Synthesis and properties of poly(aryl ether benzimidazole) copolymers for high-temperature fuel cell membranes

Acid doped polybenzimidazoles containing 4-phenyl phthalazinone moieties for high-temperature PEMFC

“…So O-H stretching at about 3600 cm À 1 and N-H stretching of imidazole ring at about 3400-3200 cm À 1 are expected. The benzimidazole characteristic bands can be clearly observed at 1630 cm À 1 (C ¼N/ C¼C stretching), 1605 cm À 1 (ring vibration of conjugation between benzene and imdazole rings), 1435 cm À 1 (in-plane ring vibration of 2,6-disubstituted benzimidazole), 1287 cm À 1 (imidazole ring breathing mode) and 806 cm À 1 (the heterocylic-ring vibration), similar with that reported previously [9,27]. Additionally, the strong absorption bands at 1230 cm À 1 and 1663 cm À 1 are ascribed to the -O-stretching and lactam of phthalazinone moiety, respectively, and they become more intense gradually with the increasing of 4-phenyl phthalazinone moiety content in the polymer backbone.…”

“…High temperature fuel cells operating at temperatures higher than 100 1C can provide many benefits, such as high CO tolerance, fast electrochemical reaction kinetics, and high fuel impurity tolerance, which allow for simplification of the fuel processing system and possible integration of the fuel cell stack with fuel processing unit [1,[9][10][11][12]. From the proton conducting mechanism points of view, phosphorus and phosphoric acid are amphoteric, with both proton donor (acidic) and proton acceptor (basic) groups to form dynamic hydrogen bond networks, in which protons can readily transfer by hydrogen bond breaking and forming processes [13,14].…”

“…However, the application of p-PBI in PEMFC is limited by its extremely poor processibility, as p-PBI is only soluble in strong acids. Much effort has been exercised to improve the solubility of p-PBI, such as incorporation of aryl ether linkage or m-phenylene linkage into p-PBI backbone [9,18]. However, these reports still compromise the thermal stability or the mechanical stability of p-PBI.…”

Intermediate temperature proton‐conducting membrane electrolytes for fuel cells

“…Some functional groups were introduced into PBIs to reduce the intermolecular forces between the polymer chains and to overcome the restricted polymer solubility as well as to improve other physicochemical properties of acid‐loaded PBI electrolytes. Such groups include, ether sulfone, fluorine, N‐phenyl 1,2,4‐triazole group, and perfluorocyclobutyl . In addition, the thermal stability, oxidation resistance, and water absorption were increased.…”

Preparation of Polybenzimidazole-Based Membranes and Their Potential Applications in the Fuel Cell System

“…Thus, we attempted to control the flexibility of the PBI material by employing dicarboxydiphenyl ether (DCDPE) (typically isophthalic acid (IPA) for PBI synthesis). The resulting poly(oxyphenylene benzimidazole) (OPBI) possesses an oxygen in the PBI backbone that can increase the flexibility of the film [21]. Subsequently, the OPBI membrane is further sulfonated by sulfuric acid and/or cross-linked by phosphoric acid to improve the proton conductivity and maintain a good stability at high operating temperatures, which could surpass the limitations of current proton conductive membranes.…”