Experimental investigation of current distributions in a direct methanol fuel cell with various gas diffusion layers and Nafion membranes

The influences of the gas diffusion layer (GDL) properties on the current distributions of a direct methanol fuel cell are investigated. Cathode GDLs with different hydrophobicity/hydrophilicity, air permeability, microporous layer (MPL), thickness, and texture properties are examined. Among the GDLs examined, a thin hydrophobic GDL with an MPL has the most homogeneous current distribution, which is primarily ascribed to the better water management capabilities of the cathode GDL properties. The differences in the current distribution among the different GDLs are more apparent when the air flow rate and loaded current are lower. The effect of the membrane thickness on the current distributions is also investigated. Among the membranes examined, Nafion^® 112 has different current distributions from the others, whereas there is no noticeable difference between the current distributions with Nafion^® 115 and Nafion^® 117. The current distribution with Nafion^® 112 is most affected by the enhanced methanol crossover and the high mixed potential.