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Modélisation du comportement électrochimique de matériaux pour batteries au lithium à partir de calculs de premiers principes

Abstract : The functioning of a positive electrode in a lithium battery is based on the reversible intercalation of lithium. In some cases, such a reaction can lead to important structural modifications and therefore to an amorphization of the material. A theoretical approach is presented here that leads to structural predictions and simulations of electrochemical behaviour of positive electrode materials. In the first part, DFT (Density Functional Theory) formalisms and the respective advantages of FLAPW (Full potential Linearized Augmented Plane Waves) and PP/PW (Pseudopotential / Plane Waves) methods are discussed. In the second part are given some fundamental electrochemistry considerations related to the intercalation process, thermodynamics aspects and relationships with electronic structure. Then, an approach combining experimental data and geometry optimisation of structural hypotheses is given. This approach was first applied to a model compound LiMoS2, and has been then generalised to systems of industrial interest such as LixV2O5 (0 ≤ x ≤ 3). The simulated X-ray diagrams of the optimised structures for LiMoS2 and ω- Li3V2O5 are in good agreement with experimental data. In the case of LixV2O5, the first discharge curves starting from α-V2O5 and γ'-V2O5 were then successfully simulated. A chemical bond analysis was carried out to help understand the origin of the distortion in LiMoS2 and the voltage variations in the electrochemical curves of LixV2O5. This study clearly demonstrates that an approach combining first-principle calculations and available experimental data is invaluable in the structure determination of poorly crystallised compounds. Such a procedure contributes to the understanding of the phase transitions induced by the lithium intercalation in vanadium oxide compounds and can really be used in the research of new battery materials.
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https://tel.archives-ouvertes.fr/tel-00003977
Contributor : Xavier Rocquefelte <>
Submitted on : Monday, December 15, 2003 - 5:07:13 PM
Last modification on : Friday, October 23, 2020 - 4:45:21 PM
Long-term archiving on: : Friday, April 2, 2010 - 7:28:35 PM

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  • HAL Id : tel-00003977, version 1

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Xavier Rocquefelte. Modélisation du comportement électrochimique de matériaux pour batteries au lithium à partir de calculs de premiers principes. Matériaux. Université de Nantes, 2001. Français. ⟨tel-00003977⟩

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