Preparation And Studies On Micro-porous Layer With Hydrophilic/Hydrophobic Composite Pores Structure

Characteristics of micro-porous layer (MPL) are very important for performances of proton exchange membrane fuel cell (PEMFC). The hydrophobic PTFE and capillarity in MPL provide steady channels for water and gas, and electric carbon blacks provide channels for electron. The author analysed hydrophilic/hydrophobic pores theory and wetting property between water and hydrophilic/hydrophobic pores, then demonstrated it. The MPL with hydrophilic/hydrophobic composite pores had been prepared and also analysed. Conclusions had been summarized as following:(1) XC-72 carbon black had been treated with nitric acid solution. The first, change treated time under the same concentration, the second, change the concentration under the same time.(2) XPS tests indicate that C=O surface group had increased after treated in nitric acid and oxygen contents of carbon atom had also increased from 11.9% to 33.0%, which increased hydrophilic property of carbon black. From BET experiment results, specific surface area and pore volume had been increased for the treated carbon black.(3) Through traditional preparation method, the MPL with treated carbon black had been prepared. Based on numeration of hydrophilic porosity, the proportion of hydrophilic pores in the new MPL were more than traditional MPL.(4) Through analysing the water exsiting in porous medium, studying the water removal and membrane maintenance humidifying in running of PEMFC, it indicates that water removal has great relation to the hydrophilic/hydrophobic and the pore-size distribution of GDL, and find the MPL with composite pores can achieve self-humidifying of PEMFC.(5) The novel MEA prepared by the treated carbon black can run in basic stability under no external humidifying equipment.