Voltage and power enhancement of hygroelectric cell using self-discharge suppression by polyethylene glycol addition


 Hygroelectric cell (HEC) is an energy harvester that generates electricity utilizing humidity changes in the air, based on a concentration cell with a deliquescent salt solution. The performance of HEC is limited by self-discharge derived from water permeation through a cation-exchange membrane. In this work, we report on the voltage and power enhancement of HEC via self-discharge suppression by adding polyethylene glycol (PEG) to the electrolyte solution of HEC. At maximum, the addition of 2 wt% PEG4000 improved the peak-to-peak voltage under the humidity changes between 30–90%RH to 128 mV from 48 mV, and the addition of 5 wt% PEG400 improved the output power to 36.7 μW (6.4 μW/cm2) from 4.4 μW (0.8 μW/cm2). Also, the effectiveness of PEG addition was demonstrated in a real outdoor environment.