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Title: Electrode Edge Cobalt Cation Migration in an Operating Fuel Cell: An In Situ Micro-X-ray Fluorescence Study

PtCo-alloy cathode electrocatalysts release Co cations under operation, and the presence of these cations in the membrane electrode assembly (MEA) can result in large performance losses. It is unlikely that these cations are static, but change positions depending on operating conditions. A thorough accounting of these Co cation positions and concentrations has been impossible to obtain owing to the inability to monitor these processes in operando. Indeed, the environment (water and ion content, potential, and temperature) within a fuel cell varies widely from inlet to outlet, from anode to cathode, and from active to inactive area. Here, synchrotron micro-X-ray fluorescence (μ-XRF) was leveraged to directly monitor Co 2+ transport in an operating H 2/air MEA for the first time. A Nafion membrane was exchanged to a known Co cation capacity, and standard Pt/C electrocatalysts were utilized for both electrodes. Co Kα 1 XRF maps revealed through-plane transient Co transport responses driven by cell potential and current density. Because of the cell design and imaging geometry, the distributions were strongly impacted by the MEA edge configuration. These findings will drive future imaging cell designs to allow for quantitative mapping of cation through-plane distributions during operation.
Authors:
ORCiD logo [1] ;  [1] ; ORCiD logo [2] ;  [1] ;  [1] ; ORCiD logo [1] ;  [1] ; ORCiD logo [2] ; ORCiD logo [2]
  1. General Motors (GM), Pontiac, MI (United States). Global Fuel Cell Business
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-18-20372
Journal ID: ISSN 0013-4651
Grant/Contract Number:
AC52-06NA25396; AC02-06CH11357; EE0007271
Type:
Published Article
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 165; Journal Issue: 6; 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 Office (EE-3F); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; Energy Sciences; Fuel cell, XRF, Durability, Co, cation migration
OSTI Identifier:
1426004
Alternate Identifier(s):
OSTI ID: 1441341

Cai, Yun, Ziegelbauer, Joseph M., Baker, Andrew M., Gu, Wenbin, Kukreja, Ratandeep S., Kongkanand, Anusorn, Mathias, Mark F., Mukundan, Rangachary, and Borup, Rod L.. Electrode Edge Cobalt Cation Migration in an Operating Fuel Cell: An In Situ Micro-X-ray Fluorescence Study. United States: N. p., Web. doi:10.1149/2.0201806jes.
Cai, Yun, Ziegelbauer, Joseph M., Baker, Andrew M., Gu, Wenbin, Kukreja, Ratandeep S., Kongkanand, Anusorn, Mathias, Mark F., Mukundan, Rangachary, & Borup, Rod L.. Electrode Edge Cobalt Cation Migration in an Operating Fuel Cell: An In Situ Micro-X-ray Fluorescence Study. United States. doi:10.1149/2.0201806jes.
Cai, Yun, Ziegelbauer, Joseph M., Baker, Andrew M., Gu, Wenbin, Kukreja, Ratandeep S., Kongkanand, Anusorn, Mathias, Mark F., Mukundan, Rangachary, and Borup, Rod L.. 2018. "Electrode Edge Cobalt Cation Migration in an Operating Fuel Cell: An In Situ Micro-X-ray Fluorescence Study". United States. doi:10.1149/2.0201806jes.
@article{osti_1426004,
title = {Electrode Edge Cobalt Cation Migration in an Operating Fuel Cell: An In Situ Micro-X-ray Fluorescence Study},
author = {Cai, Yun and Ziegelbauer, Joseph M. and Baker, Andrew M. and Gu, Wenbin and Kukreja, Ratandeep S. and Kongkanand, Anusorn and Mathias, Mark F. and Mukundan, Rangachary and Borup, Rod L.},
abstractNote = {PtCo-alloy cathode electrocatalysts release Co cations under operation, and the presence of these cations in the membrane electrode assembly (MEA) can result in large performance losses. It is unlikely that these cations are static, but change positions depending on operating conditions. A thorough accounting of these Co cation positions and concentrations has been impossible to obtain owing to the inability to monitor these processes in operando. Indeed, the environment (water and ion content, potential, and temperature) within a fuel cell varies widely from inlet to outlet, from anode to cathode, and from active to inactive area. Here, synchrotron micro-X-ray fluorescence (μ-XRF) was leveraged to directly monitor Co2+ transport in an operating H2/air MEA for the first time. A Nafion membrane was exchanged to a known Co cation capacity, and standard Pt/C electrocatalysts were utilized for both electrodes. Co Kα1 XRF maps revealed through-plane transient Co transport responses driven by cell potential and current density. Because of the cell design and imaging geometry, the distributions were strongly impacted by the MEA edge configuration. These findings will drive future imaging cell designs to allow for quantitative mapping of cation through-plane distributions during operation.},
doi = {10.1149/2.0201806jes},
journal = {Journal of the Electrochemical Society},
number = 6,
volume = 165,
place = {United States},
year = {2018},
month = {3}
}