Title: Elucidating the impact of the ionomer equivalent weight on a platinum group metal-free PEMFC cathode via oxygen limiting current

Abstract

Leveraging the interactions between ionomer and catalyst can increase the performance of proton exchange membrane fuel cells. The impacts of the equivalent weight (EW) of perfluorosulfonic acid–based ionomers on the platinum group metal-free electrode structure and fuel cell performance have not been fully explored. Four membrane electrode assemblies (MEAs) were prepared by using a commercial Fe–N–C catalyst, two perfluorosulfonic acid ionomers with different EWs, that is, Aquivion 720 (A720) and Nafion 1100 (N1100), and two ionomer-to-catalyst (I/C) ratios. The four MEAs were characterized to understand the impact of the ionomer EW and content on the capacitance, proton conductivity, and mass transport on the cathode. The mass transport resistance was measured for the first time using a new oxygen reduction reaction limiting current method enabling to couple the effects of oxygen diffusion with liquid water generation. Low EW ionomer combined with a moderate I/C results in improved performance due to its enhanced proton conductivity. However, when used at high I/C, it can cause severe water flooding at high current density due to the enhanced liquid water uptake, especially at high relative humidity, resulting in lower catalyst utilization and higher mass transport resistance.

Authors:

Wang, Hao ^[1]; Osmieri, Luigi  ^[1];

• Search DOE PAGES for author "Osmieri, Luigi"
• Search DOE PAGES for ORCID "0000-0002-3111-2270"

Yu, Haoran  ^[2];

• Search DOE PAGES for author "Yu, Haoran"
• Search DOE PAGES for ORCID "0000-0001-7304-2840"

Zachman, Michael J.  ^[2];

• Search DOE PAGES for author "Zachman, Michael J."
• Search DOE PAGES for ORCID "0000-0003-1910-1357"

Park, Jae Hyung ^[3]; Kariuki, Nancy N. ^[3]; Cetinbas, Firat C. ^[3]; Khandavalli, Sunilkumar  ^[1];

• Search DOE PAGES for author "Khandavalli, Sunilkumar"
• Search DOE PAGES for ORCID "0000-0003-3179-5718"

Mauger, Scott ^[1]; Myers, Deborah J. ^[3]; Cullen, David A.  ^[2];

• Search DOE PAGES for author "Cullen, David A."
• Search DOE PAGES for ORCID "0000-0002-2593-7866"

Neyerlin, Kenneth C. ^[1]

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+ Show Author Affiliations

1. National Renewable Energy Laboratory (NREL), Golden, CO (United States). Chemistry and Nanoscience Center
2. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
3. Argonne National Laboratory (ANL), Lemont, IL (United States)

Publication Date:

Mon Dec 26 00:00:00 EST 2022

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States); Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC)

Contributing Org.:

Electrocatalysis Consortium (ElectroCat)

OSTI Identifier:

1908040

Alternate Identifier(s):

OSTI ID: 1959960

Report Number(s):

NREL/JA-5900-85471
Journal ID: ISSN 2692-4552

Grant/Contract Number:  

AC05-00OR22725; AC36-08GO28308; AC02-06CH11357

Resource Type:

Accepted Manuscript

Journal Name:

SusMat (Online)

Additional Journal Information:

Journal Name: SusMat (Online); Journal Volume: 3; Journal Issue: 1; Journal ID: ISSN 2692-4552

Publisher:

Wiley

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; ionomer equivalent weight; limiting current; mass transport; oxygen reduction reaction; PGM-free catalyst; proton exchange membrane fuel cell