Data for "High-voltage operation reveals surface reconstruction as primary contributor to impedance growth over CEI evolution in Ni-Rich layered oxides"

Abstract

This dataset contains the raw data for electrochemical impedance spectroscopy (EIS), cycling , X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM). More information regarding the data structure and the data file types is given in the "README" file. The data was used to plot all scientific figures published in the following manuscript:

Title: "High-voltage operation reveals surface reconstruction as primary contributor to impedance growth over CEI evolution in Ni-Rich layered oxides" DOI: https://doi.org/10.1016/j.ensm.2026.105115

Abstract of the publication: "Enhancing the energy density of lithium-ion batteries by increasing the nickel content in layered oxides as cathode materials is hindered by accelerated degradation at high potentials. Here, we resolve the degradation mechanism of single-crystalline LiNi0.83Co0.11Mn0.06O2 (NCM) by comparing different aging protocols, varying upper cutoff voltage, time exposed to high potential (4.5 V versus Li+/Li) and number of cycles. The impedance growth due to these stressors is quantified by electrochemical analysis, including potentiostatic electrochemical impedance spectroscopy (PEIS). The structural and chemical degradation is investigated post mortem via transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS). The analysis reveals that the organic components of the CEI are oxidized and removed during extended holds at 4.5 V. However, this CEI thinning occurs alongside an increase in charge transfer resistance RCT. Furthermore, cells undergoing cycling versus hold protocols exhibited similar CEI compositions despite different RCT. Therefore, we conclude that the CEI plays a minor role in the observed impedance increase. In contrast, the formation of a rock-salt-type SRL correlates with kinetic limitations and capacity fade. These findings provide a basis for distinguishing the effects of CEI evolution from surface reconstruction during long-term, high-voltage operation."