Li(B) ingot preparation scale-up study. Final report. [Anodes for thermal batteries]

Results of the investigation to determine the feasibility of scaling the lithium-boron alloy preparation from laboratory to commercial scale are reported. Earlier reports have demonstrated the usefulness of this alloy for anodes in thermal batteries which operate at temperatures well above th melting point of lithium. Electrochemically, the alloy behaves very much like lithium, attaining a potential only 20 mV below lithium when discharged in a LiCl-KCl eutectic melt. Its discharge characteristics under heavy loads suggest that the anode behaves as if the active species were molten, yet the anode remains a solid at operating temperatures. Single cells employing this anode were developed and described earlier. A single cell consists of three components, an anode, a separator layer and a catholyte layer. The anode is made up of foil as thin as 0.003 inch spotwelded on a 0.005-inch thick stainless steel collector. The separator layer is an electrolyte-MgO mixture. Its purpose is to prevent direct contact and therefore reaction between the anode and the active cathode material. Many separator configurations were investigated earlier; our final choice has now been adopted for all thermal batteries employing lithium compound anodes. The catholyte layer is a mechanical mixture of FeS/sub 2/ and electrolytemore » powder. Both the separator and the catholyte are pressed powder pellets. Alloy preparation and physical properties are reported, and test results are detailed. (WHK)« less