ZnO-modulated interfacial and hydrogen-bond networks for wide-temperature flexible Zn–air batteries

Developing hydrogel electrolytes with high ionic conductivity, mechanical stability, and wide-temperature adaptability is crucial for flexible Zn–air batteries. However, conventional gels suffer from high free-water activity, poor interfacial stability, and uncontrolled Zn deposition, severely limiting cycling life and low-temperature performance. This work constructs a PAA-KOH-ZnO composite hydrogel electrolyte by incorporating ZnO nanospheres. ZnO interacts with –COO- groups on the polymer chains, enhancing hydrogen bonding and reducing water mobility, as confirmed by theoretical calculations and hydrogen-bond analysis, thereby suppressing the hydrogen evolution reaction. The resulting gel achieves an ionic conductivity of 303 mS cm-1 and a water retention of 81.5%, and it promotes uniform Zn deposition with a preferential (002) texture. The flexible Zn–air battery assembled with this electrolyte delivers a peak power density of 126.7 mW cm-2, a specific capacity of 789.39 mAh g-1, and a cycling life of 165 h at room temperature. Moreover, the strengthened intermolecular interactions effectively mitigate low-temperature freezing and high-temperature water loss, enabling stable operation from –40 ℃ to 40 ℃ and a cycling life of 403 h at –40 °C. This work offers a new strategy for designing wide-temperature, long-lifespan gel electrolytes for flexible Zn–air batteries.