1 research outputs found
Sulfonated poly(2,5-benzimidazole) (SABPBI) impregnated with phosphoric acid as proton conducting membranes for polymer electrolyte fuel cells
Previously cast ABPBI membranes were sulfonated by doping with sulfuric acid followed by heat treatment at 450 .C for 5 min in air.
Sulfonation degrees between 35 and 49% of the benzimidazole rings were achieved. The resulting SABPBI membranes were impregnated
with phosphoric acid (H3PO4 85%/H2O, 70:30 bath). For concentrated phosphoric acid baths (above 65%), the capacity of these membranes
for phosphoric acid uptake (and consequently also their conductivity) increased with the degree of sulfonation. Sulfonated and acid doped
SABPBI membranes were characterized in terms of degree of sulfonation, thermal stability (TGA), X-ray diffraction, FTIR spectroscopy
and proton conductivity in the dry state, and compared with phosphoric acid impregnated ABPBI studied earlier. The maximum conductivity
measured in dry conditions was 3.5 ~ 10.2 S cm.2 at 185 .C for SABPBI E4.6H3PO4 (with a degree of sulfonation of 41%) which compares
favorably with non-sulfonated ABPBI and makes feasible their application in PEM Fuel Cells working at temperatures of 150.200 .C.
c 2004 Elsevier Ltd. All rights reserved.This work was carried out within the framework of
the “Xarxa Temà tica de Piles de Combustible” of the
Generalitat de Catalunya and the “Red de Pilas de Combustible
del CSIC” and was partially funded by MCyT
(Spain) (MAT2002-04529-C03). We thank the MCyT for a
pre-doctoral fellowship awarded to J.A.A.Peer reviewe