Charge–Discharge Mechanism of High‐Entropy Co‐Free Spinel Oxide Toward Li + Storage Examined Using Operando Quick‐Scanning X‐Ray Absorption Spectroscopy
Author(s)Luo, Xu-Feng; Patra, Jagabandhu; Chuang, Wei-Tsung; Nguyen, Thi Xuyen; Ting, Jyh-Ming; Li, Ju; Pao, Chih-Wen; Chang, Jeng-Kuei; ... Show more Show less
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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)3 O4 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.
DepartmentMassachusetts Institute of Technology. Department of Nuclear Science and Engineering
Luo, Xu-Feng, Patra, Jagabandhu, Chuang, Wei-Tsung, Nguyen, Thi Xuyen, Ting, Jyh-Ming et al. 2022. "Charge–Discharge Mechanism of High‐Entropy Co‐Free Spinel Oxide Toward Li + Storage Examined Using Operando Quick‐Scanning X‐Ray Absorption Spectroscopy." Advanced Science, 9 (21).
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