Harvesting Thermal Energy and Freshwater from Air through Sorption Thermal Battery Enabled by Polyzwitterionic Gel

Utilizing hygroscopic materials for water sorption and desorption from the atmosphere involves the capture, storage, and release of both water and heat. Herein, we introduce a design framework tailored for salt-embedded composite hygroscopic gels and analyze the mass-energy flow during sorption–desorption processes. Through this framework, we develop a hygroscopic gel composed of zwitterionic and nonionic chains, which exhibits a controlled salting-in effect, leading to stable salt retention, high energy density, and water sorption capacity. When integrated into a multifunctional device with three distinct flow paths, it achieves an impressive thermal storage energy density of 7779.6 kJ·kggel–1, with a temperature increase ranging from 3.6–13 °C during heat release, and efficient heat storage within 90 min under mild heating at 61 °C. In water harvesting mode, the device yields a liquid water productivity of 0.97 kgwater·kggel–1. This research highlights the potential of atmospheric water sorption for simultaneous thermal energy storage and water generation.