Development of prototype sealed bipolar lithium/sulfide cells

Development of a prototype bipolar battery containing 13-cm dia cells for electric-vehicle propulsion is underway at Argonne National Laboratory (ANL). Both Li/FeS and Li/FeS{sub 2} cells have been tested with LiCl-LiBr-KBr electrolyte and MgO powder separators for electrolyte-starved cell operation at 400 to 425{degrees}C. These cells achieved the high performance and stability needed for the intended application. An innovative feature of this bipolar battery is a metal/ceramic bonded peripheral seal for each cell. The development of corrosion-resistant sealant materials at ANL has let to metal/ceramic bonds about 100 times stronger that obtainable with commercially available sealants for service at over 300{degrees}C. This peripheral seal promotes long battery life by eliminating electrolyte loss and prohibiting transport of electrolyte from one cell to the next in a bipolar stack. Fabrication facilities have been recently constructed that enable development of 13-cm I.D. peripheral seals. The initial tests of prototype bipolar Li/FeS and Li/FeS{sub 2} cells indicate improved performance as a result of scale-up. The 7-mm thick, 13-cm dia cells have total weight of 0.25 kg (cell density 2.8 g/cm{sup 3}). These cells are operated at 425{degrees}C. The Li/FeS{sub 2} cell exhibits 180 Wh/kg at a 30 Wh/kg discharge rate and the Li/FeS cell more » delivered 130 Wh/kg at a 25 W/kg rate. The low internal impedance of these cells enables high peak specific power capability; 400 W/kg for Li/FeS{sub 2} and 24 W/kg for Li/FeS at 80% DOD. 11 refs., 10 figs., 1 tab. « less