Improvement of water management in air-breathing and air-blowing PEMFC at low temperature using hydrophilic silica nano-particles

This study examined the effect of the hydrophilicity of an anode catalyst layer on the performance of a proton exchange membrane fuel cell (PEMFC). Hydrophilic SiO2 particles were added to the anode catalyst layer in an attempt to improve the water management and performance in an air-blowing and air-breathing PEMFC operated at low temperature. The SiO2-doped membrane electrode assemblies (MEAs) were prepared using a spraying method and the contact angle was measured using the sessile drop method at room temperature. Each MEA was tested at 35∘C in an air-blowing and air-breathing PEMFC. Pure dry hydrogen as fuel was fed in the electrode using graphite plate with serpentine channels. Air, as the oxidant, was diffused in the electrode through an open window made from gold-plated stainless steel with 70% opening for the air-breathing PEMFC. In case of the air-blowing PEMFC, a graphite plate with serpentine channels was used for the cathode instead of an open window. The polarization curves, impedance spectra and fraction of water from the anode outlet were measured. The hydrophilic anode catalyst layer contributed to the hydration of the anode in the air-blowing system and water removal from the cathode in air-breathing system, respectively. For both the air-blowing and air-breathing systems, the performances of the cell were improved by 26.9% and 44.4%, respectively, using the 40 wt% SiO2-doped MEAs compared with the MEA without SiO2.