Lithium-ion cell technology demonstration for future NASA applications

Abstract

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 their attractive performance characteristics, lithium-ion (Li-ion) batteries have been identified as the battery chemistry of choice for a number of future applications, including planetary orbiters, rovers and landers. For example, under the Mars Surveyor Program M5P 01 lithium-ion batteries were developed by Lithion (each being 28 V, 25 Ah, 8-cells, and 9 kg) and fully qualified prior to mission cancellation. In addition to the requirement of being able to supply at least 90 cycles on the surface of Mars, the battery demonstrated operational capability (both charge and discharge) over a large temperature range (-20/spl deg/C to +40/spl deg/C), with tolerance to nonoperational excursions to -30/spl deg/C and 50/spl deg/C. Currently, JPL is implementing lithium-ion technology on the 2003 Mars Exploration Rover (MER), which will be coupled with a solar array. This mission has similar performance requirements to that of the 2001 Lander in that high energy density and a wide operating temperature range are necessitated. In addition to planetary rover and lander applications, we are also engaged in determining the viability of using lithium-ion technology for orbiter applications that require exceptionally long life (/spl deg/20,000 cycles at partial depth of discharge). To assess the viability of lithium-ion cells for these applications, a number of performance characterization tests have been performed (at the cell and battery level) on state-of-art prototype lithium-ion cells, including: assessing the cycle life performance (at varying DODs), life characteristics at extreme temperatures ( +40/spl deg/C), rate capability as a function of temperature (-30/spl deg/C to 40/spl deg/C), pulse capability, self-discharge and storage characteristics, as well as, mission profile capability. This paper will describe the current and future NASA missions that are considering lithium (Li) ion batteries and will contain results of the cell testing conducted to-date to validate the technology for these missions.