Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Steady-state and EIS investigations of hydrogen electrodes and membranes in polymer electrolyte fuel cells: II. Experimental
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.ORCID iD: 0000-0001-9203-9313
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
2006 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, Vol. 153, no 4, A759-A764 p.Article in journal (Refereed) Published
Abstract [en]

Influence of water on membrane and anode performance was studied with steady-state and electrochemical impedance spectroscopy (EIS) measurements using a symmetrical cell with hydrogen on both sides. Both full-cell and half-cell measurements were performed. To obtain half-cell data a new reference electrode approach was demonstrated based on porous references in a four-electrode setup. A varying membrane resistance with current density was obtained using current interrupt and EIS measurements. The EIS measurements showed two semicircles at 10(4) Hz and 0.01-0.1 Hz, respectively. The first corresponds to hydrogen adsorption and the second to the water dependence of the electrode performance and membrane resistance. The low-frequency semicircle appears in a frequency range depending on the membrane thickness. The loop corresponding to the discharge of the double-layer capacitance through the Volmer reaction appears at frequencies too high to be experimentally measurable. The experimental data were in good agreement with the model developed in Part I of this paper. The model was also successfully fitted to experimental full cell data at different current densities and membrane thicknesses. The experiments confirmed that the low-frequency semicircle is attributed to the water dependence of both anode and membrane performance.

Place, publisher, year, edition, pages
2006. Vol. 153, no 4, A759-A764 p.
Keyword [en]
Current density, Electric currents, Electrodes, Frequencies, Fuel cells, Hydrogen, Polyelectrolytes, Porosity, Water
National Category
Inorganic Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-10084DOI: 10.1149/1.2172561ISI: 000235723600018Scopus ID: 2-s2.0-33644790292OAI: oai:DiVA.org:kth-10084DiVA: diva2:207514
Note
QC 20101104Available from: 2009-03-12 Created: 2009-03-11 Last updated: 2010-11-04Bibliographically approved
In thesis
1. Modelling and Experimental Investigation of the Dynamics in Polymer Electrolyte Fuel Cells
Open this publication in new window or tab >>Modelling and Experimental Investigation of the Dynamics in Polymer Electrolyte Fuel Cells
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In polymer electrolyte fuel cells (PEFC) chemical energy, in for example hydrogen, is converted by an electrochemical process into electrical energy. The PEFC has a working temperature generally below 100 °C. Under these conditions water management and transport of oxygen to the cathode are the parameters limiting the performance of the PEFC.

The purpose of this thesis was to better understand the complex processes in different parts of the PEFC. The rate-limiting processes in the cathode were studied using pure oxygen while varying oxygen pressure and humidity. Mass-transport limitations in the gas diffusion layer using oxygen diluted in nitrogen or helium was also studied. A large capacitive loop was seen at 1-10 Hz with 5-20 % oxygen. When nitrogen was changed to helium, which has a higher binary diffusion coefficient, the loop decreased and shifted to a higher frequency.

Steady-state and electrochemical impedance spectroscopy (EIS) models have been developed that accounts for water transport in the membrane and the influence of water on the anode. Due to water drag, the membrane resistance changes with current density. This gives rise to a low frequency loop in the complex plane plot. The loop appeared at a frequency of around 0.1 Hz and varied with D/Lm2, where D is the water diffusion coefficient and Lm is the membrane thickness. The EIS model for the hydrogen electrode gave three to four semicircles in the complex plane plot when taking the influence of water concentration on the anode conductivity and kinetics into account. The high-frequency semicircle is attributed to the Volmer reaction, the medium-frequency semicircle to the pseudocapacitance resulting from the adsorbed hydrogen, and the low-frequency semicircles to variations in electrode performance with water concentration. These low-frequency semicircles appear in a frequency range overlapping with the low-frequency semicircles from the water transport in the membrane. The effects of current density and membrane thickness were studied experimentally. An expected shift in frequency, when varying the membrane thickness was seen. This shift confirms the theory that the low-frequency loop is connected to the water transport in the membrane.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2009. 46 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2009:6
Keyword
polymer electrolyte fuel cell, modelling, electrochemical impedance spectroscopy, water transport, membrane
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-10087 (URN)978-91-7415-241-8 (ISBN)
Presentation
2009-04-03, D2, Lindstedtsvägen 5, KTH, Stockholm, 10:15 (Swedish)
Opponent
Supervisors
Note

QC 20121011

Available from: 2009-03-18 Created: 2009-03-11 Last updated: 2012-10-11Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Authority records BETA

Lindbergh, Göran

Search in DiVA

By author/editor
Wiezell, KatarinaLindbergh, GöranGode, Peter
By organisation
Chemical Engineering and Technology
In the same journal
Journal of the Electrochemical Society
Inorganic Chemistry

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 57 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf