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

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.