Browsing by Author "Dubouis, N"

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    Crystallographic and magnetic structures of the VI3 and LiVI3 van der Waals compounds
    (American Physical Society, 2021-07-12) Marchandier, T; Dubouis, N; Fauth, F; Avdeev, M; Grimaud, A; Tarascon, JM; Rousse, G
    Two-dimensional (2D) layered magnetic materials are generating a great amount of interest for the next generation of electronic devices thanks to their remarkable properties associated with spin dynamics. The recently discovered layered VI3 ferromagnetic phase belongs to this family, although a full understanding of its properties is limited by the incomplete understanding of its crystallographic structure. The motivation of this work is to address this issue. Here, we investigate the VI3 crystal structures at low temperature using both synchrotron x-ray and neutron powder diffraction and provide structural models for the two structural transitions occurring at 76 and 32 K. Moreover, we confirm by magnetic measurements that VI3 becomes ferromagnetic at 50 K and we question the establishment of a long-range magnetic structure by neutron diffraction. We equally determined the magnetic properties of our recently reported LiVI3 phase, which is like the well-known CrI3 ferromagnetic phase in terms of electronic and crystallographic structures and found an antiferromagnetic behavior with a Néel temperature of 12 K. Such a finding provides extra clues for a better understanding of magnetism in these low-dimension compounds. Finally, the easiness of preparing Li-based 2D magnetic materials by chemical/electrochemical means opens wide the opportunity to design materials with exotic properties. ©2021 American Physical Society
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    Extending insertion electrochemistry to soluble layered halides with superconcentrated electrolytes
    (Springer Nature, 2021-07-29) Dubouis, N; Marchandier, T; Rousse, G; Marchini, F; Fauth, F; Avdeev, M; Iadecola, A; Porcheron, B; Deschamps, M; Tarascon, JM; Grimaud, A
    Insertion compounds provide the fundamental basis of today’s commercialized Li-ion batteries. Throughout history, intense research has focused on the design of stellar electrodes mainly relying on layered oxides or sulfides, and leaving aside the corresponding halides because of solubility issues. This is no longer true. In this work, we show the feasibility of reversibly intercalating Li+ electrochemically into VX3 compounds (X = Cl, Br, I) via the use of superconcentrated electrolytes (5 M LiFSI in dimethyl carbonate), hence opening access to a family of LixVX3 phases. Moreover, through an electrolyte engineering approach, we unambiguously prove that the positive attribute of superconcentrated electrolytes against the solubility of inorganic compounds is rooted in a thermodynamic rather than a kinetic effect. The mechanism and corresponding impact of our findings enrich the fundamental understanding of superconcentrated electrolytes and constitute a crucial step in the design of novel insertion compounds with tunable properties for a wide range of applications including Li-ion batteries and beyond. © 2021 Springer Nature Limited
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    Superconcentrated electrolytes widens insertion electrochemistry to soluble layered halides
    (Cambridge University Press, 2021-03-25) Dubouis, N; Marchandier, T; Rousse, G; Marchini, F; Fauth, F; Avdeev, M; Iadecola, A; Porcheron, B; Deschamps, M; Tarascon, JM; Grimaud, A
    Insertion compounds provide the fundamental basis of today’s commercialized Li-ion batteries. Throughout history, intense research has focus on the design of stellar electrodes mainly relying on layered oxides or sulfides, and leaving aside the corresponding halides because of solubility issues. This is no longer true. In this work, we show for the first time the feasibility to reversibly intercalate electrochemically Li+ into VX3 compounds (X = Cl, Br, I) via the use of superconcentrated electrolytes, (5 M LiFSI in dimethyl carbonate), hence opening access to a novel family of LixVX3 phases. Moreover, through an electrolyte engineering approach we unambiguously prove that the positive attribute of superconcentrated electrolytes against solubility of inorganic compounds is rooted in a thermodynamic rather than a kinetic effect. The mechanism and corresponding impact of our findings enrich the fundamental understanding of superconcentrated electrolytes and constitute a crucial step in the design of novel insertion compounds with tunable properties for a wide range of applications beyond Li-ion batteries. The content is available under CC BY NC ND 4.0 License CreativeCommons.org.