UNS: Microstructural determinants of ion transport in ion exchange fuel cell membranes

Stanford University, Stanford CA

Investigators

Abstract

1511373 - Frank, Curtis; Spakowitz, Andrew; Toney, Michael Ion exchange membrane (IEM) fuel cells constitute an enticing alternative energy source whose operation generates water rather than more harmful carbon-based emissions. Efficient operation of a fuel cell hinges on developing a polymer membrane that permits ions to move quickly between the electrodes in the fuel cell. This is typically accomplished using a copolymer with hydrophobic and hydrophilic monomers that phase separate at nanometer length scales. The resulting hydrophobic matrix confers mechanical stability to the membrane, while the hydrophilic domains provide pathways for ions to move between electrodes. Ion transport through the polymer membrane is dictated by the organization of the phase-segregated domains at length scales ranging from nanometers to microns. The rational design of an IEM requires a clear connection between the chemical arrangement of monomers within the copolymers and the resulting molecular-level organization of the ion-transport domains. Such materials are crucial to our future energy utilization, and establishing the structure-function relationship in polymer membranes is crucial to improving fuel-cell performance. This research program combines theoretical modeling, synthesis, and characterization of ion exchange membranes (IEM). The PIs will use a combination of analytical theory and computational modeling to predict the morphology of polymer membranes composed of poly(ethylene oxide)-polyimide (PEO-PI) copolymer materials synthesized in the collaboration, and test and validate the model to provide theoretical guidance for optimizing the performance of IEM materials. The theoretical model, which leverages and extends the existing approaches to modeling random copolymers, will be capable of predicting microphase segregation in other polymer membrane systems. Therefore, establishing this capability of theoretical investigation and experimental testing enables the prediction of microphase organization and material performance in a broad range of polymer membrane materials for fuel cell and other applications. The outreach efforts include the establishment of the LABScI program, which develops and implements teaching modules for the education of high school students that are being treated for childhood cancer. This program has made a major impact on the education of high school students at the Hospital School at the Lucile Packard Children's Hospital. Future outreach efforts aim to further expand our program nationwide as a general laboratory science curriculum for hospital-school education. The PIs will continue to pair with high-school teachers and students during the summers to receive feedback on the ease of implementation, consistency with high-school science standards, and student understanding of the teaching modules.