FY08 Membrane Characterization Report for Hybrid Sulfur Electrolyzer

摘要

This report summarizes results from all of the membrane testing completed to date at the Savannah River National Laboratory (SRNL) for the sulfur dioxide-depolarized electrolyzer (SDE). Several types of commercially-available membranes have been analyzed for ionic resistance and sulfur dioxide transport including perfluorinated sulfonic acid (PFSA), sulfonated polyether-ketone-ketone (SPEKK), and polybenzimidazole membranes (PBI). Of these membrane types, the poly-benzimidazole membrane, Celtec-L, exhibited the best combination of characteristics for use in an SDE. Several experimental membranes have also been analyzed including hydrated sulfonated Diels-Alder polyphenylenes (SDAPP) membranes from Sandia National Laboratory, perfluorosulfonimide (PFSI) and sulfonated perfluorocyclobutyl aromatic ether (S-PFCB) prepared by Clemson University, hydrated platinum-treated PFSA prepared by Giner Electrochemical Systems (GES) and Pt-Nafion 115 composites prepared at SRNL. The chemical stability, SO2 transport and ionic conductivity characteristics have been measured for several commercially available and experimental proton-conducting membranes. Commercially available PFSA membranes such as the Nafion series exhibited excellent chemical stability and ionic conductivity in sulfur dioxide saturated sulfuric acid solutions. Sulfur dioxide transport in the Nafion membranes varied proportionally with the thickness and equivalent weight of the membrane.