The use of lithium-ion batteries for JPL's Mars missions

On the surface of Mars, there are currently two operational rovers that utilize robust Li-ion batteries that have contributed to their demonstrated long life, which exceeded the original mission objective. In early 2004, NASA-JPL successfully landed two Rovers on Mars (i.e., Spirit and Opportunity), one of which is still operational and has completed over 4900 sols of operation (or over 13 years of operation). In August 2012, NASA-JPL's Mars Science Laboratory (MSL) Curiosity Rover landed on Mars, and has currently completed over 1500 Sols of operation and has driven > 14.5 km. The Li-ion battery chemistry developed for these missions, and established as the “heritage”, consists of meso-carbon microbeads (MCMB) anodes, LiNixCo1-xO2 (NCO) cathodes, and a low temperature ternary carbonate-based electrolyte developed at JPL. For future missions requiring high specific energy and the ability to operate over a wider temperature range, such as the Mars InSight mission, the next generation chemistry, consisting of graphite anodes, LiNiCoAlO2 (NCA) cathodes and a new low temperature electrolyte, is more attractive and has been demonstrated to provide improved performance, especially at very low temperatures. In order to demonstrate the capability of these technologies to meet mission requirements, as well as generate necessary data to aid in mission planning, a number of performance verification tests were performed on large capacity “proto-flight” prismatic EaglePicher-Yardney Division Li-ion cells, including Mars mission surface operation simulation testing. As described, these cells have been demonstrated to have excellent life characteristics and the ability to operate over a wide temperature range, with both charging and discharging at very low temperatures.