| Summary: | 碩士 === 國立臺灣科技大學 === 材料科學與工程系 === 104 === Recently, there has been great interest in developing polybenzimidazole (PBI) membranes for high temperature Proton Exchange Membrane Fuel Cell (PEMFC). Research on PBI membranes for high-temp PEMFC has encounter many problems, such as high solubility of PBI, Pt poisoning and low proton conductivity. Herein, we prepared pata-polybenzimidazole membranes (p-PBI) by sol-gel method and compared it with commercially available meta-polybenzimidazole membrane (m-PBI) which was prepared by solution casting method. p-PBI with an acid doping level(ADL) of 10 PA/RU showed proton conductivity of 0.208 S cm-1 which is twice higher than that of commercial m-PBI with the same acid doping level (0.11 S cm-1). Their properties were found to be dependent on their polymer structure as well as the membrane morphology. Microstructures of PBI membranes have been studied by AFM, conductive AFM, EDS and TEM. p-PBI prepared by sol-gel method with ADL=10 PA/RU showed well connected ion channel with size about 70 nm which is larger than that of commercial m-PBI (50 nm). In the fuel cell test, p-PBI membrane prepared by sol-gel method with an acid doping level(ADL) of 10 PA/RU showed peak power density of 1050 mW cm-2, which is twice higher than that of solution casting m-PBI membrane with the same acid doping level (570 mW cm-2). This indicates that, in addition to ADL, microstructure of membranes plays a very important role on the proton conductivity and fuel cell performance. Their morphological images observed by AFM, C-AFM and TEM show the existence of ionic channels, which can be good indication for proton conductivity of the membranes.
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