Long‐Lasting and High‐Power‐Density Yarn‐Based Moisture‐Enabled Electric Generator for Self‐powered Electronic Textiles

1D moisture-enabled electric generators (MEGs) hold great promise for powering electronic textiles, but their current limitations in power output and operational duration restrict their application in wearable technology. This study introduces a high-performance yarn-based moisture-enabled electric generator (YMEG), which comprises a carbon-fiber core, a cotton yarn active layer with a radial gradient of poly(4-styrensulfonic acid) and poly(vinyl alcohol) (PSSA/PVA), and an aluminum wire as the outer electrode. The unique design maintains a persistent moisture gradient between the interior and exterior electrodes, enhancing performance through the continuous proton diffusion from PSSA and Al³⁺ ions from the aluminum wire. The optimized 5-cm-long YMEG delivers an open-circuit voltage of 1.35 V and a short-circuit current density of 460 µA cm^-2, sustaining over 300 µA cm^-2 for more than 5 h. When woven into a 1 m long yarn containing 95 YMEGs, it generates 101.0 V at 60% relative humidity. Additionally, a configuration of 420 YMEGs connected in series and parallel can power a 1 W LED and a 40 mW motor. This innovative YMEG design paves the way for self-powered electronic textiles such as warning vests and headbands, capable of harnessing insensible sweat for energy.