Ambient Synthesis of Vanadium‐based Prussian Blue Analogues Nanocubes for High‐performance and Durable Aqueous Zinc‐ion Batteries with Eutectic Electrolytes

Abstract Prussian blue analogues (PBAs) have been widely studied in aqueous zinc‐ion batteries (AZIBs) due to the characteristics of large specific surface area, open aperture, and straightforward synthesis. In this work, vanadium‐based PBA nanocubes were firstly prepared using a mild in situ conversion strategy at room temperature without the protection of noble gas. Benefiting from the multiple‐redox active sites of V 3+ /V 4+ , V 4+ /V 5+ , and Fe 2+ /Fe 3+ , the cathode exhibited an excellent discharge specific capacity of 200 mAh g −1 in AZIBs, which is much higher than those of other metal‐based PBAs nanocubes. To further improve the long‐term cycling stability of the V‐PBA cathode, a high concentration water‐in‐salt electrolyte (4.5 M ZnSO 4 +3 M Zn(OTf) 2 ), and a water‐based eutectic electrolyte (5.55 M glucose+3 M Zn(OTf) 2 ) were designed to successfully inhibit the dissolution of vanadium and improve the deposition of Zn 2+ onto the zinc anode. More importantly, the assembled AZIBs maintained 55 % of their highest discharge specific capacity even after 10000 cycles at 10 A g −1 with superior rate capability. This study provides a new strategy for the preparation of pure PBA nanostructures and a new direction for enhancing the long‐term cycling stability of PBA‐based AZIBs at high current densities for industrialization prospects.