Portail HAL ENSCP
Not a member yet
9647 research outputs found
Sort by
Addressing Bottlenecks to Achieve High-Energy Sodium-Ion Cells Using Tin Anodes or Anode-Free
No full textInternational audienceSodium-ion batteries (NIBs), as a complementary energy storage device for Li-ion batteries, are swiftly making their way into high-power applications market. However, further progress in NIBs requires high energy density. This necessitates shifting from the commonly used hard carbon (HC) anodes to alloy anodes such as Bi/Sn/Sb, etc., while overcoming the problems these materials pose with regard to volume changes and interfacial reactivity. This article focuses on issues related to the chemistry of Na3V2(PO4)2F3 (NVPF)|Sn-HC based cells using 1M NaPF6 in diglyme as electrolyte and proposes solutions. Through operando, ex-situ, and post-mortem (electro)chemical characterizations, we demonstrate that glyme electrolytes remain stable under reduction. However, their low oxidative stability gives rise to parasitic species that interfere with and poison the Sn-HC electrode. This results in poor cycling stability, preventing their use in Naion cells. To mitigate this problem, we propose various solutions, such as (i) using a low-voltage cathode, (ii) coating Sn with a protective layer, and (iii) introducing chemical traps such as Nametal, Na15Sn4, or NaxC between the separators. Of all these solutions, the traps are the most effective, completely suppressing cross-talk poisoning, enabling 100% capacity retention of NVPF|Sn-HC cells over 200 cycles at C/5. Furthermore, we demonstrate that this concept can be extended to anode-free configurations, achieving 91% capacity retention after 80 cycles at C/10. This presents a practical design principle for Na-ion cells with energy densities approaching those of Li-ion systems, and can be adapted to other chemistries susceptible to cross-talk poisoning
Na2Fe3(SO4)4: a zero-strain sustainable positive electrode material for Na-Ion batteries
No full textInternational audienceOne of the challenges in the energy transition is minimization of the battery cost for energy grid storage. Na-ion batteries are a promising alternative to Li-based analogues thanks to low cost, abundance of constituents, and an already set-up industry. However, already commercialized positive electrode materials for Na-ion batteries (Na3V2(PO4)2F3 and NaxCu1-y-zFeyMnzO2) contain critical raw elements such as V, Cu, and Mn, boosting the research towards abundant Fe-based materials. In this work, we report a novel sodium iron sulfate phase, Na2Fe3(SO4)4 (NFS), synthesized by ball milling, as a positive electrode material. This new compound crystallizes in the orthorhombic Pbca space group with cell parameters a = 9.682(1) Å, b = 8.739(1) Å, c = 29.300(4) Å, and V = 2479.0(5) Å3. Tests of thick NFS positive electrodes (18 mg cm−2) in Na-half coin cells delivered 62 mAh g−1 at C/30 (corresponding to the exchange of 2 e-) or 69% of the theoretical capacity (90 mAh g−1), with a good capacity retention of 47 mAh g−1 at a high discharge rate 2C. Operando X-ray diffraction (XRD) showed minimal (<1%) changes in lattice parameters during cycling. Dominantly octahedra coordinated iron atoms are oxidized/reduced, as confirmed by operando synchrotron Mössbauer spectroscopy.</p
Enabling Structural and Electrochemical Stability of 2D Antimonene for Potassium-Ion Storage with Nonflammable Electrolyte
No full textInternational audienceAlloy-type anodes with high theoretical capacities and low working potentials are promising candidates for use in rechargeable batteries. However, their development faces significant challenges due to active material pulverization associated with large volume expansion and an unstable solid electrolyte interphase (SEI) formed with conventional electrolytes. In this study, we report a two-dimensional (2D) metallene, 2D antimonene, as anode material combined with nonflammable 1 M triethyl phosphate (TEP) and tris(2,2,2-trifluoroethyl) phosphate (TFP)-based electrolytes, achieving structural and electrochemical stability for potassium-ion storage. We disclose that the 2D antimonene develops a wrinkled morphology while retaining its structural integrity without cracking after cycling, highlighting its effectiveness in accommodating stress from large volume change. Meanwhile, TEP-based electrolyte accelerates the formation of stable anion-derived SEI, and TFP-based electrolyte produces a KF-rich SEI, effectively passivating the electrochemical interface and preventing electrolyte depletion. In potassium-ion batteries (PIBs), 2D antimonene delivers stable capacities of 486.8/492.6 mAh g–1 with retention of 94.6/91.4% over 200 cycles in nonflammable TEP and TFP-based electrolytes, respectively. Impressively, it obtains superior rate performance and long-term stability, maintaining a capacity of 312.3 mAh g–1 over 400 cycles at 0.5 A g–1 in the TEP system. Furthermore, the full cell was successfully demonstrated at temperatures of 50 and −20 °C. This work advances the development of 2D metallenes with nonflammable electrolytes, enabling the application of high-performance alloy-type anodes for safe PIBs
Deciphering the Effects of Plasmonic Nanoparticles Doping in Hybrid Perovskite Photovoltaic and Photodetector Devices
No full textInternational audienceObtaining high‐performance films of organo‐metallic halide perovskites is still a challenging task, with tremendous potential outcomes for devices involving light absorption such as next‐generation photovoltaics or photodetectors. In many experimental reports, particularly on perovskite solar cells, the addition of metallic nanoparticles (gold, silver…) has demonstrated promising performance improvements. However, while light management strategies based on plasmonic resonances are the initial motivation for these experiments, various other explanations have been proposed and the plasmonic nature of the performance boost is not always clear. In this article, optical simulation analysis is combined with a general review of the experimental reports to elucidate the role of nanoparticles in perovskite devices from a multifaceted perspective. Performance improvements were recently reported for various devices (solar cells, photodetectors) of different perovskite materials where gold nanoparticles were introduced either by spin coating or evaporation. Alongside a comprehensive examination of conventional optical effects, a novel function is identified of nanoparticles in regulating the crystallization rate of perovskite films, leading to enhanced film quality and ultimately boosting light absorption and device optical performance. This analysis enriches the mechanistic understanding for future studies on the use of nanoparticles in perovskite‐based devices, offering a novel approach for optimizing perovskite films
Erbium doped yttrium oxide thin films grown by chemical vapour deposition for quantum technologies
No full textInternational audienceThe obtention of quantum-grade rare-earth doped oxide thin films that can be integrated with optical cavities and microwave resonators is of great interest for the development of scalable quantum devices. Among the different growth methods, Chemical Vapour Deposition (CVD) offers high flexibility and has demonstrated the ability to produce oxide films hosting rare-earth ions with narrow linewidths. However, growing epitaxial films directly on silicon is challenging by CVD due to a native amorphous oxide layer formation at the interface. In this manuscript, we investigate the CVD growth of erbium-doped yttrium oxide (Er:Y2O3) thin films on different substrates, including silicon, sapphire, quartz or yttria stabilized zirconia (YSZ). Alternatively, growth was also attempted on an epitaxial Y2O3 template layer on Si (111) prepared by molecular beam epitaxy (MBE) in order to circumvent the issue of the amorphous interlayer. We found that the substrate impacts the film morphology and the crystalline orientations, with different textures observed for the CVD film on the MBEoxide/Si template (111) and epitaxial growth on YSZ (001). In terms of optical properties, Er 3+ ions exhibit visible and IR emission features that are comparable for all samples, indicating a high-quality local crystalline environment regardless of the substrate. Our approach opens interesting prospects to integrate such films into scalable devices for optical quantum technologies
Impact of Graphite Properties and Electrode Formulation on Potassium-Ion Battery Performance and Storage Mechanisms
No full textInternational audienc
Direct assembly of micrometer-long polymeric cylinders in water via supramolecular sticker engineering
No full textInternational audienceWe report a direct, solvent-free method to produce micrometer-length, well-organized polymer nanocylinders in water. To achieve this, a hydrophilic poly(N,N-dimethylacrylamide) (PMDAc) was functionalized at one chain-end with a perylene diimide (PDI) sticker using RAFT polymerization. Two PDI RAFT agents were prepared and studied: one featuring two tri(ethylene glycol) (TEG) units at the PDI bay-positions and one without. The corresponding PDI-PDMAc conjugates spontaneously self-assemble in water, driven by π-π interactions made of H-aggregates, and show a morphological evolution from cylinders to spheres when increasing the polymer chain length. The introduction of TEG units was found to be important to avoid the clustering of nanocylinders or the formation of ill-defined assemblies, which were observed in the TEG-free system. Moreover, we found that the PDI-TEG 2 -PDMAc with degrees of polymerization (DP n ) below 24 self-assembled into micrometer-long nanocylinders. By heating the aqueous polymer solution, this process can be accelerated and is accompanied by a large increase in viscosity. Fluorescence spectroscopy revealed an excimer emission signal for the PDI polymers in water, with a higher emission for cylinders, suggesting better organization within the PDI H-aggregates. This strategy provides a sustainable approach for developing functional nanomaterials with precise morphological control, eliminating organic solvents and complex processing
3D Resolved Computational Modeling to Simulate the Electrolyte Wetting of a Lithium‐Ion Battery Cell with 18650 Format
No full textInternational audienceElectrolyte wetting in a lithium‐ion battery (LIB) cell is a time‐intensive and quality‐critical manufacturing step that determines the degree of homogeneity of lithium ion's transport within the electrode and separator pores, affecting the overall ionic conductivity and current density. If the electrolyte is inadequately distributed, it can compromise the cell performance. In this work, we introduce a novel engineering‐oriented model to simulate electrolyte wetting in a LiNi 0.33 Mn 0.33 Co 0.33 O 2 –graphite 18650 cylindrical LIB cell. Governing equations are supported on a pressure‐saturation formulation incorporating Darcy's law and phase‐transport expressions, solved through the finite element method in COMSOL Multiphysics. The model is parameterized with experimental data extracted from literature, and free parameters are optimized via a sensitivity analysis to maximize wetting. Results indicate that saturation is predominantly controlled by the capillary pressure and the spatial electrolyte distribution across the different functional layers of the jelly roll (electrodes and separator). The obtained electrolyte saturation of 86% is consistent with saturation values reported in literature obtained with different methodologies. Our 3D‐resolved modeling approach uniquely captures how 18650 cell spiral geometry and component properties influence electrolyte distribution and, to the best of our knowledge, it is the first capable to simulate wetting behavior in a full‐scale cylindrical LIB cell
Understanding the Role of Oxygen Substitution in Lithium Conduction and Air/Interfacial Stability of LGPS-Structured Oxy-Sulfide Electrolytes
No full textInternational audienceThe development of stable and high-performance solid electrolytes is critical for the commercialization of solid-state batteries (SSBs). This study explores materials with the composition Li9.6P3S12-kOk (0 ≤ k ≤ 1.0) by partially substituting sulfur with oxygen in Li9.6P3S12 to enhance electrochemical and ambient stability while maintaining high ionic conductivity. The synthesized compounds Li9.6P3S11.1O0.9 Li9.6P3S10.5O1.5, and Li9.6P3S9.9O2.1 having 7.5%, 12.5% and 17.5% oxygen content, named as LPSO-7.5, LPSO-12.5, and LPSO-17.5, exhibit an LGPStype structure with reduced secondary phases compared to previous studies. The highest ionic conductivity of 0.75 mS cm -1 was observed for LPSO-7.5 at 510 MPa, while increased oxygen content led to lower conductivity due to structural distortions and reduced lithium-ion mobility.Electrochemical impedance spectroscopy (EIS) and symmetric Li/SE/Li cells confirmed improved electrochemical performance with lithium metal for LPSO-7.5. Full-cell tests with LiNi0.8Co0.15Al0.05O2 (NCA) cathode and graphite or lithium anodes showed that LPSO-7.5 demonstrated the highest capacity retention and the lowest polarization. Additionally, H2S gas evolution tests confirmed improved air stability with increasing oxygen content. The results indicate that moderate oxygen substitution optimally balances conductivity, air stability and interfacial compatibility. LPSO-7.5 emerges as a promising solid electrolyte candidate for nextgeneration SSBs with enhanced cycle life and reduced degradation.</p
Rhodium-catalyzed enantioselective transfer hydrogenation of a-chloro b-ketophosphonates via dynamic kinetic resolution
No full textInternational audienceA rhodium-catalyzed asymmetric transfer hydrogenation (ATH) of alpha-chloro beta-ketophosphonates via dynamic kinetic resolution (DKR) has been developed. A wide range of syn alpha-chloro beta-hydroxy-phosphonates were efficiently synthesized with high yields and excellent enantio- and diastereoselectivities (up to 99% ee and > 99 : 1 dr) under mild reaction conditions. A gram-scale experiment was conducted successfully, which offers a straightforward approach to a key intermediate of fosfomycin