On the effect of gas diffusion layers hydrophobicity on direct methanol fuel cell performance and degradation

Degradation and mass transport phenomena management are two of the main issues hindering direct methanol fuel cell commercialization. Water and methanol crossover through the membrane, regulated by both anode and cathode gas diffusion layers hydrophobic properties, is widely studied in the literature, while the effect of mass transport phenomena evolution on the direct methanol fuel cell degradation has not been investigated yet. This work aims to present a combined experimental and modeling analysis on the effect of the gas diffusion layers hydrophobicity on DMFC degradation, through the comparison of performance characterization and degradation tests of two different fuel cells. In one of them, the lower diffusion layer hydrophobicity and the absence of anode microporous layer determines the onset of cathode flooding, negatively affecting performance and degradation. However, the cathode surface area loss is similar between the two fuel cells, meaning that flooding does not involve modifications in cathode permanent degradation mechanisms, but it mainly determines the amplification of the cathode surface area loss effects.