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1 Department of Energy Conversion and Storage, Technical University of Denmark 2 Proton conductors, Department of Energy Conversion and Storage, Technical University of Denmark 3 Energy and Materials, Department of Chemistry, Technical University of Denmark 4 Northeastern University 5 Northeastern University
High molecular weight polybenzimidazole (PBI) was synthesized and grafted with benzimidazole pendant groups. The high molecular weight of PBI resulted in good film-forming properties and superior tensile strength. With a phosphoric acid doping level (ADL) of 13.1, a tensile strength of 16 MPa was achieved at room temperature. Grafting of benzimidazole moieties onto the PBI macromolecular chain introduced additional basic sites which allowed the membrane to achieve higher phosphoric acid uptakes. A molar acid conductivity, defined as the specific conductivity of each mole of doping acid, was proposed to evaluate the effective conductivity contributed from the doping acids. With a grafting degree of 5.3% and an ADL of 13.1, the PBI membranes exhibited a total conductivity of 0.15 S cm-1. A H2-air fuel cell based on this membrane showed a peak power density of 378 mW cm-2 at 180 °C without humidification. © 2013 The Royal Society of Chemistry.
Polymer Chemistry, 2013, Vol 4, Issue 17, p. 4768-4775
Molecular weight; Phosphoric acid; Proton exchange membrane fuel cells (PEMFC); Semiconductor doping; Tensile strength; Grafting (chemical)
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