Intercalated K⁺ reinforces structural stability in vanadate for durable zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) present a highly attractive option with substantial potential for energy storage applications. However, issues such as the structural instability and slow zinc-ion diffusion of the cathode have hindered Zn//vanadium battery development. In this study, K + was chosen as a superior pre-insertion ion to form a novel layered potassium vanadate hydrate (K 1.44 V 8 O 20 ·1.8 H 2 O) cathode. Take advantage of the low electronegativity of K + , the M-O (Metal-Oxygen) bond in vanadium oxide cathode was dramatically enhanced. This leads to a significant enhancement in structural stability and a concurrent suppression of vanadium dissolution in the vanadium oxide cathode. Density functional theory (DFT) calculations were used to elucidate its superior Zn ion diffusion kinetics. The K 1.44 V 8 O 20 ·1.8 H 2 O exhibits outstanding cycling stability (specific capacity of 167.3 mAh g −1 after 9990 cycles at 6 A g −1 ) and excellent rate performance (78.64 % capacity retention after 10,000 cycles at 10 A g −1 ). This study proposes a viable strategy for the design of a stable vanadium oxide cathode.