A solid polymer electrolyte membrane having a first surface and a second surface opposite the first surface, where the solid polymer electrolyte membrane has a failure force greater than about 115 grams and comprises a composite membrane consisting essentially of (a) at least one expanded PTFE membrane...http://www.google.com/patents/US20100086675?utm_source=gb-gplus-sharePatent US20100086675 - Solid Polymer Electrolyte and Process for Making Same
