Hydrophilic and Hydrophobic Composite Microporous Layer Coated Gas Diffusion Layer to Reduce Oxygen Transport Resistance of Polymer Electrolyte Fuel Cell

Polymer electrolyte fuel cells (PEFCs) effectively reduce greenhouse gas (GHG) emissions across various transportation industries. To meet the demands of commercial applications, PEFCs should be designed to deliver higher voltage at elevated current densities, making the minimization of oxygen transport resistance essential for optimizing their performance. The microporous layer (MPL)-coated gas diffusion layer (GDL) is key in optimizing water management and minimizing oxygen transport resistance. A novel composite MPL, combining the less-hydrophobic and hydrophobic pores on a thin carbon mesh, has been developed to enhance performance by lowering oxygen transport resistance. Water permeability tests were used to determine the hydrophobic and hydrophilic permeability ratios in the composite MPL, providing insights into their roles in water distribution and oxygen transport. Ultimately, the separations of pressure-independent and pressure-dependent oxygen transport resistances from the total oxygen transport resistance were conducted under 80%RH and 200%RH conditions for hydrophobic, hydrophilic, and composite MPL-coated GDLs. The composite MPL demonstrated superior performance by effectively reducing total oxygen transport resistance under both normal and high humidity conditions, achieving a balanced gas-liquid transport and improving PEFC performance.