This Phase I SBIR project seeks to develop a 500 Wh/kg Lithium primary battery for intended application as the primary power source on landers and probes for future missions to Titan/Enceladus and near Earth asteroids. The proposed battery technology aims to offer a viable alternative to Li/SO2 primary batteries which were used in the most recent mission to Titan. A thorough analysis of power requirements for the Huygens-Cassini mission (2005 landing) will be undertaken from the point of view of identifying engineering areas where the benefits of introduction of a more potent battery could be realized. Developers will focus on the engineering and performance testing of two distinctly different cell designs in a 32650 cylindrical cell housing. An integral part of the new battery will be a system of smart electrical heaters which, at a fraction of available battery power, will turn resistive heaters on and off as required to compensate for heat losses through the battery box wall (the assumption of the model being studied is that the battery should not require the use of external radioactive heating sources to maintain operation). This project will see the introduction of several new materials which will be manufactured by the contractor for purposes of boosting the energy efficiency of the proposed battery system.