Background: Demands of rechargeable energy storage devices such as batteries are increasing. Potassium is cheap and abundant contrary to Li. Prussian blue and analogues PBAs are promising cathodes materials for K- ion batteries, because of facile synthesis and low cost. However, PB and close analogues (Prussian green and Prussian white) suffer from low coulombic efficiency and low cyclability owing to structure deficiency. We present here a facile synthesis dip-dry method at elevated temperature of Prussian yellow film cathode for aqueous potassium battery with Zn anode. The device exhibits a high specific capacity, coulombic efficiency and long cycling life with satisfactory charge/discharge behavior.
Method: Prussian yellow(PY) film was prepared as a thin film on ITO substrate by dip dry method from a solution mixture of Fe3+ (0.1M) and Fe(CN)-6 (0.1M) at (80°C). Precipitation time was fifteen minutes. Films where characterization by FTIR, TGA, XRD, EDS, SEM, CV and EIS. Batteries composed of PY cathode and zinc metal anode were tested in 0.1M KCl electrolyte.
Results: Battery gave OCV 1.9V with specific capacity of 142 mAh/g at rate of (~ 3C), with satisfactorily cycling ability up to 500 cycles & reversible charge/discharge behavior. Good crystal structure of PY film was demonstrated by several characterization methods e.g., FT-IR, TGA, XRD, EDS, SEM and electrochemical techniques. All showed good crystallinity quality of prepared PY films which demonstrate cathode qualities K cathode for K charge / discharge battery.
Conclusion: Prussian yellow film, one of Prussian blue close analogues prepared in a simple and very facile nonelectrical method can be used as a robust cathode with highly reversible redox reactions that enable this material to be used as a cathode in battery of potassium aqueous electrolyte with Zinc anode. Battery has a significant cycle life (~500 cycle) and satisfactory capacity of 142mAhg-1 at rate of (~3C) with efficiency retention of 82%.