Rechargeable Lithium-Sulfur Battery with Non-Porous Ceramic Separator

Feasibility of a rechargeable lithium battery with sulfur cathode will be demonstrated. Air Force needs high specific energy, low cost rechargeable batteries for solar energy storage. Low cathode utilization and cycle fade have prevented Li-S batteries from reaching their potential. Cathode utilization can be improved dramatically using apolar and polar solvents in combination. Typically porous separators are used for lithium batteries, allowing constituents to migrate, resulting in cycle fade. To prevent inter-electrode constituent migration and capacity fading over charging cycles, a non-porous lithium ion conductive ceramic membrane will be utilized. The membrane developed recently at Ceramatec has conductivity of 1 mS/cm at 25C and 0.6 mS/cm at -20C. The membrane can be as thin as 10’s of microns with a laminated porous layer serving as mechanical support. The non-porous separator will prevent dendritic shorting, improving anode safety along with the use of an unreducible lithium salt. Specific energy theoretically is 2600 Wh/kg with a metallic lithium anode or 630 Wh/kg with a lithium carbon anode. Practical batteries would be >1000 or 250 Wh/kg with the two respective anodes. In Phase 1, several factors will be examined to determine their impact on capacity at different charge and discharge rates including a 0.5C rate, the highest rate anticipated for discharging.