Accelerated ageing of electrolytes in Lithium-ion batteries: the point of view of a radiation chemist

International audienceSince the early nineties, the rechargeable Li-ion battery (LIB) technology has dominated the electronic market. These batteries have become essential components in portable electronic applications. Since then, ageing pro cesses are a growing global concern, essentially for their applications in electric and hybrid vehic1es. Ageing phenomena occurring in diethylcarbonate (DEC), DEC/LiPF$_6$ propylene carbonate (PC) and PC/LiPF$_6$ solutions, selected as model systems, have been studied using gamma-and pulse-radiolysis as a tool to generate similar species as the ones occurring in e1ectro1ysis of Li-ion batteries and to mimic the processes (Fig. 1). We prove that similar results were obtained in the ageing of an electrochemical cell filled with the same model solution. This highlights the interest of the radiolysis approach in the field of ageing of electrolytes. Radiolysis has indeed the following major advantages: i) ageing processes are strong1y accelerated (minutes/hours as compared to weeks and months in conventional battery studies); ii) time-resolved experiments are possible, enabling to study the system on multiple temporal scales (from picoseconds to minutes and days). This allows measuring rate constants, and writing very detailed reaction mechanisms; iii) the possibility to study the reactivity of each solvent without/with the salt (of course studies without the salt has no sense in the battery field!), leading to a very accurate understanding of the behavior of the system; iv) the possibility to perform a quick screening of many electrolytes, to identify rapidly the most promising ones. All these points will be discussed

Recent progress in the synthesis of imogolite and imogolite-like clay minerals. A focus on the sphree-tube transition

International audienceImogolite has been discovered more than 50 years ago in the weathering produc of volcanic soils in Japan. It has been quickly realjzed that imogoli lets a ubiquitous clay mineral which can be readly synthesized in the laborarory using ralber simple co-precipitation receipt

Structure et dynamique de la liaison hydrogène dans l'eau confinée ou aux interfaces

International audienceLorsque de l'eau est confinée dans une cavité nanométrique, ses propriétés structurales et dynamiques sont modifiées par rapport à celles de l'eau dans le volume. Les propriétés de l'eau confinée dans des oxydes présentent un intérêt à la fois fondamental et pratique, mais l'état du réseau percolatif dans ces cavités rigides est mal connu. Jusqu'à présent, la majorité des résultats a été obtenue sur de l'eau confinée dans de la matière molle. Nous présenterons ici des résultats obtenus sur la structure et la dynamique de l'eau confinée dans des systèmes rigides comme les oxydes. Pour cela, la spectroscopie infrarouge est une technique de choix, que ce soit par la grande gamme spectrale qu'elle offre (de l'infrarouge lointain, qui permet d'étudier des modes collectifs, au moyen infrarouge avec l'étude de la bande d'élongation O-H), mais aussi par la possibilité de faire des études de spectroscopie d'absorption transitoire femtoseconde qui donnent accès à la durée de vie du vibrateur O-H et à la rotation des molécules d'eau. Ces études ont été réalisées sur l'eau de surface (eau sur une surface d'alumine 1 ou à la surface d'un verre de silice 2 ,3) et l'eau confinée dans des géométries particulières, que ce soit un confinement tridimensionnel comme dans les pores de silice nanométrique 2 ou bidimensionnel comme dans les argiles 4. Les différences de comportement dynamique et de structure du réseau de liaisons hydrogène de l'eau confinée dans des systèmes « durs}) comme les oxydes ou « mous}) comme dans les échantillons biologiques (myoglobine concentrées ...) seront également discutées

Production of H2 by water radiolysis in cement paste under electron irradiation: A joint experimental and theoretical study

International audienceLong-term confinement of nuclear waste is one of the main challenges faced by the nuclear industry. Fission products such as 90 Sr and 137 Cs, both β − emitters known to induce serious health hazards, represent the largest fraction of nuclear waste. Cement is a good candidate to store them, provided it can resist the effects of irradiation over time. Here, we have investigated the effects of β − decay on cement by performing electron irradiation experiments on different samples. We show that H 2 production in cement, the main effect of water radiolysis, depends strongly on composition and relative humidity. First-principles calculations indicate that the water-rich interlayer regions with Ca 2+ ions act as electron traps that promote the formation of H 2. They also show that holes localize in water-rich regions in low Ca content samples and are then able to participate in H 2 production. This work provides new understanding of radiolysis effects in cements

Monoacylglycerol lipase reprograms hepatocytes and macrophages to promote liver regeneration

Background & Aims: Liver regeneration is a repair process in which metabolic reprogramming of parenchymal and inflammatory cells plays a major role. Monoacylglycerol lipase (MAGL) is an ubiquitous enzyme at the crossroad between lipid metabolism and inflammation. It converts monoacylglycerols into free fatty acids and metabolises 2-arachidonoylglycerol into arachidonic acid, being thus the major source of pro-inflammatory prostaglandins in the liver. In this study, we investigated the role of MAGL in liver regeneration. Methods: Hepatocyte proliferation was studied in vitro in hepatoma cell lines and ex vivo in precision-cut human liver slices. Liver regeneration was investigated in mice treated with a pharmacological MAGL inhibitor, MJN110, as well as in animals globally invalidated for MAGL (MAGL-/-) and specifically invalidated in hepatocytes (MAGLHep-/-) or myeloid cells (MAGLMye-/-). Two models of liver regeneration were used: acute toxic carbon tetrachloride injection and two-thirds partial hepatectomy. MAGLMye-/- liver macrophages profiling was analysed by RNA sequencing. A rescue experiment was performed by in vivo administration of interferon receptor antibody in MAGLMye-/- mice. Results: Precision-cut human liver slices from patients with chronic liver disease and human hepatocyte cell lines exposed to MJN110 showed reduced hepatocyte proliferation. Mice with global invalidation or mice treated with MJN110 showed blunted liver regeneration. Moreover, mice with specific deletion of MAGL in either hepatocytes or myeloid cells displayed delayed liver regeneration. Mechanistically, MAGLHep-/- mice showed reduced liver eicosanoid production, in particular prostaglandin E2 that negatively impacts on hepatocyte proliferation. MAGL inhibition in macrophages resulted in the induction of the type I interferon pathway. Importantly, neutralising the type I interferon pathway restored liver regeneration of MAGLMye-/- mice. Conclusions: Our data demonstrate that MAGL promotes liver regeneration by hepatocyte and macrophage reprogramming. Impact and Implications: By using human liver samples and mouse models of global or specific cell type invalidation, we show that the monoacylglycerol pathway plays an essential role in liver regeneration. We unveil the mechanisms by which MAGL expressed in both hepatocytes and macrophages impacts the liver regeneration process, via eicosanoid production by hepatocytes and the modulation of the macrophage interferon pathway profile that restrains hepatocyte proliferation.The authors thank V. Fauveau, Institut Cochin, for help in surgery experiments; Olivier Thibaudeau of the Plateau de Morphologie Facility (INSERM UMR 1152, France) and Nicolas Sorhaindo of the Plateforme de Biochimie (CRI, INSERM UMR1149) for their help in the histology and liver function tests; and K. Bailly from the cytometry platform of Cochin Institute and H. Fohrer-Ting from the Centre de Recherche des Cordeliers, Paris University, for cell sorting analyses.Scopu

Competition between electronic attachment and solvation revealed thanks to radiolysis

International audienceA convenient way to generate charges (electrons and holes) in materials and to study their fate consists in using ionizing radiation. 1 Indeed, ionizing radiation penetrates in the depth of the material, generating charge carriers. During this presentation, we will focus on the behavior of electrons. Once generated, they can either solvate or attach to the molecule(s) of interest. We will illustrate this competition between both processes by two recent examples and show how this affects subsequent reactions

Ageing in Lithium-ion batteries: the point of view of a radiation chemist

International audienceDue to the limited reserves of fossil fuels (natural gas, coal and oil) for its energetic needs and due to environmental concerns, mankind has to use energy in a sustainable manner. Therefore, the conversion and storage of energy is necessary. The most used devices to store energy are now electrochemical batteries. Among them, lithium-ion batteries (LIB) have been commercialized since 1991 and are widely used. That is why the study of ageing and degradation mechanisms in LIB is a crucial issue. Nevertheless, the ageing studies are lengthy, costly, and most often purely qualitative. Recently, we demonstrated that radiolysis (i.e. the chemical reactivity induced by the interaction between matter and ionizing radiation) is a powerful tool for a short-time identification (within minutes-days) of the by-products occurring from the degradation of a LIB electrolyte after several weeks-months of cycling. Indeed, we have shown that the highly reactive species created in the irradiated solution are the same as the ones obtained during the charging of a LIB using similar solvents. More recently, we have used suspensions of electrolyte containing active materials which mimic the surface of the electrode. We have evidenced that these irradiated solutions lead to the formation of a solid electrolyte interface at the surface of the material. Moreover, the simultaneous analysis of the products formed in the gas and in the liquid phase provides a global picture of the phenomena at stake during ageing

Radiolysis of water confined in aluminosilicate nanotubes: importance of charge separation effects

International audienceImogolite nanotubes are potentially promising co-photocatalysts. Indeed, these clays are described as having a wall polarization allowing them to separate the photo-generated charge carriers. We used here radiolysis as a tool for generating charges and studying their fate. Two types of aluminosilicate nanotubes were studied: one is hydrophilic on its external and internal surfaces (IMO-OH), while the other has a hydrophobic internal cavity due to Si-CH$_3$ bonds (IMO-CH$_3$), the outer surface remaining hydrophilic. Picosecond pulsed radiolysis experiments have demonstrated that electrons are efficiently transferred outside the nanotubes. Coupled to gas production measurements as a function of the water content, these experiments have evidenced that, for imogolite samples containing very few water molecules on the outer surfaces (about 1% of the total mass), quasi-free electrons are formed. They attach to a water molecule, generating a radical water anion, which ultimately leads to the formation of dihydrogen. When more external water molecules are present, solvated electrons, precursors to dihydrogen, are formed. The attachment of the quasi-free electron to water is a very efficient process, which accounts for the high production of dihydrogen for low values of relative humidity. When the water content increases, the solvation of electrons is predominant compared to the attachment to water molecules. Solvation of electrons therefore leads to the production of dihydrogen, although to a lower extent than when the precursors are quasi-free electrons. On the other hand, the holes move towards the inner surface of the tubes. They mainly lead to the formation of dihydrogen and methane in irradiated IMO-CH$_3$. Our radiolysis experiments therefore demonstrate the wall-induced spontaneous charge separation in these inorganic nanotubes, making them very interesting potential co-photocatalysts

Confined water in aluminosilicate nanotubes: Structure, dynamics and importance of charge separation effects upon irradiation

International audienceImogolite nanotubes are potentially promising co-photocatalysts because they are predicted to have curvature-induced, efficient electron-hole pair separation. This prediction has however not yet been experimentally proven. Here, we investigated the behavior upon irradiation of these inorganic nanotubes as a function of their water content to understand the fate of the generated electrons and holes. Two types of aluminosilicate nanotubes were studied: one is hydrophilic on its external and internal surfaces (IMO-OH) and the other has a hydrophobic internal cavity due to Si-CH3 bonds (IMO-CH3), with the external surface remaining hydrophilic (AlOH groups). The pre-requisite to such a study is a detailed understanding of the structure and dynamics of water in these nanotubes. Analysis of the O–H stretching band as a function of the relative humidity (RH) provided information on the H bonding of confined water molecules. Adsorption begins in the IMO-OH tubes at the lowest RH (< 10%). The inner surface of the tubes is first covered with water molecules; then, the central part of the tubes is filled, leading to very strong H-bonds. In contrast, the H bonds of water adsorbed on the outer surfaces of these tubes are weaker. Water dynamics in IMO-OH was also revealed by quasi-elastic neutron scattering experiments. When one water monolayer is present on the inner surface, water molecules can jump between neighboring Si-OH sites. When IMO-OH is filled with water, the H-bond network is very rigid, and water molecules are immobile on the timescale of the experiment. A different scenario is observed for water inside IMO-CH3. Weakly H-bonded water molecules are present. Water confinement in imogolites is then governed by the hydrophilicity of the inner walls. Upon irradiation, picosecond pulse radiolysis experiments demonstrated that the electrons are efficiently driven outward. For imogolite samples with very few external water molecules, quasi-free electrons are formed. They are able to attach to a water molecule, which ultimately leads to dihydrogen. When more external water molecules are present, solvated electrons, precursors of dihydrogen, are formed. In contrast, holes move towards the internal surface. The attachment of the quasi-free electron to water is a very efficient process and accounts for the high dihydrogen production at low RH values. Our experiments demonstrate the spontaneous curvature-induced charge separation in these inorganic nanotube

Etude expérimentale et théorique de la structure et de la réactivité de complexes cationiques du fer en phase gazeuse

L'objectif de cette thèse est de caractériser, en phase gazeuse, les facteurs influençant la réactivité de complexes cationiques du fer avec des ligands oxygénés, en particulier de préciser le comportement de ligands bidentates (DXE : diméthoxyéthane CH3OCH2CH2OCH3) par rapport aux analogues monodentates (eau, DME : diméthyléther CH3OCH3). Nous avons utilisé plusieurs méthodes complémentaires: calculs de chimie quantique, expériences de Spectrométrie de Masse par Résonance Cyclotronique Ionique à Transformée de Fourier (FT-ICR) couplées à une analyse bayésienne des données, et plus récemment spectroscopie infra-rouge par dissociation multiphotonique. L'étude expérimentale et théorique des réactions successives des cations Fe(CO)n+ (n = 1-4) avec le ligand montre comment la thermodynamique d'une substitution dépend des autres ligands présents, et pose le problème de l'isomérisation des complexes mixtes par insertion de CO dans la liaison C-O du DME pour donner un ligand ester CH3COOCH3. Les calculs indiquent qu'elle est possible si le métal est entouré par un minimum de trois ligands. Cependant, le spectre infra-rouge de Fe+(CO)(DME)2 montre l'absence d'une telle insertion, ce qui suggère qu'une barrière énergétique importante lui est associée. L'ion Fe(DME)+ réagit sur un deuxième ligand DME avec rupture de la liaison C-O. Deux voies sont en compétition: rupture homolytique de C-O conduisant à Fe(OCH3)(DME)+, ou rupture avec réarrangement donnant l'ion Fe(CH2O)(DME)+ après la perte d'une molécule de méthane. Les proportions relatives des deux produits sont extrêmement dépendantes de l'énergie du système [Fe(DME)+, DME], la perte de méthane étant d'autant plus favorisée que cette énergie est basse. Le complexe bidentate Fe(DXE)+ se différencie nettement de Fe(DME)+ : par réaction avec un deuxième ligand, seule la formation de Fe(CH2O)(DXE)+ est observée. Nous avons montré que l'insertion du métal dans la liaison C-O est régiosélective et implique un carbone central.This thesis aims at characterizing the reactivity of cationic iron complexes with oxygenated molecules in the gas phase, and at comparing the behavior of bidentate ligands (DXE : dimethoxyethane CH3OCH2CH2OCH3) and monodentate ones (water, DME : dimethylether CH3OCH3). Thus, chemical quantum calculations were performed, in combination with Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT -ICR) experiments coupled to bayesian data analysis, and structural characterization by means of Infra-Red MultiPhoton Dissociation (IRMPD) spectroscopy. Primary reactions of Fe(CO)n+ (n = 1-4) with the ligand are substitutions. We have shown that the thermodynamics of these reactions depends on the other ligands. For n = 3-4 the last CO substitution by one water or dimethylether molecule is never observed, in good agreement with electronic structure calculations, suggesting that the last substitution is not thermodynamically favored for n > 2. The calculations suggest that a CO insertion into the C-O bond of dimethylether, leading to an ester CH3COOCH3 ligand is possible when the metallic center is surrounded by at least three ligands. Nevertheless, the infra-red spectrum of Fe+(CO)(CH3OCH3)2 proves that such an insertion did not take place, showing that the associated barriers are too high in energy. We have found that the Fe(DME)+ ion reacts with DME through two competing C-O bond cleavages. The first one is an homolytic cleavage, leading to the formation of Fe(OCH3)(DME)+; whereas the second corresponds to a rearrangement, involving methane loss and leading to the formation of Fe(CH2O)(DME)+. The corresponding branching ratio is very sensitive to the energy of the [Fe(DME)+, DME] system, the loss of methane being favored when its energy is low. In comparison, the behavior of Fe(DXE)+ is very different, since the only ion detected is Fe(CH2O)(DXE)+. We have proven that the insertion of Fe+ in the C-O bond is regioselective, the C atom being a central one.LILLE1-BU (590092102) / SudocORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF