Research On Transport Characteristic In PEMFC Cathode And The Performance Optimization

Polymer electrolyte membrane fuel cells (PEMFC) are important alternative choice for energy converting in the future. Because of their environmental benefits and relative high power density, the PEM fuel cells are a prime candidate for vehicle and other mobile applications of all sizes. Water management is a key issue for fuel cell operation:lack of water in the membrane would lower the efficiency of protein transport from the anode to cathode side, while too much liquid water in the cathode side would cause flood, which means too much reaction area on the catalyst is covered by liquid water.3-D numerical models of PEMFC were build to investigate the transport characteristics in the cathode side. Straight and interdigitated gas flow channel PEMFC were build. The distribution of water in the cathode gas channels and gas diffusion layers were obtained at different anode humidification and varies porous materials.Results showed that the proper humidification in the anode side could improve the PEMFC performance, but overload of water in the anode side may also inhibit the back diffusion of water from the cathode to the anode side thus cause flooding in the cathode. The hydrophobicity of the structure affects water transportation in the fuel cell significantly. Hydrophobic materials could lower the rate of water saturation in the flow field to prevent the water flooding in the cathode side.When magnetic force was induced to the cathode gas diffusion layer, oxidation reaction was enhanced. Meanwhile, amount of liquid water on the cathode catalyst surface was reduced as a result of the Kelvin force.â… -â…¤curve also showed that the current density increased significantly.