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Research Papers

# Performance Improvement of a Proton Exchange Membrane Fuel Cell Through the Electrode Structure Change

[+] Author and Article Information
Ming-San Lee, Long-Jeng Chen, Ting-Huai Chen

Fuel Cell Laboratory, Department of Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan

J. Fuel Cell Sci. Technol 6(1), 011006 (Nov 04, 2008) (5 pages) doi:10.1115/1.2971048 History: Received March 29, 2007; Revised November 02, 2007; Published November 04, 2008

## Abstract

A new hydrophobic micropillared structure for the electrode of a proton exchange membrane fuel cell (PEMFC) is proposed in this study. Its performance has a 40% increase over the conventional structured electrode. The new design changes the gas-diffusion layer (also called microporous layer (MPL)) of the cathode of a PEMFC to a gas-abundant-layer (GAL) by mixing a high percentage of polytetrafluoroethylene (PTFE) into the carbon powder. Unlike the generally flat MPL, the surface of the GAL in contact with the catalyst layer has tens of thousands of micropillars on top of it so that its area can be increased significantly. The interfacial region between the GAL and the catalyst layer will become the main reaction sites because the heavily PTFE treated GAL will be filled with oxygen passageways while most of the catalyst layer of the cathode will eventually be filled with the water produced in the operation. The experimental results with different pillar sizes have shown that the area of the interfacial surface between the GAL and the catalyst layer is the key factor in determining the cell performance and should be made as large as possible.

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## Figures

Figure 1

The structure of MEAs: (a) conventional with MPL (GDL) and (b) the HMPS

Figure 2

Manufacturing processes of the HMPS electrode includes the following: (1) coat the surface of carbon cloth with PTFE-C; (2) flatten the coating so that microstructure may be built; (3) spray PTFE-C through a mask to build the HMPS; (4) remove the mask when desired pillar height is reached; (5) spray the catalyst onto the GAL

Figure 3

The microscopic photo of the GAL with micro pillars (55×55×20μm3)

Figure 4

Performance comparison between the HMPS and the MPL electrodes

Figure 5

Performance comparison between the HMPS and the MPL electrodes with current density on a natural log scale

Figure 6

Performance comparison between the HMPS and the MPL electrodes. The current density of the latter is multiplied by the interfacial area ratio (=1.4) of the two

Figure 7

Performance comparison between electrodes with larger pillars and shorter pillars

Figure 8

Performance comparison between the HMPS (larger pillars) and the MPL electrodes. The current density of the latter is multiplied by the interfacial area ratio (=1.2) of the two

Figure 9

Figure 10

Schematic of the active and inactive catalyst at higher output current

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