Inorganic–Polymer Composite Membranes for Proton Exchange Membrane Fuel Cells

Composite membranes consisting primarily of a polymer and an inorganic proton conducting particle or a proton conducting polymer containing inorganic particles for use as proton exchange membranes in low and intermediate temperature fuel cells are reviewed. The chemistry of major inorganic additives that have been used is described in terms of their structure and intrinsic ability to conduct protons. Composites are classified in terms of four main classes: inorganic proton conductors suspended in inert polymers; inorganic particles added to extend polymeric ionomers; inorganic proton conductors blended with polymeric ionomers; and polymer acid complexes between basic polymers and acidic inorganic particles.

Keywords:

• proton conductor
• ionomer
• pefluorosulfonic acid polymer
• silica
• zirconia
• heteropoly acid

Acknowledgements

The author would like to thank Dr. Fanqin Meng and Ms. Dana Lipfert for collating the references used in this review and all of his co‐workers that have been involved in our study of heteropoly acid proton composites and conduction, especially Dr. Steven F. Dec, Dr. Steven J. Hamrock, and Dr. John A. Turner. NREL, the US DOE, 3M, and the Xcel Energy Renewable Energy Fund are thanked for financial support.