Phytic Acid Customized Hydrogel Polymer Electrolyte and Prussian Blue Analogue Cathode Material for Rechargeable Zinc Metal Hydrogel Batteries

Abstract

Zinc anode deterioration in aqueous electrolytes, and Zn dendrite growth is a major concern in the operation of aqueous rechargeable Zn metal batteries (AZMBs). To tackle this, the replacement of aqueous electrolytes with a zinc hydrogel polymer electrolyte (ZHPE) is presented in this study. This method involves structural modifications of the ZHPE by phytic acid through an ultraviolet (UV) light‐induced photopolymerization process. The high membrane flexibility, high ionic conductivity (0.085 S cm−1), improved zinc corrosion overpotential, and enhanced electrochemical stability value of ≈2.3 V versus Zn|Zn2+ show the great potential of ZHPE as an ideal gel electrolyte for rechargeable zinc metal hydrogel batteries (ZMHBs). This is the first time that the dominating effect of chelation of phytic acid with M2+ center over H‐bonding with water is described to tune the gel electrolyte properties for battery applications. The ZHPE shows ultra‐high stability over 360 h with a capacity of 0.50 mAh cm−2 with dendrite‐free plating/stripping in Zn||Zn symmetric cell. The fabrication of the ZMHB with a high‐voltage zinc hexacyanoferrate (ZHF) cathode shows a high‐average voltage of ≈1.6 V and a comparable capacity output of 63 mAh g−1 at 0.10 A g−1 of the current rate validating the potential application of ZHPE.