This work applies in situ Auger electron spectroscopy and X-ray photoelectron spectroscopy to the study of surface redox on LiNi1/3Mn1/3Co1/3O2 during charging and overcharging. We observe that all three transition metals are surface redox active, and that oxygen oxidation occurs for voltages above ≈4.2 V O2 loss above ≈4.7 V, mediated by carbon redox, leads to partial reduction of the transition metals at the surface during overcharging.
Tang, C. Y., Feng, L., Haasch, R. T., & Dillon, S. J. (2018). Surface redox on Li[Ni1/3Mn1/3Co1/3]O2 characterized by in situ X-ray photoelectron spectroscopy and in situ Auger electron spectroscopy. Electrochimica Acta, 277, 197–204. https://doi.org/10.1016/j.electacta.2018.04.199