Newsletter  2012.9  Index

Theme : "Flow in Fuel Cells"   Preface (M. Ogino, M. Oshima, S. Tamano) Visualization of Liquid Water Behaviors in PEFCs by Soft X-ray Radiography Shohji TSUSHIMA, Shuichiro HIRAI (Tokyo Institute of Technology) Measurement and analysis methods of oxygen diffusivity for PEMFC components Norio KUBO, (Fuel Cell Cutting-Edge Research Center, Technology Research Association) Effects of supplied gas humidity change on PEFC transient power generation Takuto ARAKI (Yokohama National University) Numerical simulation and evaluation for developing next generation fuel cells Yuya TACHIKAWA (Kyushu University) Transport Phenomena in Polymer Electrolyte Fuel Cell by Molecular Dynamics Method Takashi TOKUMASU (Tohoku University)   |  Back  |

 

Measurement and analysis methods of oxygen diffusivity for PEMFC components

Norio KUBO, Fuel Cell Cutting-Edge Research Center, Technology Research Association

Abstract

Polymer Electrolyte Membrane Fuel Cell (PEMFC) is regarded as an alternative clean energy source for automobile applications. Key challenges to the acceptance of PEMFC for automobile application are the cost reduction and improvement in power density for its compactness. In particular, higher current density operation is one of the promising solutions to realize the cost reduction. However, higher current density operation requires more reactants flux for electrochemical reaction in catalyst layer. So, the transport phenomena have great impacts on the cell performance. And, oxygen transport resistance in gas diffusion layer, micro porous layer and catalyst layer are known to have great impact on the cell performance. However, regardless of its importance, oxygen transport phenomena in the PEMFC components are not yet fully understood because of its complexity.

In this study, measurement and analysis methods such as quantification of oxygen diffusivity, visualization/reconstruction of porous structure and prediction of oxygen diffusivity based on the reconstructed real structures were developed and applied to characterization of PEMFC components. As the result, the oxygen diffusion resistances of each PEMFC component amounted to approximately equivalent order. So, to realize higher current density operation, it is necessarily to reduce the oxygen diffusion resistances of all components such as gas diffusion layer, micro porous layer and catalyst layer. And the predicted values of oxygen diffusion resistance agreed with the measured values. This analytical results substantiated availability and accuracy of the methods for PEMFC components. It is expected that innovative technologies will be created based on the deeper understanding of oxygen transport phenomena by using developed technologies.

Key Words

Polymer Electrolyte Membrane Fuel Cell, mass transport, gas diffusion, porous media

Figures

Fig. 1 Oxygen diffusion resistance of component for PEFCs (Temperature: 22℃)

Fig.2 3D structure of gas diffusion layer reconstructed by micro X-ray CT technique

Fig.3 3D structure of micro porous layer reconstructed by nano X-ray CT technique	Fig.4 Oxygen transport properties (Experimental vs. Prediction)