Loker Hydrocarbon Research Institute, Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States.
J Phys Chem B. 2011 Dec 15;115(49):14462-8. doi: 10.1021/jp206774c. Epub 2011 Nov 14.
Anhydrous electrolytes with high proton conductivity and adequate chemical stability in the temperature range of 120-180 °C can be very useful in electrochemical devices such as fuel cells, sensors, and electrolyzers. Developing such proton-conducting materials has been challenging. We have fabricated and characterized the performance of such membranes, based on poly-2-vinylpyridinium dihydrogenphosphate (P2VP-DHP), that can operate in the range of 105-180 °C under anhydrous conditions. The ionic conductivity of the membrane was 0.01 S cm(-1) at 140 °C. Proton conduction occurs by ionization of the quaternary ammonium group and by Grotthus-type transport that involves the rapid rotation of the dihydrogenphosphate anion. The activation energy for proton transport was 50 kJ/mol. The transport number of the proton was measured by impedance spectroscopy and potential-step techniques. The measured value was in the range of 0.17-0.20. A membrane-and-electrode assembly using the P2VP-DHP was tested as an electrochemical hydrogen pump. This demonstration shows the advantage of membranes based on a polymer amine salt in electrochemical applications that require operating under water-free conditions. Weight loss measurements at 120 °C in air confirmed the thermal and oxidative stability of the membrane. The properties of the P2VP-DHP membrane reported here provide the basis for further development of proton-conducting polymer electrolyte membranes for operating temperatures above 100 °C in anhydrous environments.
在 120-180°C 的温度范围内具有高质子电导率和足够化学稳定性的无水电解质在电化学装置（如燃料电池、传感器和电解槽）中非常有用。开发这种质子传导材料一直具有挑战性。我们已经制造并表征了基于聚-2-乙烯基吡啶二氢磷酸盐（P2VP-DHP）的此类膜的性能，该膜可以在 105-180°C 的无水条件下运行。在 140°C 时，膜的离子电导率为 0.01 S cm(-1)。质子传导是通过季铵基团的电离和涉及二氢磷酸盐阴离子快速旋转的 Grotthus 型传输来实现的。质子传输的活化能为 50 kJ/mol。质子迁移数通过阻抗谱和电位跃变技术测量。测量值在 0.17-0.20 范围内。使用 P2VP-DHP 的膜-电极组件被测试为电化学氢气泵。该演示表明，在需要在无水条件下运行的电化学应用中，基于聚合物胺盐的膜具有优势。在空气中于 120°C 进行的重量损失测量证实了膜的热和氧化稳定性。这里报道的 P2VP-DHP 膜的性能为进一步开发在无水环境中工作温度高于 100°C 的质子传导聚合物电解质膜提供了基础。
