A hydrogel-based moist-electric generator with superior energy output and environmental adaptability

Abstract

Harvesting energy from ubiquitous moisture has emerged as a promising way to collect energy irrespective of location and time. However, the electrical output of moist-electric generators (MEGs) is currently insufficient for practical applications. In this study, a highly efficient electricity-generating film was constructed by combining silicon dioxide (SiO2) nanofibers, sodium alginate (SA) and reduced graphene oxide (rGO) matrix impregnated with calcium chloride. The resulting SA–SiO2–rGO (SSG) film demonstrates a strong moisture-adsorption ability of 1.6 g/g at 80 % RH and 30 °C, and a relatively high ionic conductivity of 1.46 S m-1. The SSG film's strong moisture-adsorption capacity allows rapid ion dissociation, and its excellent electrical conductivity enhances ion migration. Thus, a single centimeter-sized device generates an open-circuit voltage (Voc) of up to ∼0.6 V and a short-circuit current (Isc) of ∼2.24 mA (0.14 mA cm−2). This short-circuit current is more than 10 times those of most reported MEGs. Moreover, an SSG-film-based MEG maintains a voltage output of ∼0.6 V over rather wide ranges of temperature (0–40 °C) and relative humidity (20 %–80 %), demonstrating superior environmental adaptability. In summary, this study provides fresh insights into the design of high-performance composite materials for efficient moist-electric energy conversion.