Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • 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
Accelerated degradation of bipolar plates in the PEMFC
KTH, School of Chemical Science and Engineering (CHE).
2016 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Accelererad nedbrytning av bipolära plattor i en PEMFC (Swedish)
Abstract [en]

The aging of bipolar plates in the polymer electrolyte membrane fuel cell was evaluated using different accelerated degradation tests. From previous studies, it is well known that the startups and shutdowns of a polymer electrolyte membrane fuel cell is the primary cause of fuel cell component degradation. Therefore, the aim of these tests was to simulate the number of startups/shutdowns that normally occur during the lifetime of a polymer electrolyte membrane fuel cell, e.g. for automobile applications. The tests were carried out in situ in order to be as realistic and close to operational conditions in real applications as possible. Mechanical stress and degradation normally occurring during polymer electrolyte membrane fuel cell operation was thereby included. The accelerated degradation tests were designed for maximum fuel cell stress, including use of the no purge and the air purge strategy, short cycle duration as well as an increased number of startups/shutdowns. Since the no purge strategy avoids prevention of local H

2/O2 fronts, this strategy was implemented first. Other strategies e g the air purge strategy, where air is used to purge the anode, where also implemented. Parameters influencing the tests were varied and the cathode gas was changed between O2 and air depending on the test. Electrochemical methodology was implemented for the detection of corrosion in the tests and for analysis/ studies of the test results. These techniques include cell voltage/current readings, polarization curves, electrochemical impedance spectroscopy, contact resistance and current density decrease at constant cell voltage. In addition, scanning electron microscope was used to visualize the actual corrosion of the bipolar plates. It was found that implementation of the air purge strategy resulted in localized corrosion, i.e. oxide film formation, on the surface of the bipolar plates increasing both the corrosion resistance and the interfacial contact resistance.

Abstract [sv]

Åldrandet av bipolära plattor i polymerelektrolytbränslecellen undersöktes med hjälp av olika accelererade nedbrytningstest. Från tidigare studier är det känt att uppstarterna och avstängningarna av denna typ av bränslecell är den främsta orsaken till nedbrytningen av bränslecellskomponenterna. Av den anledningen var syftet med dessa test att simulera antalet uppstarter och avstängningar som normalt sker under en polymerelektrolytbränslecells livstid t ex för tillämpningar i fordon. Testen utfördes in situ för att vara så realistiska och så nära driftsförhållandena i verkliga tillämpningar som möjligt. Därmed inkluderades mekanisk påfrestning och nedbrytning som normalt sker under drift i en polymerelektrolytbränslecell. De accelererade nedbrytningstesterna utformades för maximal bränslecellspåfrestning. Detta åstadkoms bl a genom tillämpning av den s k "no purge"och "air purge " strategin, kort cykeltid samt ett utökat antal uppstarter/avstängningar. Eftersom "no purge" strategin eliminerar förebyggandet av H

2/O2 fronter, testades denna strategi först. Andra strategier tillämpades också som t ex "air purge" strategin, där luft fick "rena" anodsidan. Parametrar som påverkar testen varierades och katodgasen skiftades mellan O2 och luft beroende på experimentet. Elektrokemisk metodik användes för att detektera nedbryning i de olika testen och för att studera testresultaten. Dessa tekniker omfattade cellspänning/ -ström mätningar, polarisationskurvor, elektrokemisk impedans spektroskopi, kontaktresistens och strömtäthetsminskning vid konstant cellspänning. Svepelektronmikroskopi användes för att visualisera den fysiska nedbryningen av de bipolära plattorna. Det visade sig att "air purge" strategin gav upphov till korrosion i form av lokal oxidbildning på de bipolära plattornas yta. Detta ökade både korrosionsmotståndet och kontaktresistensen i gränsskiktet.

Place, publisher, year, edition, pages
2016.
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-207367OAI: oai:DiVA.org:kth-207367DiVA: diva2:1096860
Available from: 2017-05-19 Created: 2017-05-19 Last updated: 2017-05-19Bibliographically approved

Open Access in DiVA

fulltext(1566 kB)2364 downloads
File information
File name FULLTEXT01.pdfFile size 1566 kBChecksum SHA-512
efeead05e3920f706ce365d6c0e231dfed3d138a1cdf4eedabcaf9b833f588665396909b920d6c20b7366e88fae82b3c78dc0e73e5779c62f3203e037d82b610
Type fulltextMimetype application/pdf

By organisation
School of Chemical Science and Engineering (CHE)
Chemical Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 2364 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 66 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • 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