Performance characteristics of Yardney lithium-ion cells for the Mars 2001 Lander application

NASA requires lightweight rechargeable batteries for future missions to Mars 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 attractive performance characteristics, lithium-ion batteries have been identified as the battery chemistry of choice for a number of future applications, including Mars Rovers and Landers. The Mars 2001 Lander (Mars Surveyor Program MSP 01) will be among one of the first missions which will utilize lithium-ion technology. This application will require two lithium-ion batteries, each being 28 V (eight cells), 25 Ah and 9 kg (18 kg total). In addition to the requirement of being able to supply at least 90 cycles on the surface of Mars after a 1 year storage and cruise time, the battery must be capable of operation (both charge and discharge) over a wide temperature range (-20°C to +40°C), with tolerance to nonoperational excursions to -30°C and 50°C. To assess the viability of lithium-ion cells for these applications, a number of performance characterization tests have been performed on state-of-art Yardney lithium-ion cells, including: assessing the room temperature cycle life, low temperature cycle life (20°C), rate capability as a function of temperature (-30° to 40°C), pulse capability, self-discharge and storage characteristics, as well as, mission profile capability. This paper describes the Mars 2001 Lander mission battery requirements and presents results of the cell testing conducted to-date in support of the mission