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Lithium nitridonickelate as anode coupled with argyrodite electrolyte for all-solid-state lithium-ion batteries
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Les éléments métalliques et les poussières minérales des « matières noires » : nouveaux marqueurs des pratiques funéraires de l’Égypte ancienne
No full textThe materials hereafter called "black matters" were used in ancient Egypt in funerary context. They consist of complex mixtures of natural substances, of which only the bio-organic component has been studied up until now. Detecting bitumen in black matters proves challenging through micro-destructive molecular analysis and entrapped mineral dust has remained unstudied until now.Using an exploratory, innovative and multitechnique approach, reference asphalt and heritage black matters samples from various museum corpuses underwent analysis using Electron Paramagnetic Resonance (EPR) and Ion Beam Analysis (IBA). The relevance of PIXE/EPR coupling has been demonstrated in determining bitumen presence and origin and quantifying bitumen by detecting metallic elements (V, Ni, Mo) and paramagnetic molecules (vanadyl porphyrins, carbon radicals). Furthermore, an enrichment in heavy metallic elements observed in several black matters raises the question of their potential additions due to their biocidal properties.Particular attention was paid to black matters from the Boulogne-sur-Mer museum, which quite unusually consist entirely of pure bitumen. The detection of cuprorivaite and mineral dust by PIXE/IBIL coupling in these matters confirmed their original character. Finally, recreation experiments revealed the formation of non-porphyrinic complexes, serving as potential markers of the interaction between organic and inorganic black matters components. Perspectives opened up by this research include transitioning towards a non-invasive or even in situ approach and expending the studied corpus to determine the mummification site through entrapped mineral dust study.Les matières dénommées « matières noires » dans cette recherche ont été employées dans l’Égypte ancienne en contexte funéraire, et sont des mélanges complexes de substances naturelles dont seule la composante bio-organique avait été jusqu’ici caractérisée. Le bitume présent dans les matières noires est difficile à détecter par l’analyse moléculaire micro-destructive, et les poussières minérales qui ont pu y être emprisonnées n'avaient pas été étudiées jusqu'à présent. Selon une approche exploratoire, novatrice et multi-techniques, des échantillons d’asphalte de référence et de matières noires patrimoniales issues de divers corpus muséaux ont été analysés par Résonance Paramagnétique Électronique (RPE) et analyse par faisceaux d’ions (IBA). L'intérêt du couplage PIXE/RPE a été démontré pour déterminer la présence et la provenance ainsi que pour quantifier le bitume, via la détection d’éléments métalliques (V, Ni, Mo) et de molécules paramagnétiques (porphyrines de vanadyle, radicaux carbonés). De plus, un enrichissement en éléments lourds métalliques observé dans plusieurs matières noires soulève la question de leurs possibles additions en raison de leurs propriétés biocides. Une attention particulière a été portée aux matières noires d’embaumement de la momie du musée de Boulogne-sur-Mer, singulières car entièrement constituées de bitume pur. La détection de cuprorivaïte et de poussières minérales dans ces matières par couplage PIXE/IBIL en a confirmé le caractère original. Enfin, des expériences de recréations ont révélé la formation de complexes non-porphyriniques comme possibles marqueurs de l'interaction entre les constituants organiques et inorganiques des matières noires. Les perspectives ouvertes par cette recherche incluent l’évolution vers une approche analytique non invasive voire in situ, et l’augmentation du corpus étudié pour parvenir à déterminer le lieu de momification via l'étude des poussières minérales piégées
Carbon black structural effect within kraft black liquor-based poly(HIPE): enhanced hydrogen storage and electro-capacitive properties
No full textInternational audienceA biopolymer derived from Kraft Black Liquor (KBL), a byproduct of the paper industry composed mainly of lignin and hemicellulose, has been successfully filled with three different types of carbon black (CB) that differ in their specific surface areas, sizes, shapes and surface heteroatoms. These composite CB–KBL dispersions have been subsequently employed to generate porous monoliths through an emulsion-polymerization templating process. After carbonization, the fillers' influence over the resulting carbon monolith structures and textures is investigated. In particular, beyond XRD, Raman spectroscopy demonstrates improved sample structuration through CB filler addition while nitrogen sorption measurements reveal the influence of the fillers over the final composite's porosities. Considering their properties and effectiveness, hydrogen storage at 77 K reveals that some materials offer up to 1.4 wt% of H2 storage capacity, being higher than that of some commercial carbon materials (with the same specific surface) offering 1.2 wt% hydrogen retention. When addressing their electrochemical energy storage properties, some of these electrode materials deliver extremely promising specific capacities and rate capabilities, with values up to 47 mA h g−1 at 1 A g−1 in alkaline electrolyte, higher than those of the well-known “YP-80F” commercial material tested under the same conditions. These enhanced energy storage properties, while employing a high tonnage paper industry by-product as a carbonaceous source and carbon blacks as structural and textural modifiers, render these materials realistic candidates favoring a sustainable energy transition
Direct determination of electron and hole temperatures from continuous-wave photoluminescence measurements
No full textInternational audienceHot-carrier solar cells offer potential for enhancing the energy-conversion efficiency of photovoltaic devices, but their design and operation require a good assessment of carrier temperatures. Electrons and holes may have different temperatures, for instance because of their effective mass mismatch in III-V compounds. We propose a purely optical method which allows the direct and distinct estimation of electron and hole temperatures in steady state. This technique, based on photoluminescence, relies on the precise determination of the band-filling signature. We apply this technique to an InGaAsP single quantum well. Electron temperature surpasses 1000 K at largest excitation intensity, while holes remain colder, close to lattice temperature. Nonetheless, the increase in hole temperature is too large to be explained purely by photon absorption, which demonstrates an energy transfer from electrons to holes
Introduction à la programmation Python pour la biologie
No full text1. Introduction2. Variables3. Affichage4. Listes5. Boucles et comparaisons6. Tests7. Fichiers8. Dictionnaires et tuples9. Modules10. Fonctions11. Plus sur les chaînes de caractères12. Plus sur les listes13. Plus sur les fonctions14. Conteneurs15. Création de modules16. Bonnes pratiques en programmation Python17. Expressions régulières18. Jupyter et ses notebooks19. Module Biopython20. Module NumPy21. Module Matplotlib22. Module Pandas23. Avoir la classe avec les objets24. Avoir plus la classe avec les objets25. Fenêtres graphiques et Tkinter26. Remarques complémentaires27. Mini-projetsAnnexesA. Quelques formats de données rencontrés en biologieB. Installation de PythonMaste
The spontaneous passivation of (CoFeNi) (1-x)/3 Cr x alloys in sulfuric acid
No full textInternational audienceThe influence of %Cr on the spontaneous passivation of (CoFeNi) (100-x)/3Crx alloys in 0.1 M H2SO4 was investigated. During spontaneous passivation, Cr enrichment occurs due to the selective dissolution of the matrix elements. The quantity of Cr enrichment is relatively constant with Cr content while the total quantity of alloy dissolved decreases with increasing Cr content. Oxygen reduction is the main driving force for the oxidation / passivation of the alloy at open circuit. %Cr has little effect on the kinetics of oxygen reduction. Element resolved polarization curves predict spontaneous passivation by comparing the critical dissolution rate with the cathodic current
On the atomic structure of monolayer VCT and the study of charge storage processes in an acidic electrolyte using SPEIS and in-situ X-ray absorption spectroscopy
No full textInternational audienceMonolayer VCT is synthesized and its atomic structure is studied using high-end transmission electron microscopy. X-Ray diffraction reveals key 3D to 2D crystal transformations as a VAlC crystal is transformed into VCT in synthesis processes. The charge storage properties of VCT film electrodes are investigated for supercapacitor applications in 3 M HSO. VCT film electrodes shows an excellent capacitance of up to 469.6 F g and 845.7 F cm, rate performance up to 30 A g and cycling stability up to 10,000 cycles. A combination of electrochemical kinetics/mass transport models, staircase potentio-electrochemical impedance spectroscopy and in situ X-Ray absorption spectroscopy reveals, for the first time for this MXene, the underlying charge storage mechanisms, consisting of double layer capacitance, pseudocapacitance and a minor contribution from mass transport-controlled processes. The latter two implying a outstanding redox activity superior to Ti-based MXenes. The stability in standard environments, mechanical flexibility and the demonstrated excellent charge storage performance of VCT makes it one of the best candidates for supercapacitor applications, especially in miniaturized devices
Electrolytic Micro‐Capacitors Based on Tantalum Films for High Voltage Applications
No full textInternational audienceElectrolytic capacitors are known to be fast devices with very low time constant and able to deliver high power. This class of capacitors is then an interesting technology to power miniaturized embedded electronics for Internet of Things applications. However, the current electrolytic capacitor suffers from its bulky size that does not fit with the miniaturization. To solve this issue, a proof-of-concept consisting of miniaturizing an electrolytic capacitor based on tantalum materials to give rise to a new class of electrolytic micro-capacitors is proposed. To reach this ambitious objective, thin films (<100 nm) of tantalum metal (Ta), tantalum nitride (TaN), and tantalum oxide (Ta2O5) are deposited on a Si substrate by sputtering deposition method. After a careful optimization of the deposition parameters, Ta/Ta2O5 and TaN/Ta2O5 electrodes (Ta and TaN ≈45 nm and Ta2O5 ≈25 nm) and study their behaviors when biased at high voltage (>20 Volts) in aqueous electrolyte are produced. The Ta/Ta2O5 and TaN/Ta2O5 interfaces when the electrode is polarized near and beyond the breakdown voltage of the dielectric layer are carefully investigated. Polarizing the electrodes beyond the breakdown voltage are shown to result in anodization-like mechanisms. In the case of the TaN/Ta2O5 electrode, an N-rich porous layer grew within the Ta2O5 layer as polarization increased. A comparative study on the 2 stacked layers electrodes with different compositions (Ta/Ta2O5 and TaN/Ta2O5) but similar thicknesses (45/25 nm) is carried out: both electrodes show excellent capacitance retention of over 90% over 300 000 cycles. The frequency behavior of Ta/Ta2O5 and TaN/Ta2O5 electrodes shows that both are potential candidates in electrolytic micro-capacitors for powering miniaturized electronics
Donnan equilibrium in charged slit-pores from a hybrid nonequilibrium molecular dynamics/Monte Carlo method with ions and solvent exchange
No full textInternational audienceIon partitioning between different compartments (e.g., a porous material and a bulk solution reservoir), known as Donnan equilibrium, plays a fundamental role in various contexts such as energy, environment, or water treatment. The linearized Poisson–Boltzmann (PB) equation, capturing the thermal motion of the ions with mean-field electrostatic interactions, is practically useful to understand and predict ion partitioning, despite its limited applicability to conditions of low salt concentrations and surface charge densities. Here, we investigate the Donnan equilibrium of coarse-grained dilute electrolytes confined in charged slit-pores in equilibrium with a reservoir of ions and solvent. We introduce and use an extension to confined systems of a recently developed hybrid nonequilibrium molecular dynamics/grand canonical Monte Carlo simulation method (“H4D”), which enhances the efficiency of solvent and ion-pair exchange via a fourth spatial dimension. We show that the validity range of linearized PB theory to predict the Donnan equilibrium of dilute electrolytes can be extended to highly charged pores by simply considering renormalized surface charge densities. We compare with simulations of implicit solvent models of electrolytes and show that in the low salt concentrations and thin electric double layer limit considered here, an explicit solvent has a limited effect on the Donnan equilibrium and that the main limitations of the analytical predictions are not due to the breakdown of the mean-field description but rather to the charge renormalization approximation, because it only focuses on the behavior far from the surfaces
Supercritical ionothermal relithiation of Li1-x(Ni0.6Mn0.2Co0.2)O2 positive electrode materials for Li-Ion Battery Direct Recycling
No full textInternational audienceIn response to the escalating demand for Li-ion batteries, the management of their end-of-life has emerged as a critical concern..