Surface Changes in Commercial Li-Ion Cells after Life Cycle Testing for Satellites

Li-ion cells were cycled as part of a program to assess commercial technologies for space applications. Cells showing capacity loss were disassembled and compared with new cells using scanning electron microscopy (SEM) x-ray diffraction (XRD), and time-of-flight secondary ion mass spectrometry (TOF-SIMS) to determine the underlying cause for the capacity loss. Results indicate a loss of lithium from the cathode and a thicker, non-active, fluorine-rich layer on the surface of the anode.