Single Cell Study of Water Transport in PEMFCs with Electrosprayed Catalyst Layers

Abstract

AbstractWater transport in proton exchange membrane fuel cells (PEMFCs) with electrosprayed catalyst layers is analyzed by means of water collection measurements. With this aim, single cells have been studied with different catalyst layers configuration: electrosprayed layer in cathode (EScat), in anode (ESan), and in both electrodes (ESboth). The electrosprayed catalyst layers show macroporous morphology and superhydrophobicity (water contact angle θ > 150°) . Initial polarization curves, taken after a few hours from cell start‐up, show above 20% higher maximum power density of EScat and ESan cells, compared with a conventional cell (with no electrosprayed layers). The performance improvement is due to lower internal resistance of the cell according to the polarization curves. Stability of the cells under the dry‐gas operation conditions used during water collection measurements, shows to be high only for EScat, whereas ESan, ESboth, and conventional cells suffer degradation and frequent membrane failure. Water collection experiments at variable temperature and current density reflect larger water flow towards the anode for EScat cell than for the other configurations. It is concluded that the high performance and stability of EScat is due to the enhanced water back diffusion from cathode to anode driven by the superhydrophobic electrosprayed catalyst layer in cathode. Favored back diffusion improves water balance in the cell, membrane humidification, decreases the internal resistance, and precludes anode drying and cathode flooding. The optimal cell configuration is obtained with an electrosprayed catalyst layer in the cathode and a standard hydrophilic catalyst layer in the anode.