| Summary: | 碩士 === 元智大學 === 化學工程學系 === 93 === In this study, polybenzimidazole (PBI) and polybenzimidazole sulfonic acid (PBI-BS) were synthesized. The PBI membranes prepared for evaluation. PBI and PBI-BS were identified by element analysis, 1H-NMR, 13C-NMR, and FTIR spectroscopy. The membranes were prepared by casting the varied LiCl/PBI solution on a stainless steel cell in 2 wt% (Method I) or on a glass plate in 8 wt% (Method II) using spacer to control the thickness.
From the observation of SEM, the surfaces of the membranes prepared by Method II are smoother than those prepared by Method I. Results show acid doping level and proton conductivities of acid doped PBI membranes prepared by Method II are higher than those prepared by Method I. Proton conductivities of PPII-7.2 and PPII-10.8 are even higher than those of Nafion 117. MEA was prepared by membrane of PPII-7.2 for PEMFC test. The Pt loading were 1 mg/cm2 and 0.5 mg/cm2 at cathode, anode, respectively. At 200 ml/min of oxygen, 200 ml/min of hydrogen, and 70℃, the maximum power density of 100 mW/cm2 and the open circuit potential（OCV）of 0.83 V were obtained.
In conclusion, the conditions which are suitable for the preparation of PBI membranes are：
（1）The molar ratios of LiCl and PBI should be less than 10.8,
（2）The Method II is better for the membranes preparation.
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