Synthesis, phase stability, and electrochemically driven transformations in the LiCuO2-Li2CuO2 system

Prakash, A. S. ; Larcher, D. ; Morcrette, M. ; Hegde, M. S. ; Leriche, J. -B. ; Masquelier, C. (2005) Synthesis, phase stability, and electrochemically driven transformations in the LiCuO2-Li2CuO2 system Chemistry of Materials, 17 (17). pp. 4406-4415. ISSN 0897-4756

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Official URL: http://pubs.acs.org/doi/abs/10.1021/cm0508266

Related URL: http://dx.doi.org/10.1021/cm0508266

Abstract

Trivalent LiCuO2 was prepared by oxidative leaching of divalent Li2CuO2 in Br2-acetonitrile solutions at ambient temperature. Both phases were found to be thermally air unstable and the onset temperatures (100-150 °C) relatively low for their transformation into CuO and lithium salts. Electrochemically driven lithium insertion/ extraction into/from both Li2CuO2 and LiCuO2 were followed by in situ X-ray diffraction that revealed, for both starting materials, that the Li2CuO2↔ LiCuO2 transitions always proceed through a succession of biphasic and monophasic processes involving three type phases: Li1+yCuO2, "Li1.5CuO2", and Li2-zCuO2. Such a strategy can therefore be used for the preparation of stable copper mixed valence oxides. This study also revealed a very large polarization linked to the Li1.5CuO2 ↔ Li2CuO2 transition. Although so far not explained, this fact enabled us to test the respective reversibility of the LiCuO2↔ Li1.5CuO2 and Li1.5CuO2↔ Li2CuO2 transitions. It was found that performing cycling on both transitions comes with a continuous decrease in the cell capacity while good capacity retention can be obtained when one limits the electrochemical work to the LiCuO2↔ Li1.5CuO2 process.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:16318
Deposited On:15 Nov 2010 13:52
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