Localised electrochemical impedance measurements of a polymer electrolyte fuel cell using a reference electrode array to give cathode-specific measurements and examine membrane hydration dynamics

Erik Engebretsen, Gareth Hinds, Quentin Meyer, Tom Mason, Edward Brightman, Luis Castanheira, Paul R. Shearing, Daniel J.L. Brett

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Advances in bespoke diagnostic techniques for polymer electrolyte fuel cells continue to provide unique insight into the internal operation of these devices and lead to improved performance and durability. Localised measurements of current density have proven to be extremely useful in designing better fuel cells and identifying optimal operating strategies, with electrochemical impedance spectroscopy (EIS) now routinely used to deconvolute the various losses in fuel cells. Combining the two techniques provides another dimension of understanding, but until now each localised EIS has been based on 2-electrode measurements, composed of both the anode and cathode responses. This work shows that a reference electrode array can be used to give individual electrode-specific EIS responses, in this case the cathode is focused on to demonstrate the approach. In addition, membrane hydration dynamics are studied under current load steps from open circuit voltage. A three-stage process is identified associated with an initial rapid reduction in membrane resistance after 10 s of applying a current step, followed by a slower ramp to approximately steady state, which was achieved after ∼250 s. These results support previously published work that has looked at membrane swelling dynamics and reveal that membrane hydration/membrane resistance is highly heterogeneous.

Original languageEnglish
Pages (from-to)38-44
Number of pages7
JournalJournal of Power Sources
Volume382
Early online date22 Feb 2018
DOIs
Publication statusPublished - 1 Apr 2018

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Keywords

  • entrance length
  • localised electrochemical impedance spectroscopy
  • membrane resistance transients
  • polymer electrolyte fuel cell
  • reference electrode
  • water management

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