Charge–Discharge Mechanism of High-Entropy Co-Free Spinel Oxide Toward Li+ Storage Examined Using Operando Quick-Scanning X-Ray Absorption Spectroscopy

Xu Feng Luo, Jagabandhu Patra, Wei Tsung Chuang, Thi Xuyen Nguyen, Jyh Ming Ting, Ju Li, Chih Wen Pao, Jeng Kuei Chang

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1 Citation (Scopus)

Abstract

Transition metal high-entropy oxides (HEOs) are an attractive class of anode materials for high-performance lithium-ion batteries (LIBs). However, owing to the multiple electroactive centers of HEOs, the Li+ storage mechanism is complex and debated in the literature. In this work, operando quick-scanning X-ray absorption spectroscopy (XAS) is used to study the lithiation/delithiation mechanism of the Cobalt-free spinel (CrMnFeNiCu)3O4 HEO. A monochromator oscillation frequency of 2 Hz is used and 240 spectra are integrated to achieve a 2 min time resolution. High-photon-flux synchrotron radiation is employed to increase the XAS sensitivity. The results indicate that the Cu2+ and Ni2+ cations are reduced to their metallic states during lithiation but their oxidation reactions are less favorable compared to the other elements upon delithiation. The Mn2+/3+ and Fe2+/3+ cations undergo two-step conversion reactions to form metallic phases, with MnO and FeO as the intermediate species, respectively. During delithiation, the oxidation of Mn occurs prior to that of Fe. The Cr3+ cations are reduced to CrO and then Cr0 during lithiation. A relatively large overpotential is required to activate the Cr reoxidation reaction. The Cr3+ cations are found after delithiation. These results can guide the material design of HEOs for improving LIB performance.

Original languageEnglish
Article number2201219
JournalAdvanced Science
Volume9
Issue number21
DOIs
Publication statusPublished - 2022 Jul 25

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Chemical Engineering(all)
  • Materials Science(all)
  • Biochemistry, Genetics and Molecular Biology (miscellaneous)
  • Engineering(all)
  • Physics and Astronomy(all)

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