The current research on polymer electrolytes for fuel cells is focused on the optimization of a membrane working at 120 °C and low humidity levels (<30%), which are the real operative conditions in the case of automotive applications. Among a wide variety of tested polymer systems, polybenzimidazole (PBI)-based membranes, doped with phosphoric acid, are considered the best alternative to Nafion, owing to their high conductivity even with no or low humidification and promising electrochemical performances. At present, these membranes suffer a relevant drawback: leaching of the free acid during fuel cell operation, which impedes their use below at least 150 °C. In this article, an experimental strategy for improving the acid retention capability of the membrane is presented. Therefore, new polymeric architectures, based on PBI, are synthesized with an increased number of basic sites, differently interspaced along the polymer backbone. Subsequently, composite membranes are prepared by dispersing in the previously prepared matrices micro- and nanosized silica, functionalized with basic structures
Mustarelli, P., Quartarone, E., Magistris, A. (2009). Fuel Cells - Proton-Exchange Membrane Fuel Cells | Membranes: Polybenzimidazole. In Jurgen Garche, Chris K. Dyer, Patrick T. Moseley, Zempachi Ogumi, David A. J. Rand, Bruno Scrosati (a cura di), Encyclopedia of Electrochemical Power Sources (pp. 734-740). NLD : Elsevier Science [10.1016/B978-044452745-5.00933-3].
Fuel Cells - Proton-Exchange Membrane Fuel Cells | Membranes: Polybenzimidazole
Mustarelli, P;
2009
Abstract
The current research on polymer electrolytes for fuel cells is focused on the optimization of a membrane working at 120 °C and low humidity levels (<30%), which are the real operative conditions in the case of automotive applications. Among a wide variety of tested polymer systems, polybenzimidazole (PBI)-based membranes, doped with phosphoric acid, are considered the best alternative to Nafion, owing to their high conductivity even with no or low humidification and promising electrochemical performances. At present, these membranes suffer a relevant drawback: leaching of the free acid during fuel cell operation, which impedes their use below at least 150 °C. In this article, an experimental strategy for improving the acid retention capability of the membrane is presented. Therefore, new polymeric architectures, based on PBI, are synthesized with an increased number of basic sites, differently interspaced along the polymer backbone. Subsequently, composite membranes are prepared by dispersing in the previously prepared matrices micro- and nanosized silica, functionalized with basic structures
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