Sulfonated polysulfone ionomer membranes for fuel cells

Sulfonated polysulfone (SPSU) membranes with different sulfonation levels have been prepared and evaluated as proton exchange membranes in polymer electrolyte fuel cells (PEFC). The membranes have been characterized by ion-exchange capacity (IEC), thermal analysis, proton conductivity and single cell performance. The introduction of sulfonic groups in the base polymer produces an increase in glass transition temperature (T-g) from 190 to about 200-220 degreesC and a thermal decomposition of polymer at lower temperature. Proton conductivity of 4.3 x 10(-2) S . cm(-1) at 80 degreesC on a SPSU membrane with IEC = 1.25 meq/g was obtained. Membrane/electrodes assemblies (MEAs) prepared with SPSU gave, in single cell tests at 80 degreesC, power densities of 400 and 500 mW . cm(-2) in H-2/air and H-2/O-2, respectively.