Measurement of effective oxygen diffusivity in electrodes for proton exchange membrane fuel cells

✍ Scribed by Zhiqiang Yu; Robert N. Carter

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 631 KB
• Volume: 195
• Category: Article
• ISSN: 0378-7753
• DOI: 10.1016/j.jpowsour.2009.08.065

✦ Synopsis

This paper describes a novel method to measure directly effective diffusivity in electrodes as a function of temperature and relative humidity (RH) at conditions that are relevant for proton exchange membrane fuel cells (PEMFCs). The efficacy of this method to measure effective oxygen diffusivity (D

) is demonstrated with measurements of a series of electrodes of varying the ionomer-to-carbon weight ratio (I/C ratio). The measured D eff O 2 decreases sharply with increasing I/C ratio from 0.5 to 1.5 at the same RH, and reduces gradually with increasing RH from 0% to 100% at the same I/C ratio. The measured D eff O 2 is considerably smaller than the calculated one using the Bruggeman correction, indicating the Bruggeman correction drastically underestimates the tortuosity with increasing I/C ratio in PEMFC electrodes.