A parametric analysis on PEFCs for high-temperature applications

Abstract

Polymer Electrolyte Fuel Cells (PEFCs) are an increasingly significant facet of modern renewable energy and transportation, providing an electrochemical method of energy generation with high power density, thermal properties, and efficiency. PEFCs tend to increase in efficiency as temperature increases but detrimental effects begin to occur, including membrane degradation and dehydration. These effects are unfavourable in the design of optimised fuel cells as they can result in reduced efficiency and lifetime. Current PEFCs are in a state where they are commercially viable but have a very limited temperature operation region (<80°C). This meta-study analysis presents research around expanding the operational temperatures of PEFCs through a parametric analysis of active cell area, phosphonic acid content, and organic/inorganic fillers. This analysis finds an increase in proton conductivity for PEFCs at higher temperature by using phosphonic acid functionalised membranes with maximised degree of phosphonation (up to 1.5 DP). It was also found that using ionic liquid functionalised carbon materials as fillers was an effective strategy to enhance the proton conductivity of PEFCs in a higher temperature environment while also providing increased thermal stability of the membrane. Additionally, higher thermal efficiency and power density may be achieved by increasing temperature and humidity to maximise proton conductivity towards theoretical maxima dictated by the active cell area, which was found to peak at 36 cm2.