Comparative study of the solid electrolyte interphase on graphite in full Li-ion battery cells using X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and electron microscopy

Commercial lithium-ion cells with LiMn1/3Ni1/3Co1/3O2 as the positive electrode, graphite as the negative electrode and a LiPF6-EC:PC:DEC electrolyte were cycled under several conditions, and the solid electrolyte interphase (SEI) on the graphite electrode was studied. Nuclear magnetic resonance (NMR) spectroscopy confirmed that LiPF6-EC:PC:DEC electrolyte was used in the cell and the relative volume ratio between solvents was acquired via quantitative NMR. Secondary ion mass spectrometry, X-ray photoelectron spectroscopy, and a dual-beam focused ion beam/scanning electron microscope have been used to characterize the thickness, morphology and chemical composition of complex SEI on graphite anodes. The advantages and limitations of the characterization techniques are discussed and the results compared to provide a more comprehensive analysis of the SEI.