Performance Characterization of Lithium-Ion Cells Possessing Carbon-Carbon Composite-Based Anodes Capable of Operating Over a Wide Temperature Range

NASA has interest in secondary energy storage batteries that display high specific energy, high energy density, long life characteristics, and perform well over a wide range of temperatures, in order to enable a number of future applications. Due to favorable performance attributes, lithium-ion technology has emerged as one of the most promising systems to meet these demanding performance requirements. Of these attributes, the ability to perform well over a wide range of temperatures (i.e., +40”C to 40°C) is, perhaps, the most challenging requirement to satisfy, especially at low temperatures. For this reason, at JPL we have focused our efforts on developing improved electrolyte formulations and demonstrating lithium-ion cells capable of operating over a wide range of temperatures. In this paper, we will present the results of the performance characterization of prototype lithium-ion cells that contain novel carbon-carbon composite anodes developed and fabricated by LiTech LLC. As part of the study, two different cell sizes were evaluated (4 Ah and 700 mAh) and the electrolyte type has also been varied with the intent of comparing the low temperature capabilities. The low temperature electrolytes studied include: 1.0 M LiPF6 in EC + EMC (1:2 v/v YO) [l], 1.4 M LiPFG in EC + EMC (1:3 v/v ‘3’0) [2] and an electrolyt