DESC0025020

Currently, the high-performance perfluorinated SOTA membranes and ionomers used in proton exchange membrane water electrolyzer stacks are derived from perfluoroalkyl substances (PFAS) which are known to have significant environmental persistence and are being studied for their negative impacts on human health. The implications of the heightened concerns related PFAS are that in the near future it is expected that significant regulations or bans will be imposed. Therefore, it is imperative to the hydrogen economy and clean energy that alternative hydrocarbon-based membranes/ionomers be developed. The proposed research will address this situation through the development of a polyethylene-based, drop-in replacement analogue of the current SOTA perfluorinated membranes. The polyethylene-based materials will be fully saturated e.g., no double bonds or aromatic structures, thereby eliminating known phenyl absorption onto platinum catalyst degradation, and will maintain current thermal processing characteristics observed in perfluorinated membranes. It is also expected that the proposed membranes and ionomers will require minimal changes to the well-developed manufacturing practices for fabricating membranes, electrodes, and membrane/electrode assemblies utilized in PEMWE systems. For this project we will be utilizing Ziegler-Natta polymerization of ethylene with functionalized comonomers. We expect that higher lower equivalent wight materials will be necessary to obtain the necessary performance, and with that water management will be key. Our strategy to de-risk the water management is to utilize woven PEEK support materials. Ultimately, the materials developed will be less expensive, commercially scalable, and further DOEĺs target of $1 per kg for hydrogen. The PFAS-free PEMs and ionomers developed in this Phase I project will have broad applicability. Such materials will find use a range of electrochemical devices that currently utilize perfluorinated polymers such as fuel cells, electrolyzers, sensors, desalination, and electrochemical direct air capture of CO2. Furthermore, the reduced cost will enable quicker and more expansive adoption of hydrogen technology as a fuel and energy source.