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Impact of trace extrinsic defect formation on the local symmetry transition in spinel LiNi0.5Mn1.5O4−δ systems and their electrochemical characteristics

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Abstract

Many fundamental studies have been conducted on the electrochemical and electronic structures in transition metal cation-substituted LiNi0.5Mn1.5O4 systems. These systems have potential use as 5 V-level high voltage cathode materials for lithium ion batteries, but there are only a few reports regarding the control of their symmetry transitions which contribute the electronic structures and Li+ transport efficiency. We address this solid chemistry and the corresponding electrochemical characteristics using both systematic experimental and theoretical approaches. Trace substitution of Cu2+ with Mn4+ (CuMn) can promote the symmetry transition from Fd[3 with combining macron]m to P4332 phase in oxygen-deficient LiNi0.5Mn1.5O4−δ. This behavior is detectable by Fourier-transform infrared and Raman spectroscopies but undetectable by X-ray diffraction, suggesting that the symmetry transition was localized in the space near the point of extrinsic defects CuMn in the spinel framework. Notably, a very small amount of Cu2+ substitution not only affects the local atomic arrangement but also remarkably affects the macroscopic electrochemical redox responsiveness, including the inactivation of Mn3+/Mn4+ redox couples, suppression of Mn ion dissolution, and enhancing the C rate capability (increasing the electron conductivity, and reducing the activation barrier for lithium ion hopping along the most energetically preferable 8a–16c–8a route) and cyclability.

Graphical abstract: Impact of trace extrinsic defect formation on the local symmetry transition in spinel LiNi0.5Mn1.5O4−δ systems and their electrochemical characteristics

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Publication details

The article was received on 12 Aug 2018, accepted on 19 Oct 2018 and first published on 22 Oct 2018


Article type: Paper
DOI: 10.1039/C8TA07825D
Citation: J. Mater. Chem. A, 2018, Advance Article
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    Impact of trace extrinsic defect formation on the local symmetry transition in spinel LiNi0.5Mn1.5O4−δ systems and their electrochemical characteristics

    H. Shiiba, N. Zettsu, S. Kida, D. Kim and K. Teshima, J. Mater. Chem. A, 2018, Advance Article , DOI: 10.1039/C8TA07825D

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