High Temperature PEM Fuel Cells

Project start date Aug. 15, 2024.

To sustain autonomous ground vehicle capabilities in the field in the long run, they will need to be powered by a variety of fuels. Hydrogen fuel cells is one of those options. Current PEMs (proton exchange membrane) use Nafion®,. Its proton transport mechanism follows the Grotthuss mechanism where water molecules carry protons. This requires hydration and strong acid to be effective, which limits the durability of the membrane as well as the temperature that it can be used. Additionally, all have to be operated with high purity hydrogen due to the low operating temperature.

In this project, we will develop and optimize a fluorinated, branched, polymer that will also use imidazole as the proton transporting groups for fuel cell membranes that are waterresistant and mechanically and thermally stable at 150-180 °C, but will also contain enough free volume around the imidazole to optimize proton transport. This should improve the efficiency of proton transport at high temperature. Optimization will occur in an iterative process using results from a molecular dynamics (MD) simulation to synthesize and test selected structures. We will also develop membranes from this material.

The specific objectives of this proposal are:

1. Develop a structure model using MD and coarse-grain dynamics simulations to study proton transfer.
2. Synthesize optimized fluorinated, branched polymer with imidazole.
3. Optimize membrane preparation.
4. Obtain basic electrical membrane parameters.
5. Prepare and test membrane electrode assembly.

The basic syntheses (18-23) have been developed earlier (18-23) as well as the basic molecular dynamics model (24) has been developed earlier. Our next step involves enhancing the structure through an iterative process that includes computer modeling, synthesis of the most promising options, testing, and refinement of the computer model.

Prior publications:

18. Quast, M.J.; Mueller, A. “Membrane Preparation from Hyperbranched Perfluorinated Polymers”, Journal of Polymer Science, Part A: Polymer Chemistry 2019, 57, 961-972.
19. Quast, M.J.; Argall, A.; Hager, C.; Mueller, A. “Physical, Thermal, and Mechanical Properties of Highly Branched Perfluorinated AB + AB2 Copolymer Systems”, Journal of Polymer Science, Part A: Polymer Chemistry 2015, 53, 1880–1894.
20. Quast, M.J.; Mueller, A. “Hyperbranched Polyfluorinated Benzyl Ether Polymers: Mechanism, Kinetics, and Optimization”, Journal of Polymer Science, Part A: Polymer Chemistry 2014, 52, 985–994.
21. Gan, D.; Mueller, A.; Wooley, K. L. “Amphiphilic and Hydrophobic Surface Patterns Generated from Hyperbranched Fluoropolymer(HBFP)–Linear Polymer Networks: Minimallyadhesive coatings via crosslinking of hyperbranched fluoropolymers”, J. Polym. Sci., Part A: Polym. Chem. 2003, 41(22), 3531-40.
22. Gooden, J.; Gross, M. L.; Mueller, A.; Stefanescu, A.; Wooley, K. L. “Cyclization in Hyperbranched Polymer Syntheses: Characterization by MALDI-TOF Mass Spectrometry”, J. Am. Chem. Soc. 1998, 120, 10180-10186.
23. Mueller, A.; Kowalewski, T.; Wooley, K. L. “Synthesis and Characterization of Hyperbranched Polyfluorinated Polymers”, Macromolecules 1998, 31, 776-786.\
24. Rakesh, L.; Mueller, A.; Chhetri, P. “Development of a Hyperbranched Fuel Cell Membrane Material for Improved Proton Conductivity”, Fluid Dynamics and Material Processing 2010,

3.A117