Characterization of LiNiO2 by XPS

We report x-ray photoemission spectra (XPS) of lithium nickel oxide (LiNiO2). XPS spectra were measured with the Physical Electronics Model 5400 x-ray photoelectron spectrometer using unmonochromatized Mg Kα x rays at two pass energy settings corresponding to analyzer energy resolutions of 1.34 and 0.54 eV. We present the survey spectrum (binding energy range of 0–1100 eV) measured at an analyzer energy resolution of 1.34 eV. Multiplexes of the Li, C, O, and Ni photoemission lines, valence band region, as well as Ni LVV Auger lines were measured at an analyzer energy resolution of 0.54 eV. Our results indicate that the near surface region is highly contaminated with Li2CO3 in agreement with earlier work which showed that even samples of LiNiO2 scraped in vacuum are highly contaminated with Li2CO3 but to a lesser degree. Despite the high degree of contamination, curve fitting analysis was successful in resolving the Li, Ni, and O contributions corresponding to LiNiO2.