Preparation and Characterization of Starch-Based Hydrogel Electrolyte Membrane for Quasi-Solid-State Rechargeable Alkaline Zinc Battery

The development of hydrogel electrolytes is a crucial and urgent task to achieve reliable rechargeable alkaline zinc batteries. We have successfully prepared a starch-based hydrogel electrolyte membrane (SHEM) that holds a (4 mol dm−3 (= M) KOH + 0.3 M ZnO) aqueous solution. The prepared SHEM was so flexible that it could be stretched and bent freely, and showed high ionic conductivity comparable to that of the alkaline aqueous solution. A pouch-type Zn/Zn cell with SHEM did not short-circuit for more than 24 h, and uniform Zn deposition without dendritic growth was confirmed in scanning electron microscope images. In the charge-discharge cycle test of a pouch-type Zn/MnO2 cell with SHEM, it was demonstrated that SHEM can fully function as an electrolyte for quasi-solid-state rechargeable alkaline zinc batteries.