The Ionomer–Carbon Interaction: A Key Parameter in the Power Performance of Anion Exchange Membrane Fuel Cell

Abstract

Compared to the remarkable advances in anion exchange ionomers (AEIs), the catalyst layer (CL) of the anion exchange membrane fuel cell (AEMFC) has not been sufficiently engineered. Our molecular simulations reveal that the AEIs widely used in this field have weak interaction with the carbon support, presenting the possibility of significant ionomer aggregation in CL. To demonstrate the issue of ionomer–carbon interaction, we investigated CL morphology for various AEIs including polycarbazole-based ionomer (QPC-TMA), FAA-3, PiperION, Sustainion, and compared them with Nafion ionomer that has strong interaction with carbon. In contrast to the uniform Nafion distribution and open-pore structure of Nafion-based CLs, these AEIs are locally aggregated in CL and clog the interstitial pores between the catalyst particles. Furthermore, the comparison of two AEIs with distinct ionomer–carbon interaction energies exhibits that the ionomer with a lower ionomer–carbon interaction energy leads to larger kinetic and mass transport overvoltages. This study provides a fresh perspective that ionomer–carbon support interaction has a significant effect on the structure and performance of the CL.

Key findings

• ▸AEIs have weak interaction with carbon support, causing ionomer aggregation in CL.
• ▸Nafion ionomer has strong interaction with carbon, resulting in uniform distribution and open-pore structure in CL.
• ▸Ionomer-carbon interaction energy affects kinetic and mass transport overvoltages in AEMFC.

Keywords

Identifiers

DOI

10.1149/1945-7111/ad0a7e

Journal

Journal of The Electrochemical Society

Year

2023