Evaluation of lithium ion cells for space applications

Lithium ion batteries can provide a significant weight advantage over existing spacecraft energy storage systems. First generation, space capable, lithium ion batteries are expected to be one half the weight of the typical nickel-hydrogen batteries presently used for most present day spacecraft applications. Mature lithium ion batteries may be one third the weight of present day batteries. Accordingly it is important to understand how lithium ion cells will perform in operating scenarios typical of space applications. This paper describes a program designed to evaluate appropriate, available lithium ion cells in test regimes providing parametric characterization and life cycle data. The objective of this effort is to generate a data and experience base describing the ability of these cells to perform in typical space missions. The initial program task was the development of a dedicated test facility designed to accommodate the lithium ion cell's operating and safety-related characteristics. The facility provides individual cell control for all functions. Charge/discharge profiles, data acquisition, and safety features are managed by a dedicated computer. Initial cell testing was performed with Sanyo UR 18650 cells. Test regimes include 100% DOD and characterization cycling, as well as evaluation of performance in simulated GEO and LEO mission scenarios.