Title: Nanofiber Fuel Cell MEAs with a PtCo/C Cathode

Abstract

PtCo/C and Pt/C catalyst powders were incorporated into electrospun nanofiber and conventional sprayed cathode membrane-electrode-assemblies (MEAs) at a fixed electrode loading of 0.1 mgPt/cm². The binder for PtCo/C nanofiber cathodes and Pt/C nanofiber anodes was a mixture of Nafion and poly(acrylic acid) (PAA), whereas the sprayed electrode MEAs utilized a neat Nafion binder. The structure of electrospun fibers was analyzed by scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDS), which showed that the fibers were ~30% porous with a uniform distribution of catalyst and binder in the axial and radial fiber directions. The initial performance of nanofiber MEAs at 80°C was 20% better than the sprayed electrode MEA (a maximum power density of 1,045 mW/cm² vs. 869 mW/cm²). The benefit of the nanofiber electrode morphology was most evident at end-of-test (after a metal dissolution accelerated stress test), where power densities dropped by only 8%, after 30,000 square wave voltage cycles (0.6 V to 0.95 V), as compared to a 35% drop in the maximum power for the sprayed electrode MEA. The use of a recovery protocol improved the initial performance of a nanofiber MEA by ~13%, to 1,070 mW/cm² at 0.65 V, and increased the power after amore » metal dissolution stress test by 5–10% (e.g. 840 mW/cm² at 0.65 V after 30,000 voltage cycles). At rated power, the nanofiber MEA generated more than 1,000 mW/cm² at 99°C and a pressure of 250 kPa_abs. The high performance and durability of PtCo/C nanofiber cathode MEAs is due to the combined effects of a highly active cathode catalyst and the unique nanofiber electrode morphology, where there is a uniform distribution of catalyst and binder (no agglomeration) and short transport pathways across the submicron diameter fibers (which lowers gas transfer resistance and facilitates water removal from the cathode).« less

Authors:

Slack, J. J.; Gumeci, C.; Dale, N.; Parrondo, J.; Macauley, N. ;

• Search DOE PAGES for author "Macauley, N."
• Search DOE PAGES for ORCID "0000-0001-5602-0092"
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Mukundan, R. ;

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• Search DOE PAGES for ORCID "0000-0002-5679-3930"
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Cullen, D.; Sneed, B.; More, K. ;

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• Search DOE PAGES for ORCID "0000-0001-5223-9097"
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Pintauro, P. N.

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• Search DOE PAGES for ORCID "0000-0001-5115-7276"
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Publication Date:

2019-04-22

Research Org.:

Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Transportation Office. Fuel Cell Technologies Office

OSTI Identifier:

1508200

Alternate Identifier(s):

OSTI ID: 1525856; OSTI ID: 1531230

Report Number(s):

LA-UR-19-21920
Journal ID: ISSN 0013-4651; /jes/166/7/F3202.atom

Grant/Contract Number:  

EE0007653; 89233218CNA000001; AC05-00OR22725

Resource Type:

Published Article

Journal Name:

Journal of the Electrochemical Society

Additional Journal Information:

Journal Name: Journal of the Electrochemical Society Journal Volume: 166 Journal Issue: 7; Journal ID: ISSN 0013-4651

Publisher:

The Electrochemical Society

Country of Publication:

United States

Language:

English

Subject:

25 ENERGY STORAGE; Energy Sciences; Fuel Cells - PEM; electrospinning