PEMFC modeling based on characterization of effective diffusivity in simulated cathode catalyst layer |
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Authors: | Young-Jun Sohn Sung-Dae Yim Gu-Gon Park Minjin Kim Suk-Won Cha Kyoungyoun Kim |
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Affiliation: | 1. Fuel Cell Research Center, New and Renewable Energy Research Division, Korea Institute of Energy Research (KIER), Daejeon, 305-343, Republic of Korea;2. Advanced Energy Technology, University of Science and Technology, Daejeon, Republic of Korea;3. School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, 151-742, Republic of Korea;4. Department of Mechanical Engineering, Hanbat National University, Daejeon, 305-719, Republic of Korea |
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Abstract: | Oxygen diffusion in the cathode catalyst layer (CCL) is crucial to the high performance of polymer electrolyte membrane fuel cells (PEMFCs), especially in high current density or concentration loss regions. Recently, PEMFC performance has been reported to be enhanced by increasing CCL pore size and pore volume due to the reduction of diffusion resistance by capillary water equilibrium Yim et al., Electrochimica Acta 56 (2011) 9064–9073]. Herein, we simulate these experimental results utilizing a new one-dimensional PEMFC model considering the effects of accumulated water film in CCL on oxygen diffusion. Two CCL microstructures were numerically generated based on agglomerate models to examine the experimental results obtained for two membrane electrode assembly (MEA) samples with different CCL porosity. The effective diffusivity of oxygen in the CCL was estimated by performing auxiliary simulations of oxygen concentration in CCL microstructures covered by a film of liquid water, with exponential correlation obtained between effective diffusivity and the thickness of the above film. Polarization curves predicted by the present model were in good agreement with experimental results. In agreement with the results of Yim et al., the present model predicts that the MEA featuring a CCL with smaller pores (which are more easily filled by liquid water) should exhibit a larger concentration loss at high current densities. |
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Keywords: | PEMFC Cathode catalyst layer Simulated or stochastic catalyst layer microstructure Effective diffusion coefficient Water film thickness |
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