Microporous layer-coated gas diffusion layer for performance enhancement of polymer electrolyte fuel cells without humidification using anode gas recirculation

The present study examined the effect of anode gas recirculation on the performance of a polymer electrolyte fuel cell (PEFC) without humidification. Increasing the gas flow velocity to 2 m s^-1 by increasing the anode gas recirculation promotes water transport from the anode gas to the membrane. Decreasing the pore diameter of a microporous layer (MPL)-coated gas diffusion layer (GDL) is effective at preventing membrane dehydration, which enhances PEFC performance without humidification. The oxygen transport resistances are measured using the limiting current density values. Decreasing the MPL pore diameter raises the water breakthrough pressure, increasing the oxygen transport resistance under high humidity conditions. When employing an MPL containing hydrophilic carbon nanotubes, it is possible to decrease the pore diameter without raising the water breakthrough pressure. This is therefore an effective means of reducing the oxygen transport resistance under high humidity conditions, compared with that obtained when using a hydrophobic MPL.