Synchronous dual‐modification strategy of K ⁺ intercalation and CrO _<i>x</i> coating enabling durable zinc‐ion storage in vanadium oxide

Abstract The diverse valence and spatial structure endow vanadium oxides with significant potential in the field of aqueous zinc ion batteries (AZIBs). Although the conventional ion doping method mitigates the intrinsically sluggish kinetics, it exacerbates the erosion of Zn 2+ /H + and free water within the lattice structure, leading to inferior structural stability and capacity fading. Herein, a synchronous dual‐modification strategy is introduced to improve the electrochemical performance of the V 6 O 13 cathode through an ingenious hydrolysis process involving K 2 Cr 2 O 7 . Experimental and calculated results demonstrate that the coating layer formed by chromium oxide supports the structural firmness and strengthens the interfacial chemistry, based on increased electrochemical activity by K + intercalation. Consequently, the optimized sample delivers a capacity of 418 mAh g −1 at 0.1 A g −1 , and excellent cyclic stability of 205 mAh g −1 after 6000 cycles at 10 A g −1 . It is fully charged at a small current of 0.5 A g −1 to maintain a reversible capacity of 346 mAh g −1 after 72 h in an open circuit state, and there is no obvious capacity decay, highlighting the crucial protective effect of the inactive coating layer. This work presents a straightforward and reliable approach to effectively harmonize the relationship between activity and structural stability for advanced AZIBs cathode.