Abstract: A method for making a sulfonated polymer electrolyte membrane for use in an electrochemical fuel cell is disclosed, the method comprising sulfonating a non-aromatic polymer membrane material, wherein the membrane material is not irradiated prior to sulfonation. A sulfonated polymer electrolyte membrane for use in an electrochemical fuel cell produced according to the foregoing method and an electrochemical fuel cell comprising such a sulfonated polymer electrolyte membrane are also disclosed.

Abstract: A water insoluble additive for improving the performance of an ion-exchange membrane, such as in the context of the high temperature operation of electrochemical fuel cells. The insoluble additive comprises a metal oxide cross-linked matrix having proton conducting groups covalently attached to the matrix through linkers. In one embodiment, the metal is silicon and the cross-linked matrix is a siloxane cross-linked matrix containing silicon atoms cross-linked by multiple disiloxy bonds and having proton conducting groups covalently attached to the silicon atoms through alkanediyl linkers.