Chemical Synthesis and Properties of Spinel Li1−xCo2O4−δ |
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Authors: | S ChoiA Manthiram |
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Institution: | Materials Science and Engineering Program, ETC 9.104, The University of Texas at Austin, Austin, Texas, 78712 |
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Abstract: | Spinel Li1−xCo2O4−δ samples with 0.44≤(1−x)≤1 have been synthesized by chemically extracting lithium with the oxidizer NO2BF4 in acetonitrile medium from the LT-LiCoO2 synthesized at 400°C. Rietveld analysis of the X-ray diffraction data reveals that the Li1−xCo2O4−δ samples adopt the normal cubic spinel structure with a cation distribution of (Li1−x)8aCo2]16dO4−δ. Redox iodometric titration data indicate that the LT-LiCoO2 tends to lose oxygen on extracting lithium and the spinel Li1−xCo2O4−δ samples are oxygen-deficient. Both infrared spectroscopic and magnetic susceptibility data suggest that the LiCo2O4−δ spinel is metallic with itinerant electrons. The tendency to lose oxygen on extracting lithium from the LT-LiCoO2 and the observed metallic behavior of the spinel LiCo2O4−δ are explained on the basis of a qualitative band diagram. |
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