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

Abstract

Abstract A hygroelectric cell (HEC) is an energy harvester that generates electricity by utilizing changes in the air humidity based on a concentration cell with a deliquescent salt solution. The performance of HEC is limited by the 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 a maximum, the addition of 2 wt% PEG4000 improved the peak-to-peak voltage under the humidity changes between 30% and 90%RH to 128 from 48 mV and the addition of 5 wt% PEG400 improved the output power to 36.7 μW (6.4 μW cm−2) from 4.4 μW (0.8 μW cm−2). In addition, the effectiveness of the addition of PEG was demonstrated in a natural outdoor environment.