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Contribution à l'étude des phases Lix(Co,M)O2 en tant que matériaux d'électrode positive des batteries Li-ion. Effets combinés de la surstoechiométrie en lithium et de la substitution (M = Ni, Mg)

Abstract : Lix0(Co,M)O2 (M = Ni, Mg ; x0 ≥ 1.0) materials used as positive electrode for Li-ion batteries have been prepared at high temperature (900° C) and characterised by X-ray diffraction, galvanostatic measurements, 7Li MAS NMR spectroscopy and electrical properties measurements. If the results on the LiCoO2 phase agree with the literature, the adding of an excess of lithium during synthesis leads to the presence in the actual materials to the presence of oxygen vacancies and intermediate spin Co3+ ions (Co3+(IS)) in a square-based environment. This defect suppresses all the phase transitions usually observed upon lithium deintercalation in LixCoO2. The partial substitution by Ni ions allows us to separate the relative contribution of NiIII and Co3+(IS) ions in the suppression of the various phase transitions upon cycling. Mg doping, even without any lithium excess, systematically induces some oxygen vacancies and Co3+(IS) ions in the material. This observation had been correlated to the behaviour of the Lix(Co,Mg)O2 system upon cycling.
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Submitted on : Wednesday, October 8, 2003 - 6:23:45 PM
Last modification on : Thursday, January 11, 2018 - 6:15:07 AM
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Stéphane Levasseur. Contribution à l'étude des phases Lix(Co,M)O2 en tant que matériaux d'électrode positive des batteries Li-ion. Effets combinés de la surstoechiométrie en lithium et de la substitution (M = Ni, Mg). Autre. Université Sciences et Technologies - Bordeaux I, 2001. Français. ⟨tel-00003507⟩

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