Layered Potassium Vanadate K <sub>0.5</sub> V <sub>2</sub> O <sub>5</sub> as a Robust Cathode Material for Aqueous Zinc‐Ion Batteries
Leqing Deng, Lilin Chen, Shuaiqi Wang, Siying Wang, Qingsong Hu, Qiangwei Li, Lidong Wang
Abstract
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.