Hygroscopic-Evaporative Generator for Multiform Energy Harvesting from Environment and Food Storage.

Abstract

Moisture-enabled electricity generation (MEG) has gained increasing attention in recent years. However, most current systems rely exclusively on ambient relative humidity, exhibiting low output power and limited operational stability under fluctuating environmental conditions. Inspired by the natural process of plant transpiration-which efficiently circulates water using environmental stimuli such as humidity, sunlight, and wind-this study reports a hygroscopic-evaporative generator (HEG) capable of constantly converting ambient moisture into electricity. The HEG consists of a Lithium-Cellulose-based hygroscopic layer rich in mobile Li⁺ ions and a high-surface-area evaporative layer. Electricity generation is driven by spontaneous water adsorption on one side and directional water evaporation on the other, establishing a Li⁺ ion flow across the device. A single HEG unit delivers a peak voltage exceeding 1.0 V, a peak current of 0.8 mA, and a maximum power density of 1.506 mW cm- 3. By harvesting supplemental solar and wind energy, the HEG exhibits enhanced power output and stable performance even under large day-night humidity fluctuations. Furthermore, the device effectively scavenges bio-moisture from fruit respiration, enabling the generation of 1.2-1.4 V and significantly prolonging fruit shelf life, underscoring its durability and practical relevance for real-world applications.