Hydrogel-Based Moisture Electric Generator with High Output Performance Induced by Proton Hopping

Abstract

The development of harnessing energy from surrounding humidity has been impeded by obstacles such as ambiguous ion migration mechanism and the restricted electrical output of devices designed to generate power from moisture. Herein, a novel hygroscopic network is presented that enhances ion migration by employing a random copolymerization of acrylamide (AAm) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS). This method strategically positions sulfonic acid groups within hydrogels, which can release protons, in the presence of LiCl. Both experimental data and molecular dynamic simulations indicate that ion migration primarily occurs through a proton hopping mechanism, protons are released from the ─SO₃H and interact with adjacent confined water molecules, creating a network that facilitates swift proton migration along hydrogen-bonded chains. The developed single sulfonic acid side chain@hydrogel-based moisture-electric generator (SHMEG) exhibits a sustained open-circuit voltage (V_oc) of 0.89 V and a current density of 173 µA cm⁻² for over 1400 h. Additionally, the SHMEG's scalability allows it to be connected in series or parallel, which provides adaptability and lightness. These features render the SHMEG suitable for powering a variety of commercial devices, such as mobile phone, health monitoring sensors and nighttime illumination, making it a promising, high power, and environmentally friendly energy solution.