Novel Strategy for Engineering Ultra-Thin Proton Exchange Membranes for Advanced PEM Fuel Cells

Abstract

The energy needs of the modern world currently relies heavily on fossil fuels and energy conversion technologies that emit greenhouse gases (GHGs). These GHGs have been shown to have a detrimental impact on global climate. Climate change has created a vital shift in the way society thinks about energy conversion and storage. Today we are seeing huge increase in the demand for utilization of renewable energy sources (solar, wind, and etc.) as well as in their integration with zero-carbon emission energy conversion and storage devices such as fuel cells, water electrolyzers, and batteries. The renewable energy sources are intermittent by nature since the wind does not always blow and the sun does not always shine. This creates a need for a way to store excess green energy that would otherwise be wasted when the demand does not meet the production. Development of advanced Proton Exchange Membrane (PEM) water electrolyzers and fuel cells that can be integrated with renewable energy sources to convert the excess electricity to hydrogen, is the most efficient approach for sustainable energy storage and utilization. Development of such sustainable energy systems is of primary importance for implementation and widespread application of the green energy technologies in our everyday life and elimination of the GHG emissions. Low temperature Polymer Electrolyte Membrane Fuel Cells (PEMFC) are the most promising type of fuel cells for application in the transportation sector. Currently, the commercialization of these devices is hindered by their high cost and limited durability. Further research is needed to increase their efficiency, power output, catalyst utilization, and durability. Fabrication of thinner proton conductive membranes, is one of the strategies that are of particular research interest. Successful development of thinner PFSA membranes will result in reduction of the ohmic resistance of the MEAs, cost reduction, and will improve their performance. Fabrication of thinner PEM membrane is a challenging task that requires innovative engineering approaches that will allow to fabricate ultra-thin, pinhole free membranes with the desired mechanical stability and hydrogen crossover suppression properties. This work aims on development of novel approaches for engineering ultra-thin PEM membranes with thicknesses below 10µm, and to perform a systematic study of the membrane thickness impact on the MEAs cost, activity, and durability performance. In addition, the effect of various reinforcement materials on the membrane properties have been studied, and their optimal concentrations and position in the volume of the membrane has been investigated. All PEM membranes of interest have been fabricated with a state-of-the-art ultrasonic spray deposition method, designed, and developed at UConn. This methodology allows for precise control of the thickness and composition of the thin membranes, as well as of the thickness, composition, and precious metal loading in the catalysts layers. The newly designed MEAs have been tested at real fuel cell operating conditions, and the results will be presented and discussed in detail at the 243rd ECS meeting in Boston, MA.