The effects of relative humidity on the performances of PEMFC MEAs with various Nafion ionomer contents

Title
The effects of relative humidity on the performances of PEMFC MEAs with various Nafion ionomer contents
Authors
김근호이관영이상엽조은애임태훈김형준윤성필김세훈임태원장종현
Keywords
PEMFC; MEA; Relative humidity; Nafion ionomer; CCM (catalyst-coated membrane)
Issue Date
2010-12
Publisher
International journal of hydrogen energy
Citation
VOL 35, NO 23, 13104-13110
Abstract
For PEMFC operation, water management is very important to provide both sufficient proton conductivity and mass transport. Therefore, in this study, the effect of the relative humidity (38e87%) on cell performance is examined for PEMFC MEAs with various Nafion ionomer contents. The MEAs were fabricated using a CCM (catalyst-coated membrane) spraying method. As the relative humidity of the cathodes (RHC) increases, the cell voltages at 0.4 and 1.2 A/cm2 increased for a MEA with 20 wt% ionomer. This can be explained in terms of the expansion of active sites with enhanced ionic conductivity (activation overpotential). In contrast, with a higher RHC value, the cell voltages for 35 wt% ionomer (more hydrophilic) gradually decreased as a result of slower gas transport (concentration overpotential). For MEAs with intermediate ionomer contents, 25 and 30 wt%, the cell voltages at 0.4 A/cm2 showed maximum values at a RHC of 67%, at which point the mass transport begins to be the more dominant factor. The highest unit cell performance was observed in a MEA with an ionomer content of 25 wt% at a RHC of 59% and in a MEA at 20 wt% ionomer content at a higher humidity of 87%.
URI
http://pubs.kist.re.kr/handle/201004/39252
ISSN
0360-3199
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