We present a novel power-to-water (P2W) battery that can store electricity as thermal energy and discharge it as a heat source for hygroscopic solution desorption. The battery can work in two scenarios: atmospheric water harvesting (AWH) and dehumidification. The involvement of high-grade energy and sophisticated design enables better sorption kinetics and storage density. A proof-of-concept prototype verified the feasibility and achieved a record-breaking water production rate of more than 10.2 g (Ldevice h)−1. Also, the battery can achieve a round-trip efficiency of 90% for AWH and 68% for dehumidification in large-scale storage. The inexpensive storage medium contributes to a very low cost per energy (∼20 $ kWh–1) which means that P2W batteries excel in short- and long-duration storage. The long-term transient performance studies demonstrate impressive competitiveness over the traditional AWH and vapor-compression dehumidification systems. P2W provides new directions for the development of versatile, scalable, repeatable, and sustainable energy storage systems.
