Degradation mechanism of LiNi0.82Co0.15Al 0.03O2 positive electrodes of a lithium-ion battery by a long-term cycling test

Tetsutaro Hayashi, Jiro Okada, Eiji Toda, Ryuichi Kuzuo, Nobumitsu Oshimura, Naoaki Kuwata, Junichi Kawamura

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    28 Citations (Scopus)

    Abstract

    We conducted a long-term cycling test of a commercial 18650-type lithium-ion battery with a capacity of 3100 mA. h at room temperature and investigated the degradation mechanism of the battery's LiNi 0.82Co0.15Al0.03O2 positive electrode. Sphericalaberration- corrected scanning transmission electron microscopy (Cs-STEM) revealed the presence of a thick degraded surface layer on the surface of the positive active material after the cycling test, and electron energy loss spectroscopy (EELS) revealed that the degraded surface layer continuously evolved from a LiNiO2 layered structure to a NiO structure, in the direction from the bulk toward the surface. Hard X-ray photoemission spectroscopy (HX-PES) indicated that the majority of low-valence Ni existed on the surface of the positive active material, which was charged after the cycling test, and that the degraded surface layer was inactive against charge reaction. The results suggest that the degraded surface layer was responsible for battery degradation during the cycling test. X-ray photoemission spectroscopy (XPS) indicated that Li2CO3 increased on the surface of the positive electrode after the cycling test. The phenomena would contribute to the formation of the degraded surface layer on the surface of the positive active material.

    Original languageEnglish
    Pages (from-to)A1007-A1011
    JournalJournal of the Electrochemical Society
    Volume161
    Issue number6
    DOIs
    Publication statusPublished - 2014

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Renewable Energy, Sustainability and the Environment
    • Surfaces, Coatings and Films
    • Electrochemistry
    • Materials Chemistry

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