Disentangling water, ion and polymer dynamics in an anion exchange membrane

Abstract Fuel cells that generate electrical power by the direct electrochemical conversion of fuel to electricity are expected to become important sustainable energy sources for transportation and stationary applications. Polymer electrolyte membrane fuel cell (PEMFC) systems operating with oxygen and hydrogen or bio-derived fuels require an ion exchange membrane to transport H+ or OH- ions between the anode and cathode. Proton conduction in Nafion membranes is well studied. However these PEMFC systems rely on noble metal electrocatalysts due to the corrosive nature of the acidic electrolyte. An alkaline electrolyte allows non-noble catalysts to be used at the cathode, leading to reduced cost and enhanced sustainability. Understanding OH- transport and how it influences water management and polymer dynamics in anion exchange membranes (AEMs) is a critical design challenge and design parameter. Here, neutron scattering is used to disentangle the water, polymer relaxation and OH- diffusion dynamics in a commercial AEM system