sPSU/PEI and Functionalized ZrP-SH Compose Material as High Temperature Proton Conducting Membrane

• Main Authors: Chuang Hsieh, Chi-Hsun, 莊謝奇勳
• Other Authors: Po-Jen Chu
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/d6tt3w

碩士 === 國立中央大學 === 化學學系 === 107 === Proton exchange membrane fuel cells operating at high temperatures can avoid the problems of carbon monoxide poisoning catalysts, increase the chemical reaction rate of batteries, etc. However, current commercial PEMFC membranes are prepared based on polyperfluorosulfonic acid materials, for example, the Nafion series of DuPont. But at high temperatures, water molecules tend to evaporate from the Nafion membrane, causing severe deterioration in ionic conductivity that does not provide satisfactory performance. Phosphoric acid-doped polybenzimidazole (PBI) is a common choice for polymer electrolyte membranes at high temperatures because PBI has good phosphoric acid doping ability can exhibit high proton conductivity at high temperatures. However, in very high phosphoric acid, the PBI membrane will decrease the mechanical properties. In addition, the high price of PBI also causes obstacles to widespread use. The development of high-temperature fuel cell membranes with high proton conductivity and high chemical stability without loss of mechanical integrity has become a material science research issue to be overcome. In this study, it is shown that the PEI can form a relatively complete crosslinked structure with sPSU with the increase of the proportion of addition. Therefore, the composite polymer film not only exhibits better thermal stability but also can effectively improve the phosphoric acid doping of the membrane. In addition to retention ability, these membranes can maintain conductivity at high temperatures. Among these membranes, a membrane with 40 wt% PEI has the best high-temperature proton conductivity, 1.2*10-1 S/cm at 160 °C. Incresing PEI content to 50 wt% PEI decreased its proton conductivity by 9*10-2 S/cm. Furthermore, addition of ZrP-SH causes the structure of the membrane to become denser due to the interaction between the coupling agent (MPTMS) and the polymer, so that the phosphoric acid doped amount is decreases, which in turn affects the proton conductivity of the membrane, but when the amount of ZrP-SH added >5wt%, the proton conductivity will increase slightly. This is because ZrP has the ability to proton transfer, which can be effectively improved by functionalization. In the absence of phosphoric acid, ZrP-SH can establish a new proton transfer channel with the polymer to improve its performance.