Doping is a widely employed technique to enhance the functionality of lithium-ion battery materials, tailoring their performance for specific applications. In our study, we employed in situ Raman and ...in situ X-ray diffraction (XRD) spectroscopic techniques to examine the structural alterations and electrochemical behavior of phosphorus-doped titanium dioxide (TiO2) nanoparticles. This investigation revealed several notable changes: an increase in structural defects, enhanced ionic and electronic conductivity, and a reduction in crystallite size. These alterations facilitated higher lithiation rates and led to the first observed appearance of LiTiO2 in the Raman spectra due to anatase lithiation, resulting in a reversible double-phase transition during the charging and discharging processes. Furthermore, doping with 2, 5, and 10 wt % phosphorus resulted in an initial increase in specific capacity compared to undoped TiO2. However, higher doping levels were associated with diminished capacity retention, pinpointing an optimal doping level for phosphorus. These results underscore the critical role of in situ characterization techniques in understanding doping effects, thereby advancing the performance of anode materials, particularly TiO2, in lithium-ion batteries.
In advancing sodium-ion battery technology, we introduce a novel application of Na3NiZr(PO4)3 with a NASICON structure as an anode material. This research unveils, for the first time, its exceptional ...ability to maintain high specific capacity and unprecedented cycle stability under extreme current densities up to 1000 mA·g−1, within a low voltage window of 0.01–2.5 V. The core of our findings lies in the material’s remarkable capacity retention and stability, which is a leap forward in addressing long-standing challenges in energy storage. Through cutting-edge in situ/operando X-ray diffraction analysis, we provide a perspective on the structural evolution of Na3NiZr(PO4)3 during operation, offering deep insights into the mechanisms that underpin its superior performance.
Abstract
Chiastolite-type andalusite, whose genesis occurred in the currently unexploited deposit of Sidi Bou Othman (Morocco), has been extensively characterized. The phase composition, ...microstructure, thermal behavior, sinterability, and evolution of the crystallographic structure associated with the transformation of andalusite to mullite were accurately analyzed. Parallelepiped-shaped crystal grains exhibited off-white X crosses, typical of the chiastolite group. The chemical composition is closely dependent on the crystal size and proportion of alumina. The crystal structure was successfully refined using XRD, and chemical analysis was performed for different crystal sizes up to 30 mm. Powder compacts were prepared from these chiastolites for further characterization after various thermal treatments. According to the Rietveld refinement analysis, the mullization ranges from 1200 to about 1500 °C, and crystallographic parameters have been compared with other andalusites reported in literature. In agreement with this phase transformation, variations related to different material properties such as thermal expansion, pore volume fraction, and mechanical strength were evaluated. These results highlight the potential for further exploitation of the Sidi Bou Othman deposit to produce refractory materials.
In the present work, Moroccon Tarfaya oil shale was treated by acids and different solvents under supercritical conditions, successively. Experimental results showed clearly that residual mineral ...matter had a significant effect on the yield and composition of the resulting organic fraction. Indeed, the oil yields obtained from some samples, 43% and 56%, respectively, were much higher than that from the sub-layer, 18%. In addition, the yield of recuperation and quality of extracted oils were largely dependent on the nature of solvents (toluene, water, shale oil). Thus, phenol was shown to be a very efficient modifier for the supercritical extraction of organic matter from Tarfaya oil shale with toluene, affording a good yield of recovery and a suitable maturation of organic matter. The pitches prepared by mixing phenol and toluene contained more aromatics and had a high char yield (46%) at 950 degreesC compared to those obtained by extraction with supercritical toluene alone. Keywords: Tarfaya oil shale, mineral matter, supercritical extraction, water, toluene, phenol.
Metallic Zn is a preferred anode material for rechargeable aqueous batteries towards a smart grid and renewable energy storage. Understanding how the metal nucleates and grows at the aqueous Zn anode ...is a critical and challenging step to achieve full reversibility of Zn battery chemistry, especially under fast‐charging conditions. Here, by combining in situ optical imaging and theoretical modeling, we uncover the critical parameters governing the electrodeposition stability of the metallic Zn electrode, that is, the competition among crystallographic thermodynamics, kinetics, and Zn2+‐ion diffusion. Moreover, steady‐state Zn metal plating/stripping with Coulombic efficiency above 99 % is achieved at 10–100 mA cm−2 in a reasonably high concentration (3 M) ZnSO4 electrolyte. Significantly, a long‐term cycling‐stable Zn metal electrode is realized with a depth of discharge of 66.7 % under 50 mA cm−2 in both Zn||Zn symmetrical cells and MnO2||Zn full cells.
Ultrafast metal electrodeposition in fast‐charging Zn batteries was investigated by in situ optical imaging and theoretical modeling. The critical parameters governing the electrodeposition stability of the metallic Zn electrode were uncovered, guided by which a highly reversible Zn metal electrode in an aqueous battery with a depth of discharge of 66.7 % at 50 mA cm−2 was achieved.
Tunnel‐structured MnO2 represents open‐framed electrode materials for reversible energy storage. Its wide application is limited by its poor cycling stability, whose structural origin is unclear. We ...tracked the structure evolution of β‐MnO2 upon Li+ ion insertion/extraction by combining advanced in situ diagnostic tools at both electrode level (synchrotron X‐ray scattering) and single‐particle level (transmission electron microscopy). The instability is found to originate from a partially reversible phase transition between β‐MnO2 and orthorhombic LiMnO2 upon lithiation, causing cycling capacity decay. Moreover, the MnO2/LiMnO2 interface exhibits multiple arrow‐headed disordered regions, which severely chop into the host and undermine its structural integrity. Our findings could account for the cycling instability of tunnel‐structured materials, based on which future strategies should focus on tuning the charge transport kinetics toward performance enhancement.
The lithiation front region of one β‐MnO2 nanowire analyzed by in situ TEM, where the MnO2/LiMnO2 interface features arrow‐headed disordered regions, is disclosed with its atomic structure clearly captured. The findings have a bearing on MnO2 open‐framed electrode materials for reversible energy storage.
Obtaining cathode materials with high capacity and cycle stability is one of the main challenges regarding the success of electric vehicle technologies. However, most of the widely used materials ...with these properties involve the use of toxic and expensive cobalt as the active material. To overcome this challenge, this work proposes a novel cobalt-free cathode material, synthesized for the first time using a solid-state reaction, whose general formula is LiNi0.8Fe0.1Al0.1O2 (NFA). This class of materials offers high capacity and reduces the battery costs by removing cobalt, without jeopardizing the structural stability and safety of the NFAs. The morphology and the structural properties of the obtained NFA cathode material were characterized using different techniques, e.g., scanning electronic microscopy, X-ray diffraction, X-ray fluorescence, and infrared and Raman spectroscopies. The electrochemical activity and diffusivity of the Li-ion during lithium removal and its insertion into the bulk of the NFA cathode demonstrated high-yield specific capacities of ≈180 mAh g−1 at 0.1C, along with a reasonable rate capability and cycling stability, with a capacity retention of ≈99.6% after 100 charge/discharge cycles at a rate of C/2, and whose operando X-ray diffraction experiments have been used to study the crystallographic transitions during the lithiation–delithiation reaction.
•The effect of alloying on the properties of hard coatings is reviewed.•The influence of coating architecture on the performance of hard coatings is reported.•HiPIMS coatings exhibits superior ...mechanical properties compared to dcMS.
Hard coatings are extensively used in various industries, including automotive, aerospace and tooling industries. Hard coatings are deposited using, typically, chemical vapor deposition (CVD) and physical vapor deposition (PVD) techniques. Among these, magnetron sputtering (MS) is widely used to deposit hard transition metal nitrides and oxides. In the last 20 years, technological development gave birth to a highly ionized magnetron sputtering technique called High Power Impulse Magnetron Sputtering (HiPIMS) that allows application tailored coating development.
The present article reviews studies on the deposition of hard coatings by HiPIMS and direct current MS (dcMS). The effect of alloying and coating architecture design on mechanical properties is highlighted, and comparative studies highlighting the difference between the two techniques are reviewed, while the effect of different HiPIMS deposition parameters on the mechanical properties of the coatings is presented and discussed.
Titanium carbide (TiC) coatings are widely used in several industrial applications, including tooling and tribological applications. These materials are used due to their mechanical, tribological and ...wear resistance properties, and chemical inertness. Hard TiC coatings are conventionally deposited using chemical vapor deposition techniques at temperatures in the range of 1000 °C, which limits its application to temperature sensitive substrate materials. Therefore, plasma enhanced chemical vapor deposition has been utilized as an alternative deposition technique, showing good coating performance at temperatures as low as 500 °C. Recent technology developments have seen the emergence of high-power impulse magnetron sputtering (HiPIMS) as a promising approach to deposit high quality TiC coatings at ambient temperatures, thus making the use of new substrate materials and new applications possible.
The present article introduces magnetron sputtered TiC-based coatings with an emphasis on their structural, mechanical and tribological properties. An overview of the most relevant technological approaches for the development of binary and ternary TiC-based coatings over recent decades is presented. The relationship between the deposition parameters and the final coating properties is highlighted and discussed. Steering towards ternary TiC-based system have shown to improve the coating properties. In this light, several chemical elements have been used resulting in the formation of various coating structures including metastable solid solution, binary and/or ternary phases, or mixtures thereof. The benefit of adding a third element is discussed and its impact on the coating properties is highlighted. Finally, new outlook for potential applications is presented.
•Summary of titanium carbide-based films mechanical and tribological properties.•Properties of ternary Ti-X-C.•Deposition process-to-coating properties relationship.•Impact of high flux-low energy deposition process such as HiPIMS on TiC-based films.•Future research directions and applications are highlighted.
The quality of coatings deposited by magnetron sputtering is known to depend on, among others, the magnetic field strength (Φ) and the magnetic field configuration. Furthermore, high power impulse ...magnetron sputtering (HiPIMS) is known to result in low defect - high density coatings, and is therefore used to deposit barrier coatings against wear and corrosion. The influence of varying the Φ, on deposition rate (R), structure and hardness of titanium nitride coatings prepared by HiPIMS and dc magnetron sputtering (dcMS) was investigated. At 22mT, the ratio between HiPIMS deposition rate and dcMS deposition rate (RHiPIMS/RdcMS) was almost equal to 1. As Φ was increased from 22mT to 35mT, R decreased by 28% for HiPIMS and increased by 15.6% for dcMS, and RHiPIMS/RdcMS was reduced from 1 to 0.63. From 35mT to 44mT, the decrease in R slowed to 6% for HiPIMS and to 12.5% for dcMS. The (111) orientation was dominant over (200) orientation for both HiPIMS and dcMS, and become less dominant with the Φ in the case of dcMS. The residual stresses and surface roughness were determined and their evolution with Φ is highlighted. Mechanical characterization of the deposited coatings was performed, where the hardness tests showed that on average the HiPIMS coatings (29-34GPa) were some 5 GPa harder than dcMS coatings (25-27GPa).
•TiN films were deposited using HiPIMS and dcMS technologies.•The effect of magnetic field strength on structure, hardness and deposition rate of TiN coatings was studied.•TiN coatings obtained using HIPIMS have shown a higher hardness than those obtained using dcMS..•The hardness did not show a noticeable change with the magnetic field strength in the range studied 22-44mT.
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