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Title: Proton Conduction and Oxygen Diffusion in Ultra-Thin Nafion Films in PEM Fuel Cell: How Thin?

Abstract

The success of PEM fuel cells lies in the design of the cathode where C-supported Pt catalyst is covered by a thin layer of ionomer, allowing easy access of oxygen and protons. The high current densities (1-2 A/cm 2) are achieved by the optimization of the thickness of the ionomer between two opposing trends: thinner ionomer allows high oxygen through-plane diffusion, while the in-plane conduction of the protons requires reasonable thickness. Anisotropy is likely to develop in such thin films. The purpose of this work was to investigate the effect of a thinner ionomer layer on the diffusion and conductivity and to establish how thin the ionomer layer can be. Oxygen permeability (DH) and proton conductivity in ultra-thin Nafion films (100-1000nm) were respectively characterized on SiO 2 substrate via limiting current measurement and electrochemical impedance spectroscopy for a range of temperature and relative humidity conditions. The transport behavior of these films is comparable to the electrode membrane layer of PEM fuel cells. Values of oxygen permeability were shown to increase with decreasing film thickness. The oxygen diffusion through the gas boundary layer becomes significant only at ultra-thin film thickness. The proton conductivity decreases with decreasing thickness and was disproportional tomore » bulk Nafion behavior. Post-test SEM imaging shows buckling of the thin layer on the silicon wafer between the Pt sites, partially explaining the opposing trends in diffusivity and conductivity as film thickness decreases. Anisotropy exists as the thickness becomes comparable to the size of the aqueous regions of the Nafion ionomer. Measurements of thinner layers (<100nm) were experimentally limited, yet the trends indicate that the thinness of the ionomer in the cathode is limited by its ability to allow proton conductance.« less

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Univ. of Rochester, NY (United States)
  2. General Motors LLC, Detroit, MI (United States)
Publication Date:
Research Org.:
General Motors LLC, Detroit, MI (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1613261
Grant/Contract Number:  
EE0000470
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 166; Journal Issue: 2; Journal ID: ISSN 0013-4651
Publisher:
IOP Publishing - The Electrochemical Society
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; Electrochemistry; Materials Science

Citation Formats

Chen, Darcy, Kongkanand, Anusorn, and Jorne, Jacob. Proton Conduction and Oxygen Diffusion in Ultra-Thin Nafion Films in PEM Fuel Cell: How Thin?. United States: N. p., 2019. Web. doi:10.1149/2.0101902jes.
Chen, Darcy, Kongkanand, Anusorn, & Jorne, Jacob. Proton Conduction and Oxygen Diffusion in Ultra-Thin Nafion Films in PEM Fuel Cell: How Thin?. United States. doi:10.1149/2.0101902jes.
Chen, Darcy, Kongkanand, Anusorn, and Jorne, Jacob. Sat . "Proton Conduction and Oxygen Diffusion in Ultra-Thin Nafion Films in PEM Fuel Cell: How Thin?". United States. doi:10.1149/2.0101902jes. https://www.osti.gov/servlets/purl/1613261.
@article{osti_1613261,
title = {Proton Conduction and Oxygen Diffusion in Ultra-Thin Nafion Films in PEM Fuel Cell: How Thin?},
author = {Chen, Darcy and Kongkanand, Anusorn and Jorne, Jacob},
abstractNote = {The success of PEM fuel cells lies in the design of the cathode where C-supported Pt catalyst is covered by a thin layer of ionomer, allowing easy access of oxygen and protons. The high current densities (1-2 A/cm2) are achieved by the optimization of the thickness of the ionomer between two opposing trends: thinner ionomer allows high oxygen through-plane diffusion, while the in-plane conduction of the protons requires reasonable thickness. Anisotropy is likely to develop in such thin films. The purpose of this work was to investigate the effect of a thinner ionomer layer on the diffusion and conductivity and to establish how thin the ionomer layer can be. Oxygen permeability (DH) and proton conductivity in ultra-thin Nafion films (100-1000nm) were respectively characterized on SiO2 substrate via limiting current measurement and electrochemical impedance spectroscopy for a range of temperature and relative humidity conditions. The transport behavior of these films is comparable to the electrode membrane layer of PEM fuel cells. Values of oxygen permeability were shown to increase with decreasing film thickness. The oxygen diffusion through the gas boundary layer becomes significant only at ultra-thin film thickness. The proton conductivity decreases with decreasing thickness and was disproportional to bulk Nafion behavior. Post-test SEM imaging shows buckling of the thin layer on the silicon wafer between the Pt sites, partially explaining the opposing trends in diffusivity and conductivity as film thickness decreases. Anisotropy exists as the thickness becomes comparable to the size of the aqueous regions of the Nafion ionomer. Measurements of thinner layers (<100nm) were experimentally limited, yet the trends indicate that the thinness of the ionomer in the cathode is limited by its ability to allow proton conductance.},
doi = {10.1149/2.0101902jes},
journal = {Journal of the Electrochemical Society},
issn = {0013-4651},
number = 2,
volume = 166,
place = {United States},
year = {2019},
month = {1}
}

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Works referenced in this record:

Relationship among Microstructure, Ionomer Property and Proton Transport in Pseudo Catalyst Layers
journal, January 2011

  • Iden, Hiroshi; Sato, Kazuyuki; Ohma, Atsushi
  • Journal of The Electrochemical Society, Vol. 158, Issue 8
  • DOI: 10.1149/1.3598141

Effects of Catalyst Carbon Support on Proton Conduction and Cathode Performance in PEM Fuel Cells
journal, January 2011

  • Liu, Yuxiu; Ji, Chunxin; Gu, Wenbin
  • Journal of The Electrochemical Society, Vol. 158, Issue 6
  • DOI: 10.1149/1.3562945

Analysis of Oxygen-Transport Diffusion Resistance in Proton-Exchange-Membrane Fuel Cells
journal, January 2011

  • Nonoyama, Nobuaki; Okazaki, Shinobu; Weber, Adam Z.
  • Journal of The Electrochemical Society, Vol. 158, Issue 4
  • DOI: 10.1149/1.3546038

Measurement of Oxygen Transport Resistance in PEM Fuel Cells by Limiting Current Methods
journal, January 2009

  • Baker, Daniel R.; Caulk, David A.; Neyerlin, Kenneth C.
  • Journal of The Electrochemical Society, Vol. 156, Issue 9
  • DOI: 10.1149/1.3152226

The Impact of Platinum Loading on Oxygen Transport Resistance
journal, January 2012

  • Greszler, Thomas A.; Caulk, David; Sinha, Puneet
  • Journal of The Electrochemical Society, Vol. 159, Issue 12
  • DOI: 10.1149/2.061212jes

Analysis of Oxygen Dissolution Rate from Gas Phase into Nafion Surface and Development of an Agglomerate Model
conference, January 2010

  • Kudo, Kenji; Suzuki, Takahisa; Morimoto, Yu
  • 218th ECS Meeting, ECS Transactions
  • DOI: 10.1149/1.3484642

Proton Conduction in PEM Fuel Cell Cathodes: Effects of Electrode Thickness and Ionomer Equivalent Weight
journal, January 2010

  • Liu, Yuxiu; Ji, Chunxin; Gu, Wenbin
  • Journal of The Electrochemical Society, Vol. 157, Issue 8
  • DOI: 10.1149/1.3435323

Towards the understanding of proton conduction mechanism in PEMFC catalyst layer: Conductivity of adsorbed Nafion films
journal, August 2011


Thin Shell Model for Proton Conduction in PEM Fuel Cell Cathodes
journal, January 2010

  • Liu, Yuxiu; Jorne, Jacob; Gu, Wenbin
  • Journal of The Electrochemical Society, Vol. 157, Issue 7
  • DOI: 10.1149/1.3429885

Proton Conduction and Oxygen Reduction Kinetics in PEM Fuel Cell Cathodes: Effects of Ionomer-to-Carbon Ratio and Relative Humidity
journal, January 2009

  • Liu, Yuxiu; Murphy, Michael W.; Baker, Daniel R.
  • Journal of The Electrochemical Society, Vol. 156, Issue 8
  • DOI: 10.1149/1.3143965

Analysis of proton exchange membrane fuel cell catalyst layers for reduction of platinum loading at Nissan
journal, December 2011


Depression of proton conductivity in recast Nafion® film measured on flat substrate
journal, April 2009