Multi-Functional Hydrogels for Flexible Zinc-Based Batteries Working under Extreme Conditions

Zinc-based batteries are potential candidates for flexible energy storage due to their high capacity, low cost, and intrinsic safety. Hydrogel electrolytes with saturated aqueous solvents can provide remarkable electrochemical performance while retaining satisfactory flexibility for zinc-based batteries. The past decades have witnessed their fast growth. However, the study of zinc-based batteries with hydrogel electrolytes under extreme conditions is still in the early stages and many technical issues remain to be addressed. In this review, the physical and chemical properties of hydrogel electrolytes are discussed for application in zinc-based batteries. Strategies towards hydrogel electrolytes and flexible zinc-based batteries under extremely high/low temperatures or under deformation conditions and their behaviors are reviewed and analyzed. Moreover, design strategies for all-around hydrogel electrolyte that are appropriate for use in all these extreme conditions are proposed. A perspective discussing the challenges and future directions of hydrogel electrolyte for zinc-based batteries is also provided.