A flexible evaporation-induced generator enhanced by water-ion-temperature multifield coupling

Evaporation-induced generators (EIGs) have emerged as a focal point in environmental energy harvesting research, with notable progress in boosting output power and elucidating their underlying mechanics. However, their output power remains insufficient for wearable applications, and the coupling mechanisms involved are not yet fully understood. In this study, a flexible EIG was designed to further investigate these challenges. The device employs an asymmetric configuration consisting of a porous carbon fabric@PEDOT:PSS hydrophilic top electrode, a carbon composite material/copper foil hydrophobic bottom electrode and a semi-interpenetrating MC-PAM-PPy (MPP) hydrogel functional layer. Under atmospheric conditions, the device achieves a peak power density of 0.79 mW/cm 2 , attributed to its asymmetric water evaporation interface and the hydrogel layer rich in water, ions and temperature transfer effects, which together exploit the three gradient effects of ‘water-ion-temperature’. This study clarifies three synergistic ‘mass-charge-heat’ transfer effects: asymmetric water evaporation (mass) drives ion migration (charge) while simultaneously inducing thermal conduction (heat), providing valuable insights into enhancing device performance and understanding its power-generation mechanism. In addition, the device demonstrates excellent flexibility, making it well-suited for wearable applications and significantly broadening the potential use of EIGs. • An evaporation-induced generator (EIG) is fabricated with high output power. • The EIG utilizes water–ion–temperature gradient for mass, charge, and heat transfer. • The EIG adapts to the dynamic needs of the human body as a wearable device.