Performance characteristics of lithium-ion cells for NASA's Mars 2001 Lander application

NASA requires lightweight rechargeable batteries for future missions to Mar s and the outer planets that are capable of operating over a wide range of temperatures, with high specific energy and energy densities. Due to the at tractive performance characteristics, lithium-ion batteries have been ident ified as the battery chemistry of choice for a number of future application s, including Mars revers and landers. The Mars 2001 Lander (Mars Surveyor P rogram MSP 01) will be one of the first missions which will utilize lithium -ion technology. This application will require two lithium-ion batteries, e ach being 28 V (eight cells), 25 Ah and 8 kg. In addition to the requiremen t of being able to supply at least 200 cycles and 90 days of operation on t he surface of Mars, the battery must be capable of operation (both charge a nd discharge) at temperatures as low as -20 degrees C. To assess the viabil ity of lithium-ion cells for these applications, a number of performance ch aracterization tests have been performed, including: assessing the room tem perature cycle life, low temperature cycle life (-20 degrees C), rate capab ility as a function of temperature, pulse capability, self-discharge and st orage characteristics, as well as mission profile capability, This paper wi ll describe the Mars 2001 Lander mission battery requirements and will cont ain results of the cell testing conducted to-date in support of the mission .