Layered Potassium Vanadate K0.5V2O5 as a Robust Cathode Material for Aqueous Zinc‐Ion Batteries

Abstract Layered vanadates are promising cathode materials for aqueous zinc‐ion batteries (AZIBs). Herein, a layered potassium vanadate K 0.5 V 2 O 5 is reported as a promising cathode material for AZIBs. It provides a high reversible capacity of 471.1 mAh g −1 with unprecedent cycle life at a harsh low rate of 0.21 C (90.2% capacity retention after 400 cycles, running time 150 days), remarkable rate capability and decent long‐term cycling stability (no capacity decay after 1700 cycles). According to a series of tests, it is revealed that the energy storage mechanism of K 0.5 V 2 O 5 involves initial extraction of K + followed by subsequent (de)intercalation of Zn 2+ /H + , in which the concomitant structure change and chemical state transition of vanadium possess high reversibility. Moreover, K 0.5 V 2 O 5 exhibits rapid Zn 2+ /H + ion diffusion, favoring its rate capability. Additionally, K 0.5 V 2 O 5 also demonstrates excellent low‐temperature adaptability, which can operate stably at −30 °C. The excellent electrochemical performance, facile preparation, and low cost of K 0.5 V 2 O 5 promise it as an attractive cathode candidate for practical AZIBs.