Effects of design parameters in paper type gas diffusion layer on the performance of polymer electrolyte fuel cells (measures to prevent flooding and drying-up)

The experiments to understand the dependency of the gas diffusion layer (GDL) design parameters on the performance of polymer electrolyte fuel cells (PEFCs) were carried out using the test apparatus in which the clamp pressure of the cell could be controlled. The behavior of the PEFC performance was highly influenced by the humidity of the supplied gas. Under high-humidity conditions, the hydrophobic treatment to the GDL substrate improved the PEFC performance with reducing the flooding magnitude, resulting in decreasing concentration overpotential. Much higher effect to prevent the flooding was achieved with putting a microporous layer (MPL). Under low-humidity conditions, both of the hydrophobic treatment and the MPL worked to prevent drying-up of the MEA, resulting in minimizing IR, activation and concentration overpotentials. The MPL coating substrate with larger air permeability was better to prevent the flooding, and the substrate with the smaller air permeability was better to prevent the drying-up.