Bio-inspired Polyionic Membrane for Long-lasting and Repeatable Electricity Harvesting from Moisture

Evaporation power generation (EPG), hailed as a promising clean power generation technology, has garnered significant attention. Nonetheless, achieving consistent and replicable performance of EPG remains a major challenge, hampering its practical application potential. Herein, we present the design of a tri-layered poly-ionic membrane (TL-PIM) inspired by transpiration processes in plants, that can not only continuously output electricity with an average voltage of ~0.6 V for over 8 consecutive days with a maximum power density of 1.6 µW cm−2, but can also be reused for at least 70 cycles (> 350 hours) with a stable voltage, demonstrating superior repeatability over most previous works. The excellent long-lasting and repeatable performance of EPG in the TL-PIM can be attributed to the stable nanochannels constructed by a hydrophilic polymer, 2D nanosheets, and poly-ionic liquids (PILs), where the bromide ions (Br-) in the PILs can shuttle back and forth selectively and efficiently during the power generation and discharge processes. More importantly, the TL-PIM can be integrated linearly to generate electricity within a wide range of temperatures and humidity, even outdoors, showcasing remarkable environmental adaptability. These findings on EPG indicate that the bio-inspired TL-PIM offers a promising venue for continuous and reproducible electricity generation by harnessing thermal energy from moisture, which holds significance for the sustainable utilization of EPG as a renewable energy source in the future.