Direct Experimental Probe of the Ni(II)/Ni(III)/Ni(IV) Redox Evolution in LiNi0.5Mn1.5O4 Electrodes

Ruimin Qiao, L. Andrew Wray, Jung Hyun Kim, Nicholas P W Pieczonka, Stephen J. Harris, Wanli Yang

    Research output: Contribution to journalArticle

    Abstract

    The LiNi0.5Mn1.5O4 spinel is an appealing cathode material for next generation rechargeable Li-ion batteries due to its high operating voltage of ∼4.7 V (vs Li/Li+). Although it is widely believed that the full range of electrochemical cycling involves the redox of Ni(II)/(IV), it has not been experimentally clarified whether Ni(III) exists as the intermediate state or a double-electron transfer takes place. Here, combined with theoretical calculations, we show unambiguous spectroscopic evidence of the Ni(III) state when the LiNi0.5Mn1.5O4 electrode is half charged. This provides a direct verification of single-electron-transfer reactions in LiNi0.5Mn1.5O4 upon cycling, namely, from Ni(II) to Ni(III), then to Ni(IV). Additionally, by virtue of its surface sensitivity, soft X-ray absorption spectroscopy also reveals the electrochemically inactive Ni2+ and Mn2+ phases on the electrode surface. Our work provides the long-awaited clarification of the single-electron transfer mechanism in LiNi0.5Mn1.5O4 electrodes. Furthermore, the experimental results serve as a benchmark for further spectroscopic characterizations of Ni-based battery electrodes.

    Original languageEnglish (US)
    Pages (from-to)27228-27233
    Number of pages6
    JournalJournal of Physical Chemistry C
    Volume119
    Issue number49
    DOIs
    StatePublished - Dec 10 2015

    Fingerprint

    electron transfer
    Electrodes
    electrodes
    probes
    electric batteries
    Electrons
    cycles
    X ray absorption spectroscopy
    spinel
    absorption spectroscopy
    Cathodes
    cathodes
    Oxidation-Reduction
    Electric potential
    electric potential
    ions
    x rays
    spinell
    Lithium-ion batteries

    ASJC Scopus subject areas

    • Physical and Theoretical Chemistry
    • Electronic, Optical and Magnetic Materials
    • Surfaces, Coatings and Films
    • Energy(all)

    Cite this

    Qiao, R., Wray, L. A., Kim, J. H., Pieczonka, N. P. W., Harris, S. J., & Yang, W. (2015). Direct Experimental Probe of the Ni(II)/Ni(III)/Ni(IV) Redox Evolution in LiNi0.5Mn1.5O4 Electrodes. Journal of Physical Chemistry C, 119(49), 27228-27233. https://doi.org/10.1021/acs.jpcc.5b07479

    Direct Experimental Probe of the Ni(II)/Ni(III)/Ni(IV) Redox Evolution in LiNi0.5Mn1.5O4 Electrodes. / Qiao, Ruimin; Wray, L. Andrew; Kim, Jung Hyun; Pieczonka, Nicholas P W; Harris, Stephen J.; Yang, Wanli.

    In: Journal of Physical Chemistry C, Vol. 119, No. 49, 10.12.2015, p. 27228-27233.

    Research output: Contribution to journalArticle

    Qiao, Ruimin ; Wray, L. Andrew ; Kim, Jung Hyun ; Pieczonka, Nicholas P W ; Harris, Stephen J. ; Yang, Wanli. / Direct Experimental Probe of the Ni(II)/Ni(III)/Ni(IV) Redox Evolution in LiNi0.5Mn1.5O4 Electrodes. In: Journal of Physical Chemistry C. 2015 ; Vol. 119, No. 49. pp. 27228-27233.
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    abstract = "The LiNi0.5Mn1.5O4 spinel is an appealing cathode material for next generation rechargeable Li-ion batteries due to its high operating voltage of ∼4.7 V (vs Li/Li+). Although it is widely believed that the full range of electrochemical cycling involves the redox of Ni(II)/(IV), it has not been experimentally clarified whether Ni(III) exists as the intermediate state or a double-electron transfer takes place. Here, combined with theoretical calculations, we show unambiguous spectroscopic evidence of the Ni(III) state when the LiNi0.5Mn1.5O4 electrode is half charged. This provides a direct verification of single-electron-transfer reactions in LiNi0.5Mn1.5O4 upon cycling, namely, from Ni(II) to Ni(III), then to Ni(IV). Additionally, by virtue of its surface sensitivity, soft X-ray absorption spectroscopy also reveals the electrochemically inactive Ni2+ and Mn2+ phases on the electrode surface. Our work provides the long-awaited clarification of the single-electron transfer mechanism in LiNi0.5Mn1.5O4 electrodes. Furthermore, the experimental results serve as a benchmark for further spectroscopic characterizations of Ni-based battery electrodes.",
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