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)

Abstract

The influence of gas diffusion layer (GDL) design parameters on the performance of a polymer electrolyte fuel cell (PEFC) was evaluated using a test apparatus in which the clamp pressure on the cell could be accurately controlled. The PEFC performance varies significantly depending on the humidity of the supplied gas. Under moderate humidity, the PEFC performance is enhanced when using an untreated GDL with high air permeability. Under high humidity, improved performance is achieved using a GDL with PTFE hydrophobic treatment. A microporous layer (MPL) coated GDL significantly reduces flooding on the electrode, resulting in a decrease in the concentration overpotential. This enhances the PEFC performance at high current densities. A substrate with high air permeability for the MPL coated GDL enhances the ability of the MPL to prevent flooding. Under low humidity, the MPL is also effective to prevent drying-up of the membrane electrode assembly (MEA), resulting in enhanced performance. A substrate with low air permeability for the MPL coated GDL is effective for the prevention of drying-up.

Hydrophilic and Hydrophobic Double MPL Coated GDL to Enhance PEFC Performance under Low and High Humidity Conditions

“…The design parameters for the GDL, such as thickness, pore size, electrical resistivity, gas permeability and hydrophobic and hydrophilic properties, play an important role in determining the characteristics of electron transport, gas diffusion and water management during PEFC operation. Several investigations have demonstrated that a hydrophobic microporous layer (MPL) coated on the GDL substrate is effective for improvement of the water management characteristics, thereby enhancing PEFC performance (4)(5)(6)(7)(8). An optimum MPL coated GDL significantly reduces flooding on the electrode under high humidity and also prevents dehydration of the MEA under low humidity.…”

Influence of Hydrophilic and Hydrophobic Double MPL Coated GDL on PEFC Performance without Cathode Humidification

“…Several investigations have demonstrated that a hydrophobic microporous layer (MPL) coated on the GDL substrate is effective for improvement of the water management characteristics, thereby enhancing PEFC performance (4)(5)(6). The authors have also reported that an optimum MPL coated GDL significantly reduces flooding on the electrode under high humidity conditions and also prevents dehydration of the MEA under low humidity conditions (7)(8)(9)(10). Both reducing pore diameter and lowering the hydrophobicity of the MPL is effective for the prevention of MEA dehydration, thereby enhancing PEFC performance under low humidity.…”