High-Throughput Anion Exchange Membrane Characterization at NREL

Abstract

Alkaline fuel cells (AFCs) are of high interest because they utilize lower cost catalyst and separator materials relative to polymer electrolyte membrane fuel cells. AFCs require anion exchange membranes (AEMs) that have high alkaline chemical stability, high hydroxide ion conductivity, and adequate thermal/mechanical properties. While numerous AEMs have been developed as solid-state electrolytes for AFCs, there is still disagreement in literature on standard membrane testing procedures and optimal membrane chemistry to ensure peak long-term AFC performance. Currently, NREL is developing tools and protocols to allow for high throughput, parallel characterization of AEM materials. More specifically, NREL has received membranes from more than 10 partners and has tested more than 50 membranes using these approaches. This is allowing us to gain valuable insight into different backbone and cation strategies. In many cases these ex-situ results can be compared to fuel cell performance and durability. Technical investigations include conductivity, ion exchange capacity, mechanical performance, chemical stability, thermal properties, water uptake, swelling, and fuel cell performance. Structure-property relationships that are determined to improve membrane performance and durability will be discussed, lending insight into optimal backbone and cation strategies to employ in development of AEMs. Figure 1