Alkaline Exchange Fuel Cell Membrane Ionomers Containing Spirocyclic Repeat Units in an All Carbon Backbone for Enhanced Durability

Abstract

Alkaline exchange membrane fuel cells (AEMFC)s continue to gain interest as a potential lower cost alternative to the commercially available proton exchange membrane fuel cells (PEMFC)s. Recently there have been significant advances in the performance of AEMFC systems achieving greater than 1 1-2, albeit with PGM catalysts. However, the incorporation of non PGM catalyst materials will significantly reduce costs. One of the more significant challenges to the commercialization of AEMFCs is demonstrating long term durability under operating conditions and over startup/shutdown cycles. Improving the durability of the ionomers employed in alkaline exchange membranes and catalyst ink formulations will enhance the long term durability of AEMFCs. Enhancing the durability of alkaline ionomers has focused on the installation of more stable cationic head groups3. Previous research has demonstrated the incorporation of spirocyclic repeat units into multiblock copolymers of polysulfone4. The research presented demonstrates the incorporation of the spirocyclic polymer poly(diallylpiperidinium hydroxide) into an all carbon backbone of hydrophobic/hydrophilic block copolymers. The synthesis, characterization and performance is pesented. Omasta, T. J.; Peng, X.; Miller, H. A.; Vizza, F.; Wang, L.; Varcoe, J. R.; Dekel, D. R.; Mustain, W. E., Beyond 1.0 W cm-2 performance without platinum: the beginning of a new era in anion exchange membrane fuel cells. J. Electrochem. Soc. 2018, 165 (15), J3039-J3044.Omasta, T. J.; Zhang, Y.; Park, A. M.; Peng, X.; Pivovar, B.; Varcoe, J. R.; Mustain, W. E., Strategies for Reducing the PGM Loading in High Power AEMFC Anodes. J. Electrochem. Soc. 2018, 165 (9), F710-F717.Marino, M. G.; Kreuer, K. D., Alkaline Stability of Quaternary Ammonium Cations for Alkaline Fuel Cell Membranes and Ionic Liquids. ChemSusChem 2015, 8 (3), 513-523.Strasser, D. J.; Graziano, B. J.; Knauss, D. M., Base stable poly(diallylpiperidinium hydroxide) multiblock copolymers for anion exchange membranes. J. Mater. Chem. A 2017, 5 (20), 9627-9640.