Effect of phosphoric acid-doped polybenzimidazole membranes on the performance of H+-ion concentration cell

H+-ion concentration cell, which can harvest thermal energy to generate electricity by hydrogen concentration difference principle with a fuel cell structure, is an innovative thermoelectric conversion device. In this system, phosphoric acid-doped polybenzimidazole (PA-doped PBI) membrane is a key component influencing the power generation performance of the cell. Herein, 30, 45, 60, 75, and 90 mu m thick PBI membranes are successfully synthesized and doped with phosphoric acid. To achieve a good compromise between the proton conductivity and durability, the properties of PA-doped PBI membranes are experimentally evaluated to clarify the effect of the acid doping time and membrane thickness on cell performance. The results indicate that the higher the acid doping level, the worse the dimensional stability of the membrane. Also the thinner the PBI membrane, the smaller the membrane resistance to ions motion, while the poorer the stability. Upon reaction at 170 degrees C, this cell can boast a power density from 3.0 to 8.0 W.m(-2), which results in a thermoelectric conversion efficiency of 5.97-14.32%. This study potentially boosts the practical application of thermal-to-electrical conversion technology. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

H+-ion concentration cell with a fuel cell structure can convert thermal energy to electricity based on hydrogen concentration difference principle. Phosphoric acid-doped polybenzimidazole (PA-doped PBI) membrane, a key component, affects the power generation performance. Experimental evaluation shows that higher acid doping levels reduce dimensional stability, while thinner membranes have lower resistance to ion motion but poorer stability. Power densities of 3.0 to 8.0 W.m(-2) and thermoelectric conversion efficiencies of 5.97-14.32% can be achieved at 170 degrees C, promoting the practical application of thermal-to-electrical conversion technology.