Optimization of Cathode Flooding in Scaled-up Microfluidic Fuel Cells

The scaling up of microfluidic fuel cells (MFC) with enlarged electrode area can be very advantageous for their stacking, which will, however, aggravate the cathode flooding problem due to the intensified fuel crossover. In this paper, we first validate the cathode flooding phenomenon in a scaled-up MFC prototype which has a hydrogen-breathing anode and an air-breathing cathode. To optimize the flooding issue, cracking the cathode catalyst layer is found to be remarkably effective. The cathode outer surface is found to be free from water after six polarization cycles, and the degradation rate of current density is as low as 1.3mAcm^-2h^-1 when the cell is discharged at 0.4 V for five hours. This is probably attributed to the pressure variation inside the cathode induced by the cracks, which alters the water transport direction from gas diffusion layer to the electrolyte channel.