High adhesion hydrogel electrolytes enhanced by multifunctional group polymer enable high performance of flexible zinc-air batteries in wide temperature range

With the development of flexible wearable electronic products, the demand for energy storage devices with high energy density and light weight is increasing, and flexible zinc-air batteries (ZABs) are expected to become a new generation of matching power source for wearable devices. The synthesis of hydrogel electrolytes with high ionic conductivity, excellent mechanical properties and strong alkali resistance is the key to the assembly of flexible ZABs. However, the conventional hydrogel electrolytes are very easy to detach from the electrode after being applied to the flexible ZABs through multiple bending, high temperature and low temperature environments, resulting in a large interfacial resistance, which limits the application of the batteries. Herein, a multifunctional group polymer, carboxymethyl chitosan (CMCS) is cross-linked with the copolymer of acrylamide (AM) and sodium acrylate (ANa) to form a high-performance double-network hydrogel with a high ionic conductivity of 145.63 mS cm−1. The optimal hydrogel electrolyte exhibits an admirable power density of 120.87 mW cm−2 when applying to a flexible ZABs. Meanwhile, the battery not only show remarkable electrochemical performance over a wide temperature range (−20 to 80 °C), but also possess good stability and practicality under various extreme conditions. This work opens up new ideas for the development of hydrogel electrolytes with high adhesion and performance, and provides new strategies for the research of flexible batteries with adaptability to extreme conditions.