Design and Testing of the Mars Exploration Rover Lithium Ion Batteries

In a collaborative effort, Lithion and NASA/JPL developed a lithium ion battery capable of meeting the physical and electrochemical requirements for the 2003/2004 Mars Exploration Rover (MER) missions. The cells provide up to 145 Wh/kg, while the specific energy at the battery level, including wiring harnesses, thermal hardware and mounting hardware is approximately 90 Wh/kg. This paper discusses the specific requirements of the mission and how those requirements were met. Furthermore, an overview of the technique used to select cells for batteries is presented. The cell selection criteria resulted in cell to cell variation of approximately ± 0.6% in the first qualification unit.