In-situ polymerization of polypyrrole on Prussian blue analogue for high capacity and flexible zinc-ion batteries

Prussian blue analogues (PBAs) have been considered as promising cathode materials for zinc-ion batteries. However, severe capacity decay issues hamper their deployment. Herein, Mn-ion-substituted zinc hexacyanoferrate (MZHCF) cathode materials were coated with polypyrrole (PPy) by in situ polymerization. The prepared MZHCF@PPy composites have exhibited significant ionic absorption affinity and great structural stability. Benefiting from the PPy coating, the ZIBs based on MZHCF@PPy cathodes and a conductive poly(acrylamide) (PAAM) hydrogel electrode exhibit enhanced capacities, which reach a maximum value of 190.1 mAh g−1 at 0.5 A g−1, three times higher than that of the device based on MZHCF electrodes. The flexible ZIBs not only present outstanding cyclic performance but also retain stable energy storage capability under various deformations. The presented method is a promising technology for the practical application of rechargeable ZIBs with high safety and flexibility.