Fabrication of High Power, Low-Pt Catalyst Coated Membranes

Abstract

Fabrication of High Power, Low-Pt Catalyst Coated Membranes Yannick Garsany1 and Karen Swider-Lyons2 1 EXCET INC, Springfield, VA 2 U.S Naval Research Laboratory, Washington, DC In the endeavor to create fuel cells capable of generating high power at low platinum loadings, it is crucial that educational and research laboratories have practical, cost-effective ways to make custom membrane electrode assemblies (MEAs). This talk will describe a reliable and reproducible laboratory-scale fabrication protocol based on ultrasonic spray deposition of standard Pt/carbon electrocatalyst directly onto a perfluorosulfonic acid membrane to produce 10 cm2 catalyst coated membranes (CCMs). The CCMs are then transformed into MEAs by compressing them between commercial gas diffusion media (GDM). We present the scientific rationale and electrochemical and microscopy data to reveal how post-deposition processing of the CCM/MEA and assembly conditions affect the performance of single cell fuel cells. Improper post-deposition processing leads to damage of the pore structure of the catalyst layer and/or GDM, diminishing the overall fuel cell performance. Fuel cells that are not assembled properly, either due to under- or over-compression, have high ohmic resistance or damage to the GDM pore structure, both of which negatively affect the PEMFC performance, despite no structural changes in the CCM. Equipped with the understanding of how to reproducibly fabricate standard Pt/Carbon CCMs/MEAs, we have adapted these protocols and tools to produce CCMs/MEAs with a PtCo/C electrocatalyst, short side-chain ionomers, and woven GDM that produce the high power and low Pt loadings desired for advanced fuel cells (Figure 1).