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

• Published in: International journal of hydrogen energy Vol. 35; no. 23; pp. 13104 - 13110
• Main Authors: Kim, Kun-Ho, Lee, Kwan-Young, Lee, Sang-Yeop, Cho, EunAe, Lim, Tae-Hoon, Kim, Hyoung-Juhn, Yoon, Sung Pil, Kim, Sae Hoon, Lim, Tae Won, Jang, Jong Hyun
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2010; Elsevier
• Subjects: Alternative fuels. Production and utilization; Applied sciences; CCM (catalyst-coated membrane) spraying method; Energy; Exact sciences and technology; Fuels; Hydrogen; MEA (membrane-electrode assembly); Nafion ® ionomer; PEMFC (polymer electrolyte membrane fuel cell); Relative humidity; Relative humidity; Nafion ® ionomer; PEMFC (polymer electrolyte membrane fuel cell); CCM (catalyst-coated membrane) spraying method; MEA (membrane-electrode assembly); Water management; Polymer electrolytes; Cathode; Hydrogen; Spraying; Ionic conductivity; ionomer; Activation; Nafion; Proton conductivity; Membrane; Performance; Catalyst; Fuel cell
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2010.04.082

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 (38–87%) 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/cm 2 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/cm 2 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%.