Ionic hydrogel for efficient and scalable moisture-electric generation

Abstract

The progress of spontaneous energy generation from ubiquitous moisture has been hindered the low output current and intermittent operating voltage of the moisture-electric generators. Herein we develop a novel and efficient ionic hydrogel moisture-electric generator (IHMEG) by rational combination of poly(vinyl alcohol), phytic acid and glycerol-water binary solvent. Thanks to the synergistic effect of notable moisture-absorption capability and fast ion transport capability in the ionic hydrogel network, a single IHMEG unit of 0.25 cm2 can continuously generate direct-current electricity with a constant open-circuit voltage of ∼0.8 V for over 1000 hours, a high short-current density of 0.24 mA·cm–2 and power density of up to 35 μW·cm–2. Of great importance is that large-scale integration of IHMEG units can be readily accomplished to offer a device with voltage up to 210 V, capable of directly driving numerous commercial electronics, including electronic ink screen, metal electrodeposition setup and light-emitting-diode arrays. Such prominent performance is mainly attributed to the enhanced moisture-liberated proton diffusion proved by experimental observation and theoretical analysis. The ionic hydrogel with high cost-efficiency, easy-to-scaleup fabrication and high power-output opens a brand-new perspective to develop a green, versatile and efficient power source for Internet-of-Things and wearable electronics.