Alkali-stable partially fluorinated poly(arylene ether) anion exchange membranes with a claw-type head for fuel cells

Abstract

To enhance the conductivity and alkaline stability of anion exchange membranes (AEMs), partially fluorinated poly(arylene ether) AEMs with functionalized claw-type side chains are prepared. It is found that the integration of a claw-type head into the side chain and a fluorinated moiety into the backbone is favorable for forming a well-defined hydrophilic/hydrophobic phase-separated structure, as confirmed by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). A highest hydroxide conductivity of 98.19 mS cm⁻¹ is achieved for FPAE-3B-3.0-PD with an ion exchange capacity (IEC) of 1.16 meq. g⁻¹. Besides, the as-prepared AEMs exhibit good dimensional stability, robust mechanical properties and high thermal stability. The FPAE-3B-3.0-PD membrane still maintains about 94% and 93% of its initial IEC and conductivity after being immersed in a 1 M aqueous KOH solution at 80 °C for 600 h. The change in the chemical structure of the AEM before and after the alkaline stability test is negligible, as noted by ¹H NMR. Furthermore, the single cell using FPAE-3B-3.0-PD has a highest power density of 156 mW cm⁻² at a current density of 350 mA cm⁻² at 80 °C.