Fluorinated Poly(thiophene-based aryl piperidinium) Anion-Exchange Membranes Containing Dual Cation–Dipole Interactions for Alkaline Fuel Cells

Abstract

At present, in order to expand and extend the application scope of anion-exchange membrane fuel cells (AEMFCs) in response to the global development of green energy, the design and development of anion exchange membranes (AEMs) that combine high electrochemical performance and long life is a matter of great urgency. In this paper, a series of QPTPTMT-x AEMs with different contents of 2,2,2-trifluoro-1-(5-methoxythiophen-2-yl)ethan-1-one (TMTE) were prepared by first synthesizing TMTE monomers and then introducing them into the polyaryl piperidine skeleton via an ultrastrong acid-catalyzed reaction. With the introduction of TMTE monomers, the F atom provides strong hydrophobicity, while the S heteroatom is present to facilitate intermolecular interactions. On the other hand, –CF3 and O atoms interact together with cations to produce dual cation–dipole interactions. The comprehensive performance of QPTPTMT-x AEMs produces great improvement. Particularly, QPTPTMT-20 AEM with the lowest ion-exchange capacity and swelling ratio achieved the best ionic conductivity of 180.1 mS cm–1 at 80 °C while possessing a tensile strength of 72 MPa. After immersion in 3 M NaOH for 1080 h, the conductivity retention of the AEMs was still 94.4%. Last, the membranes were prepared into membrane electrode assemblies for single-cell performance testing. The QPTPTMT-20 AEM demonstrated a peak power density of 416 mW cm–2 at 80 °C.