High-Performance Double-Drive Water Evaporation-Induced Generator Operating Without Liquid Water Sources

Restricted electrical output and the heavy reliance on liquid water sources severely limit the further development of water evaporation-induced generators (WEGs) based on the inherently slow phase transition of water molecules. Here, inspired by the rolling logs to transport boulders, a double-drive WEG (DWEG) is developed, in which double ionic circulations and ion-electronic friction provide intensive horsepower and grip for energy capture. DWEGs applied in deionized water can continuously generate a high voltage of 1.13 V and a stable current of 10.54 µA (1.76 µA cm^-2) under ambient conditions (≈20 °C, ≈43% RH). In addition, benefiting from the high osmotic pressure and mechanical strength of ionized composite hydrogels, DWEGs can be directly plugged into soil with minimal water (as little as 12.5 wt.%) to generate electricity, eliminating the reliance on a liquid water source. Interestingly, a high electrical output (0.65 V, 0.89 µA) is sustained (>60 h) at low-temperature (e.g., -12 °C), overcoming the temporal and geographical restrictions of conventional WEGs in their practical applications.