Effect of Hydrophobic Particles in a Gas Diffusion Electrode on Cell Performance in Polymer Electrolyte Membrane Fuel Cells

The relationship between cell performance and the hydrophobic properties of a catalytic layer containing hydrophobic particles in a gas diffusion electrode for a polymer electrolyte membrane fuel cell was investigated. The hydrophobic particles, prepared from carbon black and polytetrafluoroethylene dispersion, were added to a catalytic layer to form a gas diffusion network by enhancing the hydrophobic property of the catalytic layer. The cell performance increased as the catalytic layer became more hydrophobic. A more hydrophobic catalytic layer reduced blockage of the gas diffusion path that water, reaction product, caused. Water was produced by the electrochemical reaction of the reactant gases at the catalytic layer. The hydrophobic property of the catalytic layer was more important at the high current density region compared with the low current density region. A three-layered electrode system with a test layer and catalytic layer were used to investigate the flux of humidified gas through the catalytic layer. The hydrophobic nature of the test layer determined by the amount of hydrophobic particles in the catalytic layer influenced the gas flux and changed the cell performance.