1.5 Ah pouch cells based on Li(Ni0.5Mn0.3Co0.2)O2 cathodes and graphite anodes, both containing poly (vinylidene fluoride) (PVDF) binders, were systematically overcharged to 100, 120, 140, 160, 180, and 250% state of charge (SOC), at which point they vented. The cells were subsequently discharged to 0% SOC and disassembled under an inert atmosphere for characterization. A combination of X-ray photoelectron spectroscopy (XPS), scanning-electron microscopy (SEM), energy-dispersive spectroscopy (EDS), 6Li SSNMR, and X-ray diffraction (XRD) analysis of the NMC532 cathodes indicates the formation of a thin C- and O-rich cathode electrolyte interphase layer, progressive Li loss above 140% SOC, and retention of the bulk crystal structure at all states of charge.
Bareño, J., Dietz Rago, N., Dogan, F., Graczyk, D. G., Tsai, Y., Naik, S. R., … Bloom, I. (2018). Effect of overcharge on Li(Ni0.5Mn0.3Co0.2)O2/graphite lithium ion cells with poly(vinylidene fluoride) binder. III — Chemical changes in the cathode. Journal of Power Sources, 385, 165–171. https://doi.org/10.1016/j.jpowsour.2017.12.061