Browsing by Author "Rousse, G"
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- ItemCrystallographic 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, GTwo-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
- ItemExtending 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, AInsertion 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
- ItemMagnetic properties, magnetic structure, and possible magnetoelectric effect in orthorhombic corundumlike Li2Ni2W2O9(American Physical Society, 2024-02-08) Redor, S; Avdeev, M; Hrabovsky, D; Tarascon, JM; Rousse, GThe magnetoelectric effect is an appealing property displayed by most compounds in the corundum-derived 429 series (M4A2O9, A=Nb or Ta). The exception is Ni4Nb2O9, crystallizing in the orthorhombic Pbcn space group: because of symmetry considerations, its magnetic space group forbids the occurrence of the magnetoelectric effect. Li2Ni2W2O9 crystallizes in the same space group as Ni4Nb2O9; however, as half the Ni2+ cations are replaced by Li+ cations, the interactions between the remaining magnetic elements are drastically modified. In this paper, we present the results of magnetic bulk measurements, showing an antiferromagnetic ordering coupled with strong ferromagnetic interactions below TN≈8K in Li2Ni2W2O9. Through neutron diffraction, the magnetic structure of Li2Ni2W2O9 is solved, and it is confidently established that it presents the Pb′c′n′ Shubnikov space group (#60.425), whose point symmetry m′m′m′ allows the magnetoelectric effect. This could possibly open the door to a family of magnetoelectric, orthorhombic compounds. ©2024 American Physical Society
- ItemNeutron diffraction study of the li-ion battery cathode Li2FeP2O7(American Chemical Society, 2013-03-18) Barpanda, P; Rousse, G; Ye, T; Ling, CD; Mohamed, Z; Klein, Y; Yamada, AWith a combination of magnetic susceptibility measurements and low-temperature neutron diffraction analyses, the magnetic structure of Li2FeP2O7 cathode has been solved. This pyrophosphate Li2FeP2O7 compound stabilizes into a monoclinic framework (space group P2(1)/c),having a pseudolayered structure with the constituent Li/Fe sites distributed into MO6 and MO5 building units. The magnetic susceptibility follows a Curie Weiss behavior above 50 K. Li2FeP2O7 shows a long-range antiferromagnetic ordering at T-N = 9 K, as characterized by the appearance of distinct additional peaks in the neutron diffraction pattern below TN. Its magnetic reflections can be indexed with a propagation vector k = (0,0,0). The magnetic moments inside the FeO6-FeO5 clusters are ferromagnetic, whereas these clusters are antiferromagnetic along the chains. The adjacent chains are in turn ferromagnetically arranged along the a-axis. The magnetic structure of Li2FeP2O7 cathode material is described focusing on their localized spin spin exchange. The magnetic structure and properties have been generalized for Li2FeP2O7 Li2CoP2O7 binary solid solutions. © 2013, American Chemical Society.
- ItemSuperconcentrated 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, AInsertion 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.
- ItemUnlocking anionic redox activity in O3-type sodium 3d layered oxides via Li substitution(Springer Nature, 2021-01-11) lorem, Ipsum; Wang, Q; Mariyappan, S; Rousse, G; Morozov, AV; Porcheron, B; Dedryvère, R; Wu, JP; Yang, WL; Zhang, LT; Chakir, M; Avdeev, M; Deschamps, M; Yu, YS; Cabana, J; Doublet, ML; Abakumov, AM; Tarascon, JMSodium ion batteries, because of their sustainability attributes, could be an attractive alternative to Li-ion technology for specific applications. However, it remains challenging to design high energy density and moisture stable Na-based positive electrodes. Here, we report an O3-type NaLi1/3Mn2/3O2 phase showing anionic redox activity, obtained through a ceramic process by carefully adjusting synthesis conditions and stoichiometry. This phase shows a sustained reversible capacity of 190 mAh g−1 that is rooted in cumulative oxygen and manganese redox processes as deduced by combined spectroscopy techniques. Unlike many other anionic redox layered oxides so far reported, O3-NaLi1/3Mn2/3O2 electrodes do not show discernible voltage fade on cycling. This finding, rationalized by density functional theory, sheds light on the role of inter- versus intralayer 3d cationic migration in ruling voltage fade in anionic redox electrodes. Another practical asset of this material stems from its moisture stability, hence facilitating its handling and electrode processing. Overall, this work offers future directions towards designing highly performing sodium electrodes for advanced Na-ion batteries. © 2021, The Author(s), under exclusive licence to Springer Nature Limited.