Development of Thermally Processible Anion Exchange Membranes with Improved Interfacial Contact, Performance and Durability for Use in Alkaline Exchange Membrane Water Electrolysis

Hydrogen is at the forefront of clean energy use and storage in the goal to drastically reduce anthropogenic carbon dioxide emissions and combat global climate change. However, hydrogen production to-date is accomplished via steam methane reforming, which produces 5.5 tons of CO 2 for every ton of H 2 produced. The solution is the production of clean hydrogen through water electrolysis. Of the several possible commercial water electrolysis technologies available, proton exchange membrane water electrolysis (PEMWE) and alkaline exchange membrane water electrolysis (AEMWE) are the most promising. PEMWE currently offers the most benefits which include operation at lower temperatures, differential pressure, and high current density (≥3 A/cm -2) . PEMWEs however, have several significant disadvantages for large scale use which include hydrogen crossover, leading to loss of efficiency, the necessity of scarce and expensive platinum group metals (PGM) for catalysts, as well as the need to use expensive perfluorinated membranes. The use of perfluorinated membranes is also included in the growing environmental concern of forever chemicals. All these factors make AWMWEs an attractive alternative. AEMs should be thermally processible to enable hot-press membrane electrode assembly (MEA) fabrication, which would improve interfacial contact, decrease or eliminate the need for supporting electrolyte, and increase cell efficiency and durability. Ultimately, thermally processible AEMs would greatly increase MEA manufacturability leading to AEMWE commercialization. Giner Labs is developing thermally processible, hydrocarbon based AEMs and ionomers which can be fabricated into thin films and used in thermal electrode decal transfer. We report on the synthesis, through Ziegler-Natta copolymerization, of stereospecific copolymers of polypropylene with halogen substituted pendants to produce high performing anion exchange membranes. Giner Labs successfully developed a series of materials that could be thermally fabricated into thin films followed by functionalization with trimethylammonium cations. The initial membranes demonstrated good hydroxide conductivity and single cell performance for the associated MEAs. Our ultimate goal is to demonstrate the manufacturability of MEAs in large scale from our membranes using hot-pressing and decal transfer of electrodes and demonstrate superior cell performance and durability compared to other commercial membranes available in the market today.