High-Output, Stretchable, Moisture-Electric Generator Enabled by Tailored Acrylic Acid/Choline Chloride Eutectogel

Moisture-electric generation (MEG), a technology that captures chemical energy from environmental moisture and converts it into sustainable electricity, has attracted significant attention in the field of flexible wearable electronics. However, existing MEG systems still face critical challenges such as low output voltage, poor current stability, and insufficient mechanical properties of materials. Herein, a poly(acrylic acid) (PAA)/choline chloride (ChCl) eutectogels (PA-C) with a "covalent bond-ion pair-hydrogen bond" triple network structure was prepared via ultraviolet photopolymerization by constructing an acrylic acid (AA)/ChCl deep eutectic solvent (DES). Specifically, the cross-linking agent N,N'-methylenebis(acrylamide) (MBA) forms covalent cross-links with AA to provide a rigid framework for PA-C. Meanwhile, hydrogen bonds between PAA chains, as well as ion pairs and hydrogen bonds between PAA and ChCl, form a reversible physical cross-linking network. These networks synergistically endow PA-C with excellent hydrophilicity and mechanical properties. The effect of the molar ratio of AA to ChCl on the microstructure and properties of PA-C was systematically investigated. The results show that under an appropriate AA/ChCl molar ratio, PA-C exhibits a tensile strength of 4.92 MPa and an elongation at break of 633% simultaneously. The MEG developed based on PA-C achieves a high ionic conductivity of 0.54 S m^-1 under relative humidity (RH) of 99%. A single MEG device can deliver an open-circuit voltage (V_oc) of 1.28 V and a short-circuit current (I_sc) of 2.20 mA, with a maximum power density of 90 μW cm^-2. Through series and parallel integration, the voltage and current can be flexibly adjusted, enabling direct power supply to light-emitting diodes (LEDs) and low-power devices. This study not only provides a material system for the design of high-performance MEG devices but also opens up an avenue for the development of efficient, scalable, and flexible multifunctional power sources.