Impact of P-Doped in Spinel LiNi0.5Mn1.5O4 on Degree of Disorder, Grain Morphology, and Electrochemical Performance

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• 作者：Yu-Feng Deng ; Shi-Xi Zhao ; Ya-Hui Xu ; Kai Gao ; Ce-Wen Nan
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：November 24, 2015
• 年：2015
• 卷：27
• 期：22
• 页码：7734-7742
• 全文大小：655K
• ISSN：1520-5002

文摘

LiNi_0.5-xP_2xMn_1.5-xO₄ (x = 0, 0.005, 0.01, and 0.02) submicrograins in regular octahedral shape with merely {111} surface facets and truncated octahedral shape with both {111} and {100} surface planes were obtained by the solid-state reaction method. The effect of doping P on ions arrangement, grain morphology, and the electrochemical performance of lithium nickel manganese oxide was investigated. The characterizations of X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), and selected area electron diffraction (SAED) confirm more Mn³⁺ ions in the structure to enhance the cationic disorder degree of LiNi_0.5Mn_1.5O₄ after P-doping. Comparing the LiNi_0.5Mn_1.5O₄ and LiNi_0.495P_0.01Mn_1.495O₄ samples both with regular octahedral morpology, their electrochemical performance could be remarkably improved by more disordered transition metal ions arrangement leading to higher conductivity of Li-ions and electrons. However, when the amount of P-doping further increased, the rate and cycle ability of the LiNi_0.480P_0.04Mn_1.480O₄ sample in truncated octahedral shape worsen dramatically even with a higher degree of cationic disorder. This could be on account of the crystal planes starting to dominate the electrochemical performance instead of ions arrangement under high voltage and large rate: the {111} facet is more favorable to the lithium ion transport than the {100} crystal plane for LiNi_0.5Mn_1.5O₄ submicrograins during charge and discharge.