Synthesis of layered cathode material Li[CoxMn1−x]O2 from layered double hydroxides precursors |
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Authors: | Yanluo Lu Lan Yang |
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Institution: | a State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China b Beijing Key Laboratory, Beijing Institute of Clothing Technology, Beijing 100029, PR China |
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Abstract: | Cathode materials LiCoxMn1−x]O2 for lithium secondary batteries have been prepared by a new route—precursor method of layered double hydroxides (LDHs). In situ high-temperature X-ray diffraction (HT-XRD) and thermogravimetric analysis coupled with mass spectrometry (TG-MS) were used to monitor the structural transformation during the reaction of CoMn LDHs and LiOH·H2O: firstly the layered structure of LDHs transformed to an intermediate phase with spinel structure; then the distortion of the structure occurred with the intercalation of Li+ into the lattice, resulting in the formation of layered LiCoxMn1−x]O2 with α-NaFeO2 structure. Extended X-ray absorption fine structure (EXAFS) data showed that the Co-O bonding length and the coordination number of Co were close to those of Mn in LiCoxMn1−x]O2, which indicates that the local environments of the transitional metals are rather similar. X-ray photoelectron spectroscopy (XPS) was used to measure the oxidation state of Co and Mn. The influences of Co/Mn ratio on both the structure and electrochemical property of LiCoxMn1−x]O2 have been investigated by XRD and electrochemical tests. It has been found that the products synthesized by the precursor method demonstrated a rather stable cycling behavior, with a reversible capacity of 122.5 mAh g−1 for the layered material LiCo0.80Mn0.20]O2. |
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Keywords: | Layered Li[CoxMn1&minus x]O2 LDHs Precursor method Cathode materials In situ HT-XRD |
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