0

Full Content is available to subscribers

Subscribe/Learn More  >

The Effect of Electric Double Layers on Ionic Conductivity in the Agglomerates of PEM Fuel Cell Anodes

[+] Author Affiliations
Iryna Zenyuk, Shawn Litster

Carnegie Mellon University, Pittsburgh, PA

Paper No. FuelCell2010-33299, pp. 761-769; 9 pages
doi:10.1115/FuelCell2010-33299
From:
  • ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology
  • ASME 2010 8th International Fuel Cell Science, Engineering and Technology Conference: Volume 1
  • Brooklyn, New York, USA, June 14–16, 2010
  • Conference Sponsors: Advanced Energy Systems Division
  • ISBN: 978-0-7918-4404-5 | eISBN: 978-0-7918-3875-4
  • Copyright © 2010 by ASME

abstract

We present a theoretical analysis of ionic transport inside the catalyst particle agglomerates that form the electrodes of proton exchange membrane (PEM) fuel cells. The electrodes continue to be the subject of intense research and development because they are still the largest cost and source of performance degradation in PEM fuel cells. The advancement of electrodes requires proper understanding of the electrode structure and the relevant transport processes. However, the details of the electrode microstructure and the micro-scale and nano-scale transport mechanisms are still not well understood. A common hypothesis, supported by recent coarse-grained molecular dynamics simulations, is that the primary pores (the pores inside the agglomerates) are void space and not filled with Nafion electrolyte. Instead, it has been postulated that the primary pores are saturated with liquid water during operation. Here, we report on the effect of the electric double layers (EDLs), which form at the interface between the water and the carbon catalyst supports, on the ionic transport within the agglomerates. The multi-scale model addresses phenomena at two length scales: (1) the nano-scale EDL thickness and (2) the microscale agglomerate radius. We model the EDL using the Gouy-Chapman-Stern model, which provides a pore average conductivity for the spherical conduction-reaction model of the agglomerate. We use a spherical agglomerate model to calculate an effectiveness factor for the electrochemical reactions. Here we present the application of the model to the anode, where the low activation overpotential allows linearizations and convenient analytical solutions. A key finding of this work is the important role the EDLs have in establishing the effectiveness of the platinum catalyst utilization. In addition, we resolve the dependence of the agglomerate effectiveness factor on the activation overpotential and agglomerate radius. We observe a significant nonmonotonic dependence of the catalyst effectiveness factor on the overpotential and dramatic improvement in effectiveness of catalyst utilization with smaller agglomerates.

Copyright © 2010 by ASME

Figures

Tables

Interactive Graphics

Video

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In