Polyarylenethioethersulfone Membranes for Fuel Cells (Postprint)
Abstract
High performance, sulfonated polyarylenethioethersulfone (SPTES) polymers have been developed as membranes for fuel cells. These high molecular weight polymers synthesized by a polycondensation process have an aromatic backbone along with high sulfonic acid content that provides for their high conductivity and robust mechanical properties. Bulky phenyl-based end-capping agents are incorporated into the system to maintain high water stability and retain high proton conductivity. Films with good mechanical properties were obtained by solvent casting. SPTES polymer systems with a 50% degree of sulfonation (SPTES-50) exhibited high proton conductivity (>100 mS/cm) at 65 ?C and 85%RH. Membrane electrode assemblies (MEAs) fabricated using SPTES-50 electrolytes that incorporate conventional electrode application techniques have shown high proton mobility. Electrochemical evaluation was performed using nonlinear regression analysis to obtain Tafel parameters. The electrochemical performance of SPTES-50 was comparable to Nafion?. Electrochemical impedance spectra were analyzed in terms of a pore diffusion model. Catalyst utilization for SPTES MEAs using conventional electrode inks with perfluorinated binders was similar to that exhibited by Nafion?. Estimates of hydrogen fuel permeability based upon measured open circuit voltage indicate that SPTES-50 MEAs exhibit a slightly higher rate of fuel crossover compared to Nafion?. Thermogravimetric analysis shows good thermal stability. The high temperature stability (up to 250 ?C) and high intrinsic proton conductivities of SPTES-50 qualifies it to be a potential candidate for membranes in fuel cells.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2007
- Accession Number
- ADA473512
Entities
People
- Stanley J. Rodrigues
- Thomas L. Reitz
Organizations
- Air Force Research Laboratory