Electrode structure analysis and surface characterization for lithium-ion cells simulated low-Earth-orbit satellite operation: II: Electrode surface characterization

Abstract

As a sequence work to investigate the performance-degradation mechanism of an aged commercial laminated lithium-ion cell experiencing 4350-cycle charge–discharge in a simulated low-Earth-orbit (LEO) satellite operation, we performed the surface characterization of LiCoO 2 cathode and graphite anode by Fourier transform infrared-Attenuated total reflection (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) analysis in this work. Overall, the graphite anode had a larger change in surface chemistry than that of the LiCoO 2 cathode. Except the common surface components, we detected Co metal at the aged graphite surface in the first time. This Co metal deposition was believed to originate from Co 2+ dissolution from LiCoO 2 cathode during prolonged cycling, and detrimental to structure stability of LiCoO 2 cathode which was a main cause of cell capacity loss. The amount of surface-film component was also estimated by FTIR analysis. Though the total amount of surface film increased, the organic (inorganic) surface film decreased (increased) with prolonged cycling.