On the current distribution at the channel - rib scale in polymer-electrolyte fuel cells

Experimental results based on in-situ measurements at the interface between the catalyst layer and the gas diffusion layer (GDL) on the cathode side at the channel - rib scale show an interesting variation of the current density distribution as the mean current density is increased. It is found that the local current density below the rib median axis corresponds to a maximum at low to intermediate mean current densities and to a minimum when the mean current density is sufficiently high. Also, the higher is the current density, the more marked the minimum. From numerical simulations, it is shown that the current density distribution inversion phenomenon is strongly correlated to the liquid water zone development within the GDL.