Proton conductivity of phosphoric acid doped polybenzimidazole and its composites with inorganic protontic conductors

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearch

Abstract

Polymer electrolytes have received considerable attention, especially for polymer electrolyte membrane fuel cells (PEMFCs) operating at temperatures above 100°C. phosphoric acid doped polybenzimidazole (PBI) and PBI composite membranes have been prepared in the present work. The PBI composites contain inorganic protonic conductors including zirconium phosphate (ZrP), (Zr(HPO4)2. nH2O); phosphotungstic acid (PWA), (H3PW12O40. nH2O); and silicotungstic acid (SiWA), (H4SiW12O40 . nH2O). The conductivity of phosphoric acid doped PBI and PBI composite membranes was found to be dependent on the acid doping level, relative humidity (RH) and temperature. A conductivity of 6.8 × 10-2 S cm-1 was observed for PBI membranes with a H3PO4 doping level of 5.6 (mole number of H3PO4 per repeat unit of PBI) at 200°C and 5% RH. A higher conductivity of 9.6 × 10-2 S cm-1 was obtained by blending 15 wt.% of ZrP in a PBI membrane at the same conditions. Homogeneous membranes with good mechanical strength were prepared by introducing PWA (20 - 30 wt.%) and SiWA (20 - 30 wt.%) into PBI, and their conductivity were found to be higher than or comparable with that of the PBI membrane up to 110°C.
Original languageEnglish
Title of host publicationProceedings of the 2nd European PEFC Forum
Number of pages848
Volumevolume 1
Place of PublicationSwitzerland
PublisherEuropean Fuel Cell Forum
Publication date2003
Edition1
Pages59-68
ISBN (Print)3-905592-13-4
Publication statusPublished - 2003
Event2nd European PEFC Forum - Lucerne, Switzerland
Duration: 30 Jun 20034 Jul 2003

Conference

Conference2nd European PEFC Forum
CountrySwitzerland
CityLucerne
Period30/06/200304/07/2003

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