Marine Reynaud

• PhD in Materials Science
• PostDoc Position at CIC Energigune

We report the preparation and electrochemical properties of Na3V(PO3)3N made by ammonolysis. Na3V(PO3)3N is reversibly oxidized to Na2V(PO3)3N at high voltage (4.0 V vs. Na⁺/Na⁰ and 4.1 V vs. Li⁺/Li⁰) with an unusually small difference in the insertion/extraction voltage between both alkali metal reference electrodes. In both cases, the voltage hys...

The program FAULTS has been used to simulate the X-ray powder diffraction (XRD), neutron powder diffraction (NPD), and electron diffraction (ED) patterns of several structural models for LiNi 1/3 Mn 1/3 Co 1/3 O 2 , including different types of ordering of the transition metal (TM) cations in the TM slabs, different amounts of Li ⁺ /Ni II+ cation m...

The FAULTS program is a powerful tool for the refinement of diffraction patterns of materials with planar defects. A new release of the FAULTS program is herein presented, together with a number of new capabilities, aimed at improving the refinement process and evolving towards a more user-friendly approach. These include the possibility to refine...

We report herein on the magnetic properties and structures of orthorhombic Li2M(SO4)2 (M = Co, Fe) and their oxidized phases LixFe(SO4)2 (x = 1, 1.5), which were previously studied as potential cathode materials for Li-ion batteries. The particular structure of these orthorhombic compounds (space group Pbca) consists of a three-dimensional network...

The quest for new sustainable iron-based positive electrode materials for lithium-ion batteries recently led to the discovery of a new family of compounds with the general formula Li2M(SO4)2 with M = transition metal, which presents monoclinic and orthorhombic polymorphs. In terms of electrochemical performances, although both Li2Fe(SO4)2 polymorph...

As part of a broad project to explore Li4MM’O6 materials (with M and M’ being selected from a wide variety of metals) as positive electrode materials for Li-ion batteries, the structures of Li4FeSbO6 materials with both stoichiometric and slightly lithium-deficient are studied here. For lithium content varying from 3.8 to 4.0 the color changes from...

A new orthorhombic polymorph of Li2Fe(SO4)2 is prepared by high-energy ball milling of stoichiometric amounts of FeSO4 and Li2SO4 which results in well crystallized samples without noticeable amounts of the precursors after 5—10 h.

To enhance the safety, cost, and energy density of Li-ion batteries, significant research efforts have been devoted to the search for new positive electrode materials that exhibit high redox potentials and are composed of low-cost, earth-abundant elements. Sulfate chemistry has yielded promising results for iron-based polyanionic electrode material...

The search for high voltage cathodes for lithium-ion batteries has led to recent interest in the monoclinic Li2Fe(SO4)2 material which has a voltage of 3.83 V vs. lithium, the highest recorded for a fluorine-free iron-based compound. Here we investigate the defect, surface and lithium migration properties of the Li2M(SO4)2 (M = Fe, Mn, Co) material...

Li-ion batteries have enabled a revolution in the way portable consumer-electronics are powered and will play an important role as large-scale electrochemical storage applications like electric vehicles and grid-storage are developed. The ability to identify and design promising new positive insertion electrodes will be vital in continuing to push...

Mineralogy offers a large database to search for Li- or Na-based compounds having suitable structural features for acting as electrode materials, LiFePO4 being one example. Here we further explore this avenue and report on the electrochemical properties of the bloedite type compounds Na2M(SO4)2[middle dot]4H2O (M = Mg, Fe, Co, Ni, Zn) and their deh...

In this paper, we report on the structural and magnetic properties, as deduced from susceptibility measurements and neutron powder diffraction experiments, of an orthorhombic nickel disulfate, Li2Ni(SO4)2. This phase presents NiO6 octahedra linked via SO4 groups only, leading to an antiferromagnetic behavior resulting from super-super-exchange inte...

The next generations of Li- and Na-ion batteries will rely on the development of new sustainable, low-cost and safe positive electrode materials. To this end, we explored the world of minerals with an emphasis on spotting structures having the prerequisites for insertion and deinsertion of alkaline ions. From this survey, we embarked on the investi...

The title compounds are investigated by powder X-ray and powder neutron diffraction and magnetic susceptibility measurements.

New materials initially designed for battery electrodes are often of interest for magnetic study, because their chemical compositions include 3d transition metals. We report here on the magnetic properties of marinite phases Li2M(SO4)2 (M = Fe, Co, Mn) and Li1Fe(SO4)2, which all order antiferromagnetically at low temperature. From neutron powder di...

Developing the next generations of Li- and Na-ion batteries relies on designing new sustainable, low-cost and safe electrode materials. In such an attempt, we investigated several series of bimetallic sulfates, among them we identified Na2Fe(SO4)(2)center dot 4H(2)O, Na2Fe(SO4)(2) and Li2Fe(SO4)(2), which present attractive electrochemical properti...

Developing the next generations of Li-and Na-ion batteries relies on designing new sustainable, low-cost and safe electrode materials. In such an attempt, we investigated several series of bimetallic sulfates, among them we identified Na 2 Fe(SO 4) 2 ·4H 2 O, Na 2 Fe(SO 4) 2 and Li 2 Fe(SO 4) 2 , which present attractive electrochemical properties...

The development of new electrode materials, which are composed of Earth-abundant elements that can be made via eco-efficient processes, is becoming absolutely necessary for reasons of sustainable production. The 3.9 V triplite-phase of LiFeSO4F, compared to the 3.6 V tavorite-phase, could satisfy this requirement provided the currently complex synt...

We report on the preparation and electrochemical characterization of Li 2 M(SO 4) 2 (M=Co, Fe), where the Fe-based phase was previously unknown. Both compounds can be made at low temperatures (b 320 °C) and the Fe-based phase displays an open circuit voltage of 3.83 V vs. Li + /Li 0 for the Fe 3+ /Fe 2+ redox potential. This corresponds to the high...

The new compounds (III), (VI), and (IX) crystallize as their Fe and Co counterparts with the maxwellite structure (tavorite-like framework) in the monoclinic space group C2/c.

Our work in metal fluorosulphate chemistry, which was triggered by the discovery of the tavorite-phase of LiFeSO4F, has unveiled many novel Li- and Na-based phases with desirable electrochemical and/or transport properties. Further exploring this rich crystal chemistry, we have synthesized the Na-based magnesium, copper and zinc fluorosulphates, wh...

Recently in the Li-ion battery community there has been an intense amount of attention focusing on developing positive electrodes which operate on the Fe2+/Fe3+ redox potential given that the environmental and economic advantages of Fe-based compounds compared to other transition metals are tremendous. Here we report that we have succeeded in prepa...

CoSeO4 is prepared by neutralizing a solution of selenic acid with Co2(CO3)x(OH)y at 70 °C and used as precursor for the synthesis of NaCoSeO4F·2H2O by reaction with a stoichiometric amount of NaF at 80 °C.

A novel hydrated fluoroselenate NaCoSeO(4)F·2H(2)O has been synthesized, and its structure determined. Like its sulfate homologue, NaCoSO(4)F·2H(2)O, the structure contains one-dimensional chains of corner-sharing MO(4)F(2) octahedra linked together through F atoms sitting in a trans configuration with respect to each other. The magnetic properties...

Recently unveiled ‘alkali metal fluorosulphate (AMSO4F)’ class of compounds offers promising electrochemical and transport properties. Registering conductivity value as high as 10−7 S cm−1 in NaMSO4F phases, we explored the fluorosulphate group to design novel compounds with high Li-ion conductivity suitable for solid electrolyte applications. In t...

Wrapped in IL: Solid electrolytes are key for safer lithium batteries. The novel LiZnSO4F fluorosulfate prepared by an ionic-liquid-assisted synthesis delivers high ionic conductivity at room temperature (see picture). The lithium-containing ionic-liquid layer tailors the ionic conductivity of inorganic composites by a surface effect. This finding...

Searching for possible new cathode materials with the ability to outperform LiFePO4, our group has recently discovered LiFeSO4F, a novel metal fluorosulphate compound. Needing no further optimization, it delivers excellent reversible capacity (similar to 140 mAh/g) involving a 3.6 V Fe-II/III redox plateau. This parent fluorosulphate phase has been...