本實驗使用自行合成的聚(2,5-苯並咪唑) (Poly(2,5-benzimidazole), ABPBI)高分子，摻雜磷酸與氯化銻/氯化錫/氯化鐵，形成有機/無機複合膜，希望能將此ABPBI複合膜作為質子交換膜，應用於操作溫度為160~200℃的PEMFC。研究中分為兩個部份來探討ABPBI複合膜的性質: (1)其在不同溫度下(80~240℃)之質子導電率; (2)藉由拉伸試驗來比較複合膜之機械性質。
在未增濕氣氛下(PH2O~0.03 atm)，摻雜磷酸與氯化銻的複合膜在160℃時，具有最高質子導電率為6.7×10-2 S/cm; 其次為摻雜磷酸與氯化錫的複合膜，在200℃下可達到最高質子導電率4.5×10-2 S/cm，而摻雜磷酸與氯化鐵的複合膜在180℃下可達最高質子導電率3.5×10-2 S/cm。三種ABPBI複合膜之質子導電率皆比僅摻雜磷酸的ABPBI膜還要高了許多，其最高質子導電率為在180℃下的2.0×10-2 S/cm。
研究中透過拉伸試驗來比較膜材之機械性質，其中未摻雜磷酸與氯化物的ABPBI膜之楊氏係數為3.67±0.61 GPa，強度高但可塑性低，屬於脆性材料; 摻雜磷酸之後，膜材可塑性增加，強度下降，其楊氏係數為0.16±0.04 GPa，屬於延性材料。相較之下，摻雜磷酸與氯化錫/氯化鐵的複合膜也屬於延性材料，其楊氏係數分別為0.17±0.03 GPa與0.065±0.017 GPa，而摻雜磷酸與氯化銻的複合膜則介於延性材料與脆性材料之間，其楊氏係數為0.22±0.01 GPa。

In the attempt of membrane electrolyte for high-temperature proton
exchange membrane fuel cell, we have synthesized Poly(2,5-
benzimidazole), the so-called ABPBI. A few organic/inorganic membranes
are prepared through doped with phosphoric acid (PA) and one of antimony,
tin, or iron chlorides. And their proton conductivities are measured between
80 and 240 C, their mechanical properties are measured in tensil testing.
Under the unhumdified conditions, with partial pressure of water vapor =0.03 atm, the composite membrane, doped with PA and SbCl5, exhibits the highest conductivities, measured 6.7×10-2 S cm-1 at 160 C. In contrast, the composite membrane, doped with PA and SnCl4, shows the proton conductivity 4.5×10-2 S cm-1 at 200 C. The composite membrane, doped with PA and FeCl3, displays the proton conductivity 3.5×10-2 S cm-1 at 180 C. The highest conductivities of these three membranes are higher than that the membrane doped with PA alone, which shows the highest conductivity 2.0×10-2 S cm-1 at 180 C. SbCl5 appears to be the best co-dopant with PA for ABPBI, just like in case of PBI.
Intriguingly, the three composite membranes demonstrate their unique mechanical properties. Consistent with the literature knowledge on PBI membrane, the undoped ABPBI membrane displays brittle characteristics with Young modulus 3.67±0.61 GPa, while the PA doped ABPBI shows plasticity and a smaller Young modulus 0.16±0.04 GPa. The composite membranes of PA and SnCl4 or FeCl3 also show ductile properties, with Young modulus 0.17±0.03 GPa and 0.065±0.017 GPa. The composite membrane of PA and SbCl5 shows brittle characteristics at small strains, but ductile features at large strains. Its Young modulus is measured 0.22±0.01 GPa.

1. Li, Q., et al., Approaches and recent development of polymer electrolyte membranes for fuel cells operating above 100 C. Chemistry of materials, 2003. 15(26): p. 4896-4915.
2. Das, P.K., X. Li, and Z.-S. Liu, Analysis of liquid water transport in cathode catalyst layer of PEM fuel cells. International Journal of Hydrogen Energy, 2010. 35(6): p. 2403-2416.
3. Acres, G., et al., Electrocatalysts for fuel cells. Catalysis Today, 1997. 38(4): p. 393-400.
4. Garche, J., et al., Encyclopedia of electrochemical power sources. 2013: Newnes.
5. Ticianelli, E., et al., Methods to advance technology of proton exchange membrane fuel cells. Journal of the Electrochemical Society, 1988. 135(9): p. 2209-2214.
6. Wilson, M.S., J.A. Valerio, and S. Gottesfeld, Low platinum loading electrodes for polymer electrolyte fuel cells fabricated using thermoplastic ionomers. Electrochimica Acta, 1995. 40(3): p. 355-363.
7. Li, Q., et al., The CO poisoning effect in PEMFCs operational at temperatures up to 200 C. Journal of the Electrochemical Society, 2003. 150(12): p. A1599-A1605.
8. Smith, A.L., The analytical chemistry of silicones. Vol. 160. 1991: Wiley-Interscience.
9. Kreuer, K., Solid Proton Conducting Electrolytes: Conduction Mechanism, Phenomenology and New Materials for Fuel Cell Applications. Max-Planck-Institute for Solid State Research, 2005.
10. Heo, P., et al., Sn0. 9In0. 1P2O7-based organic/inorganic composite membranes application to intermediate-temperature fuel cells. Journal of The Electrochemical Society, 2007. 154(1): p. B63-B67.
11. Cassidy, P.E., Thermally stable polymers, synthesis and properties. 1980.
12. Imai, Y., K. Uno, and Y. Iwakura, Polybenzazoles. Die Makromolekulare Chemie, 1965. 83(1): p. 179-187.
13. Ma, Y.-L., et al., Conductivity of PBI membranes for high-temperature polymer electrolyte fuel cells. Journal of The Electrochemical Society, 2004. 151(1): p. A8-A16.
14. Wainright, J. and M. Litt, RF Savinell in Handbook of Fuel Cell, Fundamentals, Technology, and Applications, Vol. 3. 2003, John Wiley & Sons, New York.
15. Kim, H.J., et al., Synthesis of Poly (2, 5‐benzimidazole) for Use as a Fuel‐Cell Membrane. Macromolecular rapid communications, 2004. 25(8): p. 894-897.
16. Kim, S.-K., et al., Cross-linked poly (2, 5-benzimidazole) consisting of wholly aromatic groups for high-temperature PEM fuel cell applications. Journal of membrane science, 2011. 373(1): p. 80-88.
17. Zheng, H., L. Petrik, and M. Mathe, Preparation and characterisation of porous poly (2, 5benzimidazole)(ABPBI) membranes using surfactants as templates for polymer electrolyte membrane fuel cells. international journal of hydrogen energy, 2010. 35(8): p. 3745-3750.
18. Asensio, J.A. and P. Gómez‐Romero, Recent Developments on Proton Conduc‐ting Poly (2, 5‐benzimidazole)(ABPBI) Membranes for High Temperature Poly‐mer Electrolyte Membrane Fuel Cells. Fuel Cells, 2005. 5(3): p. 336-343.
19. Asensio, J.A., S. Borrós, and P. Gómez-Romero, Polymer electrolyte fuel cells based on phosphoric acid-impregnated poly (2, 5-benzimidazole) membranes. Journal of the Electrochemical Society, 2004. 151(2): p. A304-A310.
20. Phair, J. and S. Badwal, Materials for separation membranes in hydrogen and oxygen production and future power generation. Science and technology of advanced materials, 2006. 7(8): p. 792-805.
21. Kim, Y.S., et al., Fabrication and characterization of heteropolyacid (H 3 PW 12 O 40)/directly polymerized sulfonated poly (arylene ether sulfone) copolymer composite membranes for higher temperature fuel cell applications. Journal of Membrane Science, 2003. 212(1): p. 263-282.
22. Miura, N. and N. Yamazoe, Development of new chemical sensors based on low-temperature proton conductors. Solid State Ionics, 1992. 53: p. 975-982.
23. Ponomareva, V., E. Shutova, and A. Matvienko, Conductivity of proton electrolytes based on cesium hydrogen sulfate phosphate. Inorganic materials, 2004. 40(7): p. 721-728.
24. Taninouchi, Y.-k., et al., Dehydration behavior of the superprotonic conductor CsH 2 PO 4 at moderate temperatures: 230 to 260° C. Journal of Materials Chemistry, 2007. 17(30): p. 3182-3189.
25. Matsui, T., et al., Effect of pyrophosphates as supporting matrices on proton conductivity for NH 4 PO 3 composites at intermediate temperatures. Journal of Power Sources, 2007. 171(2): p. 483-488.
26. Sun, C. and U. Stimming, Synthesis and characterization of NH 4 PO 3 based composite with superior proton conductivity for intermediate temperature fuel cells. Electrochimica Acta, 2008. 53(22): p. 6417-6422.
27. Muroyama, H., et al., Electrochemical properties of MH 2 PO 4/SiP 2 O 7-based electrolytes (M= alkaline metal) for use in intermediate-temperature fuel cells. Solid State Ionics, 2007. 178(27): p. 1512-1516.
28. Nagao, M., et al., Proton conduction in In3+-doped SnP2O7 at intermediate temperatures. Journal of The Electrochemical Society, 2006. 153(8): p. A1604-A1609.
29. Jin, Y., et al., An H 3 PO 4-doped polybenzimidazole/Sn 0.95 Al 0.05 P 2 O 7 composite membrane for high-temperature proton exchange membrane fuel cells. Journal of Power Sources, 2011. 196(15): p. 6042-6047.
30. Kim, T.H., et al., Proton‐Conducting Zirconium Pyrophosphate/Poly (2, 5‐benzimidazole) Composite Membranes Prepared by a PPA Direct Casting Method. Macromolecular Chemistry and Physics, 2007. 208(21): p. 2293-2302.
31. Zheng, H. and M. Mathe, Enhanced conductivity and stability of composite membranes based on poly (2, 5-benzimidazole) and zirconium oxide nanoparticles for fuel cells. Journal of Power Sources, 2011. 196(3): p. 894-898.
32. Rho, Y.W., S. Srinivasan, and Y.T. Kho, Mass transport phenomena in proton exchange membrane fuel cells using o 2/he, o 2/ar, and o 2/n 2 mixtures ii. Theoretical analysis. Journal of the Electrochemical Society, 1994. 141(8): p. 2089-2096.
33. Ramberg, W. and W.R. Osgood, Description of stress-strain curves by three parameters. 1943.