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Theses

Développement d’accumulateur nouvelle génération Mg ion

Abstract : This PhD thesis aims to develop Mg-Ion cathode materials. Once the electrolyte selected and the electrochemical characterization system established, two insertion materials families were studied: Chevrel phases and manganese dioxides.The Chevrel phases Mo6S8 and Mo6Se8 have been the subject of a coupled electrochemistry / XPS ex situ understanding study. The two phases were characterized by voltammetry, GITT and PITT showing diffusion coefficients ranging from 10-11 to 10-14 cm2.s-1. Unconventional redox mechanisms were observed by XPS studies indicating a charge transfer inside the anions in addition to the reduction of the transition metals. The comparison of the two materials Mo6S8 and Mo6Se8 indicates the sulfur is more involved in the charge transfer than the selenium.In the second part, two MnO2 promising structures have been selected and studied: hollandite and birnessite. We evidenced that electrolyte hydratation is needed to allow the insertion inside the different MnO2 structures. RMN 1H and XPS analyses revealed a co-insertion phenomenon involving Mg2+ cations and H2O molecules. However, these compounds exhibit a poor cyclability and irreversible capacities of 50% to 80%. This understanding work is a first step towards the design of new reversible insertion materials for Mg-Ion batteries.
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https://tel.archives-ouvertes.fr/tel-01864508
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Submitted on : Thursday, August 30, 2018 - 9:39:06 AM
Last modification on : Tuesday, May 19, 2020 - 9:42:01 AM

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RICHARD_2017_archivage.pdf
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  • HAL Id : tel-01864508, version 1

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Citation

Julien Richard. Développement d’accumulateur nouvelle génération Mg ion. Matériaux. Université Grenoble Alpes, 2017. Français. ⟨NNT : 2017GREAI125⟩. ⟨tel-01864508⟩

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