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Material characterization methods for investigating charge storage processes in 2D and layered materials-based batteries and supercapacitors
No full textInternational audienceTwo-dimensional (2D) materials offer distinct advantages for electrochemical energy storage (EES) compared to bulk materials, including a high surface-to-volume ratio, tunable interlayer spacing, and excellent in-plane conductivity, making them highly attractive for applications in batteries and supercapacitors. Gaining a fundamental understanding of the energy storage processes in 2D material-based EES devices is essential for optimizing their chemical composition, surface chemistry, morphology, and interlayer structure to enhance ion transport, promote redox reactions, suppress side reactions, and ultimately improve overall performance. This review provides a comprehensive overview of the characterization techniques employed to probe charge storage mechanisms in 2D and thin-layered material-based EES systems, covering optical spectroscopy, imaging techniques, X-ray and neutron-based methods, mechanical probing, and nuclear magnetic resonance spectroscopy. We specifically highlight the application of these techniques in elucidating ion transport dynamics, tracking redox processes, identifying degradation pathways, and detecting interphase formation. Furthermore, we discuss the limitations, challenges, and potential pitfalls associated with each method, as well as future directions for advancing characterization techniques to better understand and optimize 2D material-based electrodes
Comprehensive study of Mn/Ni ordering in LiNi0.5-xMn1.5+xO4 using neutron powder diffraction and scanning transmission electron microscopy
No full textInternational audienceIn this study, we extensively establish unique relationships between the chemical compositions of LiNi0.5-xMn1.5+xO4 (LNMO) spinel-type positive electrode materials and the degree of Mn/Ni ordering, which influences their electrochemical performance. To achieve this, in situ temperature-controlled neutron powder diffraction experiments were performed under air or oxygen atmospheres to track the Mn/Ni ordering process during annealing of LNMO samples that contain different Mn/Ni ratios. Systematic in-depth structural analysis of a large number of samples, using both neutron and synchrotron X-ray powder diffractions, revealed clear correlations between the variations in the voltage-composition profiles and the distribution of Mn and Ni atoms between the 4b and 12d crystallographic sites of ordered LNMO. Additionally, we employed high-resolution scanning transmission electron microscopy combined with fast Fourier transform analysis that enabled us to visualize the distribution and sizes of Mn/Ni ordered domains at the particle level in excellent agreement with the Rietveld refinement from neutron powder diffraction data
Fire Hazards of Carbonate-Based Electrolytes for Sodium-Ion Batteries: What Changes from Lithium-Ion Batteries?
No full textInternational audienceCarbonate-based electrolytes are often employed as the preferred electrolyte for both Li-ion and Na-ion cells. To investigate the fire risk during abuse conditions in real-life scenarios covering the full value chain, not only cell-level studies but also component-level investigation is crucial. Hence, Na-ion advanced electrolyte combustion tests are performed employing the fire propagation apparatus also called Tewarson calorimeter. Heat and combustion products releases are measured, making use of fire calorimetry laws and analytical techniques such as FTIR, NDIR, FID, or paramagnetic analyzers, and optical measurement. Thermal and chemical impacts of Na-ion electrolytes combustion and fires are assessed under well-ventilated and under-ventilated environments. Data are then compared against a carbonate-based electrolyte used in Li-ion batteries to create a comparative study between these technologies. Overall, the heat released rate majorly depends upon the solvents used and is less impacted by inorganic Li or Na salts while the emitted gases depend on both solvent and salt chemistry. Another key observation lies in the different fate of the fluorine element chemically bound to the concerned salts: in similar burning conditions, F from NaPF6 decomposition is preferably converted in F-containing solid species in the residues whilst LiPF6 gives off more gaseous species such as HF
High surface quality Y2SiO5 silicate-crystal waveguides etched by chlorine-based inductive coupled plasma reactive ion etching
No full textInternational audienceAmong rare-earth ion-doped crystals that are of high interest for quantum technologies, yttrium orthosilicate [Y2SiO5 (YSO)] crystal has demonstrated the longest coherence times. Etching optical guiding structures enables the creation of complex structures offering the advantage of technological scalability. We report on the dry etching of YSO crystal wafers performed by inductive coupled plasma (ICP) reactive ion etching. The material etching rate, the etch rate selectivity versus the material mask, and the etched side wall’s shape have been measured for various ICP process parameters and gas combinations including Ar-alone, Cl2:Ar, and Cl2:N2 plasma chemistry. These gas-combination choices have enabled identifying the etching mechanisms involved. Etching results have evidenced that Ar ions are the primary contributors for YSO etching, with Cl ions being also efficient, while Cl neutrals play a marginal role. ICP YSO etching is predominantly a physical process carried out by ions. Several ICP powers and RF powers have been investigated. The highest 80 nm/min etch rate is obtained under the Ar-alone plasma, but at the expense of trenching, while chlorine-based etching provides no trenching and smooth side walls. The choice of the dielectric material mask is also discussed
Structure and ion conducting properties of mixed-alkali Na<sub>3– x</sub>Li<sub> x</sub>InCl<sub>6</sub> solid electrolytes
No full textInternational audienceBall-milled and annealed Na3– xLi xInCl6 samples exhibit a solubility limit at x = 0.6 and a monoclinic-to-trigonal phase transition. Neutron diffraction and impedance spectroscopy suggest a connected Li network with enhanced ionic conductivity
Azide as a photolabile ligand in gold(I) therapeutics
No full textInternational audienceGold-based compounds are gaining attention as potential alternatives to platinum-based chemotherapeutics due to their high antiproliferative activity and unique mechanisms of action. However, challenges remain in enhancing their selectivity and reducing side effects. In this study, we synthesized and characterized a series of gold(I) azido complexes featuring phosphine and N-heterocyclic carbene ligands. Their cytotoxicity was assessed against human lung carcinoma (A549) and non-cancerous fibroblast (MRC-5) cells, revealing micromolar-range antiproliferative effects with varying selectivity. Additionally, their use as photoactivated chemotherapy (PACT) agents was explored, with some complexes displaying modulation of their cytotoxicity upon light exposure. These findings suggest that gold azido complexes could serve as promising drug candidates for chemotherapy treatments
Mechanosynthesis and Polymerization of Styrene Derivatives Based on Building Blocks of Lignin
No full textInternational audienceGiven the constraints dictated by the environment and the current policies, it is urgent to conceive and developnovel molecular building blocks and materials from bio-sourced platforms in order to compete and replace thoseobtained from petroleum sources (styrene, bisphenol A, etc.). Bio-sourced monomers can be obtained from thetransformation of molecules extracted from five main sources, namely terpenes, carbohydrates, lignin, proteins andlipids from animal, plant, or sea origin. Thanks to the presence of alcohol, acid or amine functional groups, thesebio-sourced molecules can often be polymerized by condensation reaction and yield bio-based polyesters orpolyamides with mechanical properties that can compete with their petroleum-based counterparts.Step-growth polymerization remains therefore the most explored pathway to produce bioplastics nowadays.Recently, the number of publications reporting free-radical chain-reaction polymerization (FRP) of bio-monomershas strongly increased. However, it remains still limited, probably due to the little number of readily availableradically polymerizable bio-sourced structures. In this context, lignin, the second most abundant natural polymericconstituent of wood, accounting for around 20% of the lignocellulosic biomass11 and currently discarded as wasteby the paper industry, appears to be a suitable candidate. Indeed, the controlled degradation of lignin allows toproduce biofuels, precursors for organic synthesis or oligomers that can be applied to prepare functional materials.Among those examples, the compounds obtained from lignin degradation represent a promising alternative todesign bio-sourced polymers displaying interesting thermo-mechanical properties thanks to the presence ofaromatic cycles.In this communication, we report the synthesis of polystyrenes prepared in three steps from vanillin, 4-hydrobenzaldehyde, and syringaldehyde, compounds that can be obtained through lignin depolymerization underoxidative conditions. The synthesis involves the conversion of these biosourced platforms into polymerizablestyrene derivatives through a methylation of the hydroxyl group followed by an olefination of the aldehyde function.The monomers were first synthesized under conventional conditions using solvents. Then, the synthesis wasimproved from the sustainability point of view by using a ball mill under solventless conditions, generating muchless waste in the process. Mechanochemistry has successfully been transposed from material sciences to organicchemistry in the past decades. Compared to conventional procedures and solvent-based reactions, it usesmechanical energy to induce a chemical reaction in solvent-free conditions and can afford shorter reaction times,higher yields and more sustainable process.The three monomers were then converted into biosourced homopolymers through free radical polymerization inbulk, providing functional polystyrene derivatives with thermal properties comparable to those of common petrosourced polystyrene
Polar Indirect Valley as a Limiting Factor for Radiative Efficiency in Gold-Based Mixed-Valence Double Perovskites
No full textInternational audienceDouble perovskites have emerged as promising alternatives to lead halide perovskites, aiming to mitigate challenges related to toxicity and chemical instability. Among them, mixed-valence gold halides such as Cs2Au+Au3+Cl6, which contain only a single type of metal cation in two oxidation states, stand out due to their unique structural and electronic properties. These materials exhibit strong absorption in the near-infrared range, making them attractive candidates for optoelectronic applications such as photovoltaics. In this work, we employ temperature-dependent optical spectroscopy techniques to demonstrate that these compounds exhibit particularly strong polar electron-phonon coupling, which has a profound impact on their optoelectronic properties. In particular, this coupling gives rise to a temperature-dependent absorption tail that reshapes the global spectral spectrum. We show that this tail leads to a forbidden band-egde recombination, which explains the reported difficulties in detecting a photoluminescence signal from this class of double perovskites
From plasma to quantum: the journey of nanodiamonds with color centers
No full textInternational audienceDiamond, a solid composed of carbon atoms, is an extremely interesting material for its technological and scientific applications, including those in nuclear physics and power electronics. Recent progress in controlling diamond synthesis has made it possible to produce very pure crystals and to incorporate and control atomic impurities and carbon vacancies in the crystal lattice. The appropriate impurity-vacancy combinations can give rise to special defects known as color centers, such as the nitrogen-vacancy (NV) or the silicon-vacancy (SiV), which exhibit exceptional quantum properties with spins that are optically addressable. The use of diamond containing color centers has paved the way for the development of innovative quantum technologies, such as very high-resolution magnetometry and quantum information processing [1-3]. Nevertheless, the development of quantum sensors at the nanometric scale remains one of the most interesting challenges. In this context, the development of a reliable nanoparticle synthesis technique that allows the desired defects to be incorporated and their quantum optical properties to be modulated is crucial. In this seminar, an efficient and recent method to produce diamond nanoparticles containing NV, SiV and germanium-vacancy (GeV) centers is proposed through direct plasma assisted chemical vapour deposition (CVD) growth [4, 5]. This technique allows good control of both nanoparticle growth processes and color centers formation. The optimization of the CVD nanodiamond growth process is presented, showing the impact of different plasma parameters and gas phase composition on nanoparticle crystallinity, size and shape. Morphological characterizations reveal the production of small (around 100 nm) and well faceted nanodiamond particles. In addition, the SiV and GeV color centers incorporation can be tuned within this material by varying the gas phase composition which emphasizes the high flexibility of the CVD growth technique. Finally, the quantum properties of the incorporated color centers have been successfully investigated under extreme pressure conditions (up to ~ 180 GPa) showing a monotonic blue shift of their optical zero-phonon line. Since their luminescence remains stable, SiV and GeV centers emerge as high-pressure nanosensors [6]. References[1] G. Villaret, L. Mayer, M. Schmidt, S. Magaletti, M. De Feudis, M. Markham, A. Edmonds, J.-F. Roch, T. Debuisschert, Applied Physics Letters 122, 194001 (2023).[2] A. Hilberer, L. Toraille, C. Dailledouze, M.-P. Adam, L. Hanlon, G. Weck, M. Schmidt, P. Loubeyre, J.-F. Roch, Physical Review B 107, L220102 (2023).[3] M. Pompili, S. L. N. Hermans, S. Baier, H. K. C. Beukers, P. C. Humphreys, R. N. Schouten, R. F. L. Vermeulen, M. J. Tiggelman, L. dos Santos Martins, B. Dirkse, S. Wehner, R. Hanson, Science 372, 259–264 (2021).[4] M. De Feudis, A. Tallaire, L. Nicolas, O. Brinza, P. Goldner, G. Hétet, F. Bénédic, J. Achard, Advanced Materials Interfaces 7, 1901408 (2019).[5] A. Tallaire, O. Brinza, M. De Feudis, A. Ferrier, N. Touati, L. Binet, L. Nicolas, T. Delord, G. Hétet, T. Herzig, S. Pezzagna, P. Goldner, J. Achard, ACS Applied Nano Materials 2, 5952 (2019).[6] B. Vindolet, M.-P. Adam , L. Toraille, M. Chipaux, A. Hilberer, G. Dupuy, L. Razinkovas, A. Alkauskas, G. Thiering, A. Gali, M. De Feudis, M. W. Ngandeu Ngambou, J. Achard, A. Tallaire, M. Schmidt, C. Becher, J.-F. Roch, Physical Review B 106, 214109 (2022)
Sub-MHz homogeneous linewidth in epitaxial Y 2 O 3 : Eu 3+ thin film on silicon
No full textInternational audienceAbstract Thin films provide nanoscale confinement together with compatibility with photonic and microwave architectures, making them ideal candidates for chip-scale quantum devices. In this work, we propose a thin film fabrication approach yielding the epitaxial growth of Eu 3+ doped Y 2 O 3 on silicon. We combine two of the most prominent thin film deposition techniques: chemical vapor deposition (CVD) and molecular beam epitaxy (MBE). We report sub-megahertz optical homogeneous linewidths up to 8 K for the Eu 3+ dopants in the film, and lowest value of 270 kHz. This result constitutes a ten-fold improvement with respect to previous reports on the same material, opening promising perspectives for the development of scalable and compact quantum devices containing rare-earth ions