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Title: Modeling Electrochemical Performance of the Hierarchical Morphology of Precious Group Metal-free Cathode for Polymer Electrolyte Fuel Cell

Here, this paper presents a two-dimensional (2D) computational model of a polymer electrolyte fuel cell (PEFC) with a platinum group metal-free (PGM-free) catalyst cathode that can significantly reduce PEFC costs by eliminating the need for expensive platinum catalysts. Due to their comparatively low volumetric activity, PGM-free cathodes are an order of magnitude thicker than their Pt-based counterpart. The resulting need for greater electrode thickness to achieve sufficient power density requires careful attention to the transport losses across the thicker cathodes. The presented model is used to correlate the composition and morphology of the cathode to PEFC performance. The model is a complete cell, continuum model that includes an advanced agglomerate model for a microstructurally consistent representation of the cathode. A unique feature of the approach is the integration of morphology and transport parameter statistics extracted from nano-scale resolution X-ray computed tomography (nano-CT) imaging of PGM-free cathodes. The model was validated with experimental results of PGM-free cathodes with varying Nafion loading. Lastly, our key findings are a need for increased cathode hydrophobicity and increased ionomer conductivity through either reduced tortuosity or increased bulk conductivity. We further use the model to evaluate targets for the volumetric activity and active site density formore » future catalysts.« less
Authors:
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [2] ;  [3]
  1. Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Mechanical Engineering; Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Mechanical Engineering
Publication Date:
Report Number(s):
LA-UR-17-24482
Journal ID: ISSN 0013-4651
Grant/Contract Number:
AC52-06NA25396; 1229090
Type:
Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 164; Journal Issue: 9; Journal ID: ISSN 0013-4651
Publisher:
The Electrochemical Society
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE). Fuel Cell Technologies Program (EE-3F); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; Energy Sciences
OSTI Identifier:
1394979

Komini Babu, Siddharth, Chung, Hoon Taek, Zelenay, Piotr, and Litster, Shawn. Modeling Electrochemical Performance of the Hierarchical Morphology of Precious Group Metal-free Cathode for Polymer Electrolyte Fuel Cell. United States: N. p., Web. doi:10.1149/2.0041712jes.
Komini Babu, Siddharth, Chung, Hoon Taek, Zelenay, Piotr, & Litster, Shawn. Modeling Electrochemical Performance of the Hierarchical Morphology of Precious Group Metal-free Cathode for Polymer Electrolyte Fuel Cell. United States. doi:10.1149/2.0041712jes.
Komini Babu, Siddharth, Chung, Hoon Taek, Zelenay, Piotr, and Litster, Shawn. 2017. "Modeling Electrochemical Performance of the Hierarchical Morphology of Precious Group Metal-free Cathode for Polymer Electrolyte Fuel Cell". United States. doi:10.1149/2.0041712jes. https://www.osti.gov/servlets/purl/1394979.
@article{osti_1394979,
title = {Modeling Electrochemical Performance of the Hierarchical Morphology of Precious Group Metal-free Cathode for Polymer Electrolyte Fuel Cell},
author = {Komini Babu, Siddharth and Chung, Hoon Taek and Zelenay, Piotr and Litster, Shawn},
abstractNote = {Here, this paper presents a two-dimensional (2D) computational model of a polymer electrolyte fuel cell (PEFC) with a platinum group metal-free (PGM-free) catalyst cathode that can significantly reduce PEFC costs by eliminating the need for expensive platinum catalysts. Due to their comparatively low volumetric activity, PGM-free cathodes are an order of magnitude thicker than their Pt-based counterpart. The resulting need for greater electrode thickness to achieve sufficient power density requires careful attention to the transport losses across the thicker cathodes. The presented model is used to correlate the composition and morphology of the cathode to PEFC performance. The model is a complete cell, continuum model that includes an advanced agglomerate model for a microstructurally consistent representation of the cathode. A unique feature of the approach is the integration of morphology and transport parameter statistics extracted from nano-scale resolution X-ray computed tomography (nano-CT) imaging of PGM-free cathodes. The model was validated with experimental results of PGM-free cathodes with varying Nafion loading. Lastly, our key findings are a need for increased cathode hydrophobicity and increased ionomer conductivity through either reduced tortuosity or increased bulk conductivity. We further use the model to evaluate targets for the volumetric activity and active site density for future catalysts.},
doi = {10.1149/2.0041712jes},
journal = {Journal of the Electrochemical Society},
number = 9,
volume = 164,
place = {United States},
year = {2017},
month = {8}
}