Dislocation Effect\nBoosting the Electrochemical Properties\nof Prussian Blue Analogues for 2.6 V High-Voltage Aqueous Zinc-Based\nBatteries

Prussian blue analogues (PBAs) have attracted increasing\nattention\nin aqueous zinc-based batteries (AZBs) with the advantages of an open\nframework, adjustable redox potential, and easy synthesis. However,\nthey exhibited a low specific capacity and a poor cycle performance.\nIn this work, crystalline potassium iron hexacyanoferrate (FeHCF)\nwith dislocation was designed and prepared by a poly(vinylpyrrolidone)\n(PVP) additive. The metastable state provided by PVP would cause an\nelectrostatic interaction between cyanogen and water molecules. The\nreduced force increases the steric resistance of the water molecules\nentering the crystal. The low content of crystal water in FeHCF is\nassociated with the formation of dislocation. The dislocation effect\neffectively improves the electrochemical reactivity and reaction kinetics\nof FeHCF. Thus, it presents a high reversible capacity of 131 mAh\ng<sup>–1</sup> with a superior capacity retention of 85% after\n550 cycles at 0.5 A g<sup>–1</sup>. When used as a cathode,\nthe AZBs display a high voltage of 2.6 V, a fast charging capability\n(<5 min), and a satisfactory cycle stability with a capacity retention\nof 82% after 400 cycles at 0.2 A g<sup>–1</sup> in decoupling\nelectrolytes. This work provides an effective strategy for the design\nof high-performance PBA-based cathodes for 2.6 V AZBs.