Recyclable biomacromolecular hydrogel electrolytes for Zn-based aqueous batteries

Metallic Zn-based aqueous batteries (ZABs) have re-emerged as promising candidates for large-scale energy storage.However, their commercialization is still hindered by challenges such as uncontrolled zinc dendrite growth, hydrogen evolution, and severe corrosion [1].Conventional liquid electrolytes, although simple, are particularly susceptible to these issues [2].To overcome these limitations, hydrogel polymer electrolytes (HPEs) have attracted growing interest.By suppressing free water activity, regulating Zn 2+ flux, and providing mechanical reinforcement against dendrites, HPEs can effectively mitigate these problems [3].In addition, HPEs prevent electrolyte leakage and can simultaneously serve as separators, thereby simplifying cell configuration and imparting flexibility to ZABs [4].However, the controllable fabrication of HPEs remains a significant challenge.Conventional hydrogels typically exhibit a trade-off between ionic conductivity and mechanical strength, excelling in one property at the expense of the other.Moreover, processing HPEs into thin films (<100 m), which is essential for energy-dense cells, is particularly difficult.Sustainability further complicates the issue, as most petroleum-derived HPEs are neither recyclable nor environmentally friendly.