Phenolphthalein-Modified Multivalent Vanadium Oxide: Harnessing Oxygen Vacancies and Hydrophobicity for Improved Aqueous Zinc-Ion Battery Performance

Vanadium-based compounds are promising candidates as cathode materials for aqueous zinc-ion batteries (ZIBs) due to their open crystal structure and high theoretical specific capacity. However, their dissolution problems in aqueous electrolytes lead to severe fast capacity decay, hindering the further development of ZIBs. Herein, a multivalent vanadium oxide (VOH@phph) with phenolphthalein coating was synthesized via a facile strategy under room temperature. The natural hydrophobicity of the coated phenolphthalein reduces direct interaction between the material and water molecules, restraining vanadium dissolution and effectively enhancing the cyclic stability of the material. Moreover, the introduction of phenolphthalein results in increased oxygen vacancies, thereby significantly shortening the diffusion path of Zn2+ ions and consequently improving the rate performance of VOH@phph. Notably, at a current density of 2 A g–1, the battery featuring VOH@phph as the cathode demonstrates a specific capacity of 294.37 mAh g–1 and maintains a retention rate of 96.82% after 1000 cycles.