Covalently Cross-Linked Supramolecular-Polymer Dual-Network Hydrogel with High Ionic Conductivity and Interfacial Adhesion for Wide Temperature-Tolerant Flexible Zinc–Air Batteries

Flexible zinc–air batteries (ZABs) have attracted attention because of their intrinsic flexibility, high energy density, and excellent safety performance. However, the hydrogel electrolyte in ZABs usually suffers from shortcomings such as unsatisfactory tensile properties, low ionic conductivity, and poor water retention. Herein, a supramolecular-polymer dual-network hydrogel (G-PBA/PAAm SPDH) with excellent stretchability (>1000%) is prepared by combining a covalent self-assembled guanosine–phenylboronic acid tetramer supramolecular (G-PBA) network with a polyacrylamide (PAAm) network. What is more, the KOH (6 M)-filled G-PBA/PAAm SPDH shows remarkable freezing resistance (completely transparent at −40 °C), superior low- and high-temperature ionic conductivity (186 mS cm–1 at −40 °C and 195 mS cm–1 at 40 °C), good interfacial adhesion, and a satisfactory water retention rate of 70.06% after exposure to room temperature for 1 week. All these excellent properties strongly satisfy the application of G-PBA/PAAm SPDH as a multifunctional hydrogel electrolyte for flexible ZAB. As a result, the flexible ZAB assembled with the G-PBA/PAAm SPDH electrolyte can resist bending at different angles, maintain good electrochemical stability, and reach a high specific capacity (618 mA h gZn–1 at −40 °C and 680 mA h gZn–1 at 40 °C).