Anion Conducting Ionomers for Electrochemical Devices

The design of new anion exchange ionomers for use in electrochemical devices is a critical step in improvement of anionic fuel cells and electrolyzers. Although these materials can be made from the same precursors as anion exchange membranes (AEM), they have very different property requirements. Since ionomers are used within the electrode layers, they do not act as a separator for fuel and air but rather help transport reactants and products to and from the electrocatalyst surface. In this study, a series of anionic ionomers was synthesized and tested in fuel cell and electrolyzer configurations. These ionomers are based on fluorinated poly(arylene ether) homopolymers and block copolymers with alkyl tethers that have been modified to be used as anion conductors. In situ testing of these materials shows that lower molecular weight materials outperform their higher molecular weight counterparts. Additionally, the use of a block copolymer with the introduction of a hydrophobic spacer further increases device performance.