Effect of Ionomer Solvents for Pore Size Control of Imidazolium-Base Ionomers in Aemfc

Abstract

Anion exchange membrane fuel cells (AEMFCs) have a low activation overvoltage due to the fast oxygen reduction reaction (ORR) response to alkaline conditions compared to the acidic condition of proton exchange membrane fuel cells (PEMFCs). The reasons for low activation overvoltage in AEMFCs are diversely studied. Recently, the binder ionomer in the catalyst layer of polymer electrolyte membrane fuel cells has attracted increasing attention because of its critical role in power performance and the durability of the catalyst layer. Ionomer covers the catalyst surfaces, providing anion transport between the catalyst surfaces and the membrane, as well as mechanical connection. Several requirements as a binder are to have high ion conductivity, gas permeability, and electron conductivity. For durability of membrane electrode assembly (MEA), the binder must have high oxidative stability, and mechanical integrity, less excessive swelling is detrimental. Unususally as AEMs and binder materials, functional groups such as quaternary ammonium (QAs), phosphonium, guanidinium, tertiary sulfonium, pyridinium, and imidazolium ionic liquid (IILs) are used as cation groups. Among them, the QAs has higher chemical and thermal stability than phosphonium, guanidinium and tertiary sulfonium ions. However, the QAs groups tend to be degraded by OH- counterion in high pH environments. In this study, we prepared a binder using IILs instead of the commonly used QAs. Imidazolium-based binders are uncomplicated to design the polymer and easy to synthesize. Furthermore, effect of different alcohols in ionomer binder solution on the shale and pore size of catalyst layer is presented here. The aim of this study is to find out the effect of alcohols in binder ionomers for alkaline fuel cell performance. Figure 1