This paper is a summation of past, present and future work with Li-Ion cells. Direct emphasis will be placed upon the development of cycle life and related components. Other discussion includes: cell design, operational temperature variations, rate capability and energy density. Accelerated performance will be characterized both in GEO and LEO “on-orbit” profiles. To support findings and authenticity of the test data being presented, details of the test configuration and test parameters will be covered as applicable. In addition, future endeavors will be discussed, encompassing expected performance improvements and developmental planning. The intent is to keep the satellite community abreast of recent developments at the cell level and to help direct sound decisions in power system design variations from the current Nickel-Hydrogen (NiH2) and Nickel-Cadmium (NiCd) technologies.