2D Amorphous V2O5/Graphene Heterostructures for High‐Safety Aqueous Zn‐Ion Batteries with Unprecedented Capacity and Ultrahigh Rate Capability

Abstract Rechargeable aqueous zinc‐ion batteries (ZIBs) are appealing due to their high safety, zinc abundance, and low cost. However, developing suitable cathode materials remains a great challenge. Herein, a novel 2D heterostructure of ultrathin amorphous vanadium pentoxide uniformly grown on graphene (A‐V 2 O 5 /G) with a very short ion diffusion pathway, abundant active sites, high electrical conductivity, and exceptional structural stability, is demonstrated for highly reversible aqueous ZIBs (A‐V 2 O 5 /G‐ZIBs), coupling with unprecedented high capacity, rate capability, long‐term cyclability, and excellent safety. As a result, 2D A‐V 2 O 5 /G heterostructures for stacked ZIBs at 0.1 A g −1 display an ultrahigh capacity of 489 mAh g −1 , outperforming all reported ZIBs, with an admirable rate capability of 123 mAh g −1 even at 70 A g −1 . Furthermore, the new‐concept prototype planar miniaturized zinc‐ion microbatteries (A‐V 2 O 5 /G‐ZIMBs), demonstrate a high volumetric capacity of 20 mAh cm −3 at 1 mA cm −2 , long cyclability; holding high capacity retention of 80% after 3500 cycles, and in‐series integration, demonstrative of great potential for highly‐safe microsized power sources. Therefore, the exploration of such 2D heterostructure materials with strong synergy is a reliable strategy for developing safe and high‐performance energy storage devices.