Highly Oxygen Permeable Perfluoro Membrane for the Air Cathode of Lithium-Air Batteries

This proposal addresses development of highly oxygen permeable perfluoromembranes for Lithium-Air organic electrolyte batteries. These batteries have demonstrated very high specific capacity (greater than 500 Wh/kg) at low rates in pure oxygen. Oxygen from the air can be utilized if a membrane is developed that allows for oxygen transport but prevents solvents in the organic electrolyte from diffusion out into cell or attacking the membrane. Compact Membrane Systems, Inc. (CMS) membranes are high flux, defect-free nonporous membranes with very good separation characteristics for passing small molecules such as oxygen while retaining large molecules such as organic based solvents. CMS perfluoromembranes have excellent chemical and thermal resistance and are not plasticized by organic solvents. Data on CMS perfluoro membranes indicate that oxygen/solvent permeability ratios of 850 to 2620 are feasible, well in excess of program target of 200. Program focus will be on providing high oxygen permeability while minimizing loss of the electrolyte material. Liquid-side mass transfer is important to maximize total oxygen transport. The CMS membranes are commercial in several related applications so the probability of technical success is high. The developed oxygen-selective perfluoromembrane is expected to have significant military and commercial applications.