Novel porous thermosensitive gel electrolytes for wearable thermo-electrochemical cells

Thermo-electrochemical cells (TECs) represent an efficient and low-cost heat-harvesting device that can directly convert human body heat energy into electricity. However, the flexible, solid-state gelled electrolytes used in wearable thermocell devices suffer from poor mass transport of electrolyte. Here, a novel porous gel is developed via sodium acetate (NaAc) templates and freeze-drying treatment that is applied in p-type gelled electrolyte: poly-acrylamide (PAM) K-3/4[Fe(CN)(6)] and integrated into platinum (Pt) electrodes for wearable devices. Moreover, the guanidinium ([Gdm]+) is initially introduced into gelled electrolytes, and the p-type cell effectively boosts the maximum power density from 4.01 to 7.68 mW m(-2) at delta T = 10 ?, and exhibits a quick thermosensitive response under a broad temperature range (15 - 55 ?), which is sufficient for working conditions of wearable devices. The optimised porous gel host was also utilized in series with an n-type: PAM-FeCl2/3-HCl gelled electrolyte. The multiple thermocells (12 pairs) were further fabricated into a device by alternating p-and n-type cells in series. This device was found to output nearly 0.23 V at delta T = 10 ?, and was manufactured into a flexible wearable device that was demonstrated to successfully harvest human body heat by both charging a supercapacitor (100 mF), and illuminating an LED, demonstrating the potential of actual application of our n-p type in series devices.

Automated summary

This study developed a novel porous gel for wearable thermocell devices, which improved the mass transport of electrolyte. The introduction of guanidinium effectively enhanced the power density and thermosensitive response of the cell. By assembling p-type and n-type cells in series, a flexible wearable device was created that successfully harvested human body heat to charge a supercapacitor and illuminate an LED.