A water-anchored hydrogel with high water retention for wide-temperature zinc-air batteries

An ideal hydrogel should possess excellent water retention and broad temperature adaptability, which is crucial for its application in flexible electronic devices. However, most existing hydrogels exhibit significant performance degradation under extreme temperature conditions, particularly freezing at low temperatures and water evaporation at high temperatures. Here, we design a water-anchored hydrogel through ultraconcentrated salts, enabling water molecules closely connected with anions and cations in the hydrogel at extreme temperatures. This transformation converts water molecules into bound water, anchoring moisture within the hydrogel network. PAZ-HS exhibits a maximum tensile strain of over 600% while maintaining flexibility over a wide temperature range. In low-temperature environments, zinc-air batteries based on PAZ-HS hydrogels have a cycle life exceeding 670 h. Even at extreme temperatures of −80 °C and 100 °C, batteries assembled with this hydrogel consistently light LED with stable performance, demonstrating exceptional capabilities. Overall, this work proposes a multifunctional hydrogel preparation strategy with wide temperature adaptability, paving the way for flexible electronic devices in low-temperature environments.