1. Development of Nanocomposite Membranes for High Pressure PEM Fuel Cell/Electrolyzer Applications Michael Pien, Marvin Warshay, Steven Lis, Radha Jalan ElectroChem, Inc 400 W. Cummings Park Woburn, MA 01801 Christine Felice, Deyang Qu Dept of Chemistry, University of Massachusetts Boston, Boston, MA 01225 AIAA Denver, CO August 5, 2009

2. Advance in Polymer Nanocomposites US 2,531,396 1950 Elastomer Reinforced with a Modified Clay US 3,084,117 1963 Organoclay Polyolefin Compositions US 4,739,007 1988 Composite Material and Process for Manufacturing Clay-based Thin Film as Gas Barrier - Claist Perfluorinated Sulfonated Polymer as Proto Exchange Membrane - high temperature fuel cell - direct methanol fuel cell

3. Structure of Platelets for Barrier Gallery Height (exchangeable) Tetrahedral Octahedral Tetrahedral

4. Different Types of Composites Conventional Composite Intercalated Nanocomposite Exfoliated Nanocomposite

5. Polymeric Proton Conductive Membrane O2O2 H2 H2 e- H+ Proton Exchange Membrane (PEM) - perfluorinated sulfonate polymer 2 e - + 2 H+ H2OH2O 2 e - + 2 H+ V

6. Hydrogen Crossover Development of mixed potential Decrease current efficiency Different thermal and water management Hot spots

7. Objectives Develop Low H 2 Crossover proton conductive polymer membranes for High pressure and Low current density operating electrolyzers Retain high proton conductivity of the new membranes Investigate the morphology of the new membranes for the reduction of H 2 crossover

8. Selection of Platelets Swelling properties Capacity of host water and organic molecules High cation exchange capacities High aspect ratio Large surface area

9. H 2 Permeation Evaluation Electrochemical method Limiting current density H2H2 Reference electrode Working electrode Counter electrode V H2H2 N2N2 H 2 = 2 H + + 2 e -

10. Conductivity Evaluation In-the-plane conductivity - impedance - various humidity and temperature Through-the-plane conductivity - impedance

11. H 2 Permeation of the Nanocomposite Membranes

12. Initial Results of the New Nanocomposite membranes Membranewt% clayThickness 10 -3 in H 2 crossover mA/cm 2 Conductivity mS/cm Nafion 211010.92311.9 Nafion 115050.38511.1 Membrane A10%1.50.3858.9 Membrane B10%30.2318.8 Membrane C20%1.50.2695.8

13. Fuel Cell Evaluation Membrane D : hot-pressing a Membrane A (10% clay) between two Nafion 212 membranes Membrane F : hot-pressing a Membrane C (20% clay) between two Nafion 212 Membranes The thickness of membranes D and F is about 5 mils similar to the thickness of Nafion 115 membrane

16. Which Composite ? Conventional Composite Intercalated Nanocomposite Exfoliated Nanocomposite

17. Nanocomposite Membranes Optimization Selection of materials Design of Experiment  Pretreatment  Particle size  Loading  Mixing

19. Methods of Melt Process

20. Conclusions Polymer Nanocomposite based on platelets can reduce the hydrogen permeation Polymer nanocomposite membranes can keep good proton conductivity

21. Future work Optimize new polymer nanocomposites based on a Design of Experiment New polymer nanocomposites that allow durability characterization

22. Acknowledgement This work is funded by NASA under Contract NNX09CA92C

23. Electrolyzer Evaluation