectroscopic features and potential applications in ZIBs. Additionally, we investigate a new cathode material, zinc vanadate selenide (ZnV2Se4, ZVSe), constructed by replacing sulfur with selenium in the ZVS cubic structure. Our findings reveal that these compounds exhibit distinct electronic and electrochemical properties, although they have similar magnetic properties due to the fact that vanadium has the same oxidation state in all three compounds. On average, ZVS stands out as the most promising candidate for ZIBs cathodes, followed by ZVO. ZVSe, shows lower electrochemical performance and also has the obvious drawback of being more costly than the sulfur- and oxygen-based compounds. Our theoretical results align closely with available experimental data, both for electrochemical properties as well as x-ray and photoelectron spectroscopy, where a comparison can be made.