3. New polymer electrolytes

Polymer electrolyte membranes with high ionic conductivity are one of key components in PEFCs (polymer electrolyte fuel cells). Perfluorinated sulfonic acid polymer electrolytes such as Nafion are mostly investigated as the best candidate so far, but due to the cost performance non-fluorinated polymer membranes are also studied as possible candidates. The problem of such membranes is chemical stability, especially durability against radical species. The study shows, however, that even for hydrocarbon membranes careful microscopic design of polymer network makes it possible to realize high ionic conductivity, high mechanical strength and high chemical stability.*

TFCL, with the background of R&D in non-perfluorinated high ionic conductivity membranes, is now developingnew ionomer solutions that are inevitable for ensuring good interface contacts between the catalyst layer and polymer electrolyte membranes. The curent technology relies on perfluorinated ionomer solutions such as Nafion solution, but non-perfluorinated ionomer will give a strong impact as this will be suitable for use in new hydrocarbon-type membranes.

Along with this, composite membranes based on various kinds of membranes are of strong interest for realizing new functions in the fuel cell system.

With the experience of the investigations on mechanisms of ion and water transport in membrane for fuel cells,** TFCL will serve to the fuel cell industry by developing new composite membranes and propsing new system design for fuel cells.

*: J. Qiao and T. Okada: "Hydrocarbon Polymer Electrolytes for Fuel Cell Applications", in "Electroanalytical Chemistry Research Developments", Chap. 2, pp. 85-134 (Ed. by P. N. Jiang), Nova Science Publishers, Inc., New York (2007).

**: T. Okada, M. Saito, and K. Hayamizu: "Ion Exchange and Transport Characteristics of Perfluorinated Polymer Electrolyte Membranes for Fuel Cells" in "Electroanalytical Chemistry Research Developments", Chap. 1, pp. 7-84 (Ed. by P. N. Jiang), Nova Science Publishers, Inc., New York (2007).