MEMBRANES CONSISTING OF POLYAZOLES, METHOD FOR THEIR PRODUCTION AND FUEL CELLS USING SUCH MEMBRANES

摘要

The membranes according to the invention can be obtained from polyazoles having an inherent viscosity of greater than 1.1 dl/g by means of a method having the following steps: a) preparation of a solution of the polyazoles in organic solvents, b) shaping the obtained solution to form a membrane shape, c) heating of the solution which has been brought into the membrane shape to a temperature in the range of from 50 to 90°C until a self-supporting membrane has been formed, and d) tempering the membrane obtained from step c) at increasing temperatures in the range of from 120 to 500°C until the content of solvents in the membrane is less than 5% by weight. The membranes according to the invention can be used in high-temperature fuel cells. They have increased mechanical stability and, after doping with phosphoric acid, have a high degree of long-term stability at the operating temperatures of the high-temperature fuel cells up to 250°C.