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Title: Resolving Electrode Morphology’s Impact on Platinum Group Metal-Free Cathode Performance Using Nano-CT of 3D Hierarchical Pore and Ionomer Distribution

This paper reports on the characterization of polymer electrolyte fuel cell (PEFC) cathodes featuring a platinum group metal-free (PGM-free) catalyst using nano-scale resolution X-ray computed tomography (nano-CT) and morphological analysis. PGM-free PEFC cathodes have gained significant interest in the past decade since they have the potential to dramatically reduce PEFC costs by eliminating the large platinum (Pt) raw material cost. However, several challenges remain before they are commercially viable. Since these catalysts have lower volumetric activity, the PGM-free cathodes are thicker and are subject to increased gas and proton transport resistances that reduce the performance. To better understand the efficacy of the catalyst and improve electrode performance, a detailed understanding the correlation between electrode fabrication, morphology, and performance is crucial. In this work, the pore/solid structure and the ionomer distribution was resolved in three dimensions (3D) using nano-CT for three PGM-free electrodes of varying Nafion® loading. The associated transport properties were evaluated from pore/particlescale simulations within the nano-CT imaged structure. These characterizations are then used to elucidate the microstructural origins of the dramatic changes in fuel cell performance with varying Nafion® ionomer loading. We show that this is primarily a result of distinct changes in ionomer’s spatial distribution. The significantmore » impact of electrode morphology on performance highlights the importance of PGM-free electrode development in concert with efforts to improve catalyst activity and durability.« less
Authors:
 [1] ;  [2] ;  [2] ;  [1]
  1. Carnegie Mellon Univ., Pittsburgh, PA (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-17-24486
Journal ID: ISSN 1944-8244; TRN: US1702002
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 8; Journal Issue: 48; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; Computed tomography; ionomer imaging; morphological characterization; platinum group metal-free catalyst; transport modeling
OSTI Identifier:
1375885

Komini Babu, Siddharth, Chung, Hoon T., Zelenay, Piotr, and Litster, Shawn. Resolving Electrode Morphology’s Impact on Platinum Group Metal-Free Cathode Performance Using Nano-CT of 3D Hierarchical Pore and Ionomer Distribution. United States: N. p., Web. doi:10.1021/acsami.6b08844.
Komini Babu, Siddharth, Chung, Hoon T., Zelenay, Piotr, & Litster, Shawn. Resolving Electrode Morphology’s Impact on Platinum Group Metal-Free Cathode Performance Using Nano-CT of 3D Hierarchical Pore and Ionomer Distribution. United States. doi:10.1021/acsami.6b08844.
Komini Babu, Siddharth, Chung, Hoon T., Zelenay, Piotr, and Litster, Shawn. 2016. "Resolving Electrode Morphology’s Impact on Platinum Group Metal-Free Cathode Performance Using Nano-CT of 3D Hierarchical Pore and Ionomer Distribution". United States. doi:10.1021/acsami.6b08844. https://www.osti.gov/servlets/purl/1375885.
@article{osti_1375885,
title = {Resolving Electrode Morphology’s Impact on Platinum Group Metal-Free Cathode Performance Using Nano-CT of 3D Hierarchical Pore and Ionomer Distribution},
author = {Komini Babu, Siddharth and Chung, Hoon T. and Zelenay, Piotr and Litster, Shawn},
abstractNote = {This paper reports on the characterization of polymer electrolyte fuel cell (PEFC) cathodes featuring a platinum group metal-free (PGM-free) catalyst using nano-scale resolution X-ray computed tomography (nano-CT) and morphological analysis. PGM-free PEFC cathodes have gained significant interest in the past decade since they have the potential to dramatically reduce PEFC costs by eliminating the large platinum (Pt) raw material cost. However, several challenges remain before they are commercially viable. Since these catalysts have lower volumetric activity, the PGM-free cathodes are thicker and are subject to increased gas and proton transport resistances that reduce the performance. To better understand the efficacy of the catalyst and improve electrode performance, a detailed understanding the correlation between electrode fabrication, morphology, and performance is crucial. In this work, the pore/solid structure and the ionomer distribution was resolved in three dimensions (3D) using nano-CT for three PGM-free electrodes of varying Nafion® loading. The associated transport properties were evaluated from pore/particlescale simulations within the nano-CT imaged structure. These characterizations are then used to elucidate the microstructural origins of the dramatic changes in fuel cell performance with varying Nafion® ionomer loading. We show that this is primarily a result of distinct changes in ionomer’s spatial distribution. The significant impact of electrode morphology on performance highlights the importance of PGM-free electrode development in concert with efforts to improve catalyst activity and durability.},
doi = {10.1021/acsami.6b08844},
journal = {ACS Applied Materials and Interfaces},
number = 48,
volume = 8,
place = {United States},
year = {2016},
month = {11}
}