Proposed are Prussian blue analogue hosts with ordered and continuous channels, and electrocatalytic functionality with open Co and Fe species, which facilitate maximum I2 utilization efficiency and direct I2 to I− conversion kinetics of the I2 reduction reaction, and free up 1/3 I− from I3−. Co[Co1/4Fe3/4(CN)6] exhibits a low energy barrier (0.47 kJ mol−1) and low Tafel slope (76.74 mV dec−1). Accordingly, the Co[Co1/4Fe3/4(CN)6]/I2//Zn battery delivers a capacity of 236.8 mAh g−1 at 0.1 A g−1 and a rate performance with 151.4 mAh g−1 achieved even at 20 A g−1. The battery delivers both high energy density and high-power density of 305.5 Wh kg−1 and 109.1 kW kg−1, higher than I2//Zn batteries reported to date. Furthermore, solid-state flexible batteries were constructed. A 100 mAh high capacity solid-state I2//Zn battery is demonstrated with excellent cycling performance of 81.2 % capacity retained after 400 cycles.
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