NASA's Ocean Worlds exploration missions require batteries which operate as low as -100 C (defined here are "Ultra-Low Temperatures") and lower, a critically difficult challenge using current state-of-art materials. Conventional lithium primary batteries utilize a liquid catholyte with a low melting point which allows operation as low as -80 C. However, these conventional materials will be unable to push the low-temperature operation limit to meet NASA's requirements for Ocean Worlds missions.South 8 Technologies proposes the use of "Liquefied Gas Catholytes for Ultra-Low Temperature Lithium Primary Batteries". These catholytes are gaseous under standard conditions, but may be liquefied under mild pressures, showing exceptionally low melting points, very low viscosities and relatively high dielectric constants, allowing for ultra-low temperature operation of Lithium Primary Batteries. South 8 Technologies believes the technology proposed will enable energy storage at temperatures as low as -140 C, whereas the state-of-art allows operation is limited to -80 C. High temperature operation will be similar with operation limited to about +60 C. Further, the energy density of the active cathode material may be increased by as much as 30%, as will be shown. Voltage delay, a reoccurring issue in lithium primary batteries, may be reduced as well. These items will be discussed throughout the proposal.