Impact of Catalyst Ink Dispersing Methodology on Fuel Cell Performance Using In-situ X-ray Scattering

Min Wang, Sadia Kabir, Kenneth Neyerlin, Michael Ulsh, Scott Mauger, Jae Park, Nancy Kariuki, Haifeng Lv, Vojislav Stamenkovic, Deborah Myers

Research output: Contribution to journalArticlepeer-review

110 Scopus Citations

Abstract

This work presents a study of the effects of ultrasonic dispersing methodology and time on catalyst agglomerate size in polymer electrolyte membrane fuel cell (PEMFC) catalyst ink dispersions. Cathode catalyst inks were prepared and characterized to elucidate the influences of ultrasonic dispersing method and time on catalyst ink particle size and CCL electrochemical properties. In-situ ultra-small-, small-, and wide-angle X-ray scattering (USAXS-SAXS-WAXS) analyses were used to study the impact of ultrasonication time and methodology on changes in the agglomerate, aggregate, and particle size and distribution during the dispersing process. Ex-situ transmission electron microscopy was also used to investigate the particle size of these inks. Fuel cell membrane electrode assemblies (MEAs) were prepared and tested to determine the influence of ink properties on CCL electrochemical properties, including the electrochemical active surface area (ECA), mass activity (MA), H2/air polarization curves, and oxygen mass-transport resistances. It was found that a combination of brief tip sonication followed by bath sonication was most effective at breaking up agglomerates, leading to maximum catalyst activity and MEA performance. Extended tip sonication was found to be too aggressive and resulted in detachment of the platinum nanoparticles from the carbon black support, which decreased electrochemical surface area and MEA performance. Quantification of oxygen mass transport resistance showed that electrodes with large catalyst agglomerates due to insufficient sonication had a higher non-Fickian (pressure independent) than properly dispersed catalyst. Through correlation of the performance with catalyst particle size, the desired CCL structure was proposed, which will provide insight into dispersion strategies for lab-scale spray coating and other processing techniques as well as for large-scale manufacturing.

Original languageAmerican English
Pages (from-to)6417-6427
Number of pages11
JournalACS Applied Energy Materials
Volume2
Issue number9
DOIs
StatePublished - 23 Sep 2019

Bibliographical note

Publisher Copyright:
© 2019 American Chemical Society.

NREL Publication Number

  • NREL/JA-5900-74266

Keywords

  • catalyst ink
  • dispersing
  • in-situ X-ray scattering
  • particle size
  • proton-exchange membrane fuel cells
  • USAXS

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