Best Practices for Investigating Anion Exchange Membrane Suitability for Alkaline Electrochemical Devices: Case Study Using Quaternary Ammonium Poly(2,6-dimethyl 1,4-phenylene)oxide Anion Exchange Membranes

Abstract

Alkaline fuel cells containing anion exchange membrane electrolytes (i.e., solid-state alkaline fuel cells - SAFCs) promise to provide high power densities without platinum group metal catalysts. In the past decade, SAFC performance has improved substantially due to improvements in electrode binders that facilitate good membrane-electrode contact and ionic conductivity in the electrode layer. However, the alkaline (in)stability of AEMs is a long-standing challenge that currently precludes commercialization of this technology. To date, there have not been any satisfactory strategies or approaches to adequately assess an AEM's suitability for SAFC applications. Here, we report an all-encompassing “best practices” approach to evaluate a leading AEM candidate (poly(2,6-dimethyl 1,4-phenylene) oxide (PPO) with quaternary ammonium groups) for SAFCs. Additionally, this work reports an excellent peak power density of 294 mW cm−2 when the fuel cell was operated with hydrogen-oxygen. This high fuel cell performance was attained by painting the electrodes directly onto the membrane to minimize membrane-electrode contact resistance losses.