123rd General Meeting of the KCS

Type Poster Presentation
Area Material Chemistry
Room No. Exhibition Hall 2
Time 4월 19일 (금요일) 11:00~12:30
Code MAT.P-488
Subject Study of electronic structures and cation disorder behavior of lithium transition metal oxides (LMO, M = Co and Ni) with various lithium composition from first principles calculation
Authors Hyosik Kang, Sanghun Lee*
Nanochemistry, Gachon University Global Campus, Korea
Abstract Lithium ion battery (LIB) has been the most popular energy storage device for portable electronics due to its high energy and power density. Among many materials for the cathode, the layer-structured LiCoO2 has been most widely employed for LIB since its first commercialization by SONY. Thus, a lot of experimental as well as calculational investigations have been performed to characterize properties of LiCoO2 for decades. Meanwhile, to overcome several drawbacks of LiCoO2, such as, environmental risk and high cost, many efforts to replace Co with alternative transition metals, for eample, Ni, have been made. The main problem of LiNiO2 is the formation of nonstoichiometric lithium nickel oxide and the high level of “cation disorder” or “cation mixing” behavior of Li and Ni ions. In this work, the electronic structures of lithium transition metal oxides (LiCoO2, Li0.5CoO2, CoO2, LiNiO2, Li0.5NiO2, and NiO2) and the cation disorder in LixMO2 (x = 0.98, 0.92, 0.85) are investigated using the density functional theory (DFT) calculations. For a reasonable estimation of the band structure and the density of state (DOS) of LiCoO2, we managed to obtain Hubbard U for Co. The calculated electronic structures of fully lithiated systems are in good agreement with the previous studies and accord with predictions. However, in the cases of half-lithiated ones, the band structure and DOS are out of predictions, which, we believe, comes from its asymmetric geometry around oxygen atoms. In addition, the energy barrier for cation disorder in LiNiO2 is much lower than that in LiCoO2, which is consistent with the experimental observation.
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