Ion‐Containing Polymers as Semisolid Electrolytes in WO 3 ‐ Based Electrochromic Devices

Abstract

The water sorption, bound water, ionic conductivity, and chemical stability of polystyrene sulfonic acid (PSSA), polyethylenesulfonic acid (PESA), poly-2-acrylamido-2-methylpropanesulfonic acid (poly-AMPS), and perfluorosulfonic acid (Nafion) have been determined. All the ion-containing polymers investigated were found to contain 6 molecules of bound (nonfreezing) water per equivalent. The ionic conductivity generally increases with increasing water content up to about 6H2O/equivalent, then levels off. WO3 was stable in contact with the ion-containing polymers containing less than 6H2O/equivalent. A trade-off has to be made between W03 stability at high temperature and ion-containing polymer conductivity. Nafion and poly-AMPS were found to be chemically and electrochemically stable under the present experimental conditions. A good contact between the solid electrode and the semisolid electrolyte was best realized with a water soluble polymer. Best results have been obtained to date with poly-AMPS. © 1982, The Electrochemical Society, Inc. All rights reserved.