Evaluation of Life Cycle Performance of Lithium Ion Cells for Space Applications 2006-01-3024
This paper describes a program at Boeing Phantom Works designed to evaluate life cycle performance of Lithium -Ion (Li-Ion) cells. The objective was to gather data, which will give us the capability to assess the performance of these cells during typical space missions.
Lithium-Ion (Li-Ion) cells can provide higher performance for spacecraft energy storage applications. Li-Ion cells have: (1) reduced mass, (2) increased volumetric efficiency, (3) improved cycle and calendar life, (4) higher power and energy (5) lower self discharge, (6) no “memory effect”, (7) excellent low temperature performance and (8) are more environmentally friendly than other types of batteries, such as Ag-Zn or NiH2 and; therefore, may be a better alternative to these traditional types of cells for space applications.
Life cycle testing was performed with Li-Ion cells purchased from three different cell manufacturers. Eight space cells have been subjected to a 25% depth of discharge (DoD) low earth orbit (LEO) cycle, which consists of 110 minutes per cycle equaling 13 cycles per day. The two Vendor A (45Ah) cells have undergone tests for more than seven years. The two Vendor B (42Ah) cells have undergone tests for more than four years, and two Vendor C (45Ah) cells have also been tested for more than two years, yielding an experience base ranging from approximately range 9,000 to 26,000 cycles. Data analyzed from testing consists of variation with cycle number of the following parameters: End of Cell Discharge Voltage, Recharge Ratio, Capacity, and Temperature.
Results from this effort enable a prediction of cell voltage performance, failure modes, and life cycle. These are all critical factors in the development of long-life cell systems for space travel applications.
