Freeze-dried WS2 composites with low content of graphene as high-rate lithium storage materials

Few layered WS2-graphene nanosheet composites are prepared by a simple and scalable hydrothermal reaction and a subsequent freeze-drying method. The freeze-dried WS2-graphene composite exhibits good cycling stability and outstanding high-rate capability of lithium storage. The reversible capacity remains 647 mA h g-1 after 80 cycles at a current density of 0.35 A g-1. Comparable capacities of 541 and 296 mA h g-1 can still be maintained when cycling at even higher current densities of 7 and 14 A g-1 (7 and 14 mA cm-2) respectively.close10

Effect of the Heat Treatment on the Lithium Insertion Process in MoO₃

AbstractWe have studied the electrochemical characteristics of Li/MoO3-based batteries in relation with the morphology of the cathode-active material. The oxides and oxide-hydrates of molybdenum have been prepared with various degrees of heat treatement. The samples were characterized by X-ray diffraction, Raman spectroscopy, and conductivity measurements. The effect of the heat treatment on structural, optical and electrochemical properties are presented in this work. Thermodynamics and kinetics of lithium insertion were studied in MoO3 cathodes. Diffusion coefficients and enhancement factors were calculated as functions of the degree of lithium intercalation in the domain of the galvanic cell reversibility.</jats:p

L’assurance de transport maritime de commerce extérieure en Algérie Cas : CAAT Alger

75 p.:ill;30cm.(+cd)Le transport maritime est le moteur du commerce international et représente environ 90% des échanges mondiaux de marchandises. Ce mode de transport est caractérisé par le chargement et déchargement des conteneurs dans les ports, offrant une solution économique efficace pour déplacer de grandes quantités de marchandises sur de longues distances avec des coûts compétitifs. Par ailleurs, l’assurance maritime joue un rôle crucial en protégeant les marchandises contre les pertes et dommages durant le transport, ce qui rassure les commerçants et favorise les investissements .Ce cadre sécuritaire a contribué à la prospérité du commerce international. L’étude que nous avons menée au niveau de la compagnie Algérienne d’assurance Total CAAT, nous a permis de comprendre comment s’effectue les procédures d’un contrat d’assurance dans le commerce international , mais aussi comment s’effectue a l’indemnisation d’un cas de sinistre. Cela a été notifié dans ce contrat entre SAIDAL et la CAAT dans le cas d’importation d’une matière première

Contribution à l’étude des ectoparasites et des endoparasites du Goéland leucophée Larusmichahellis (Naumann, 1840) au niveau de la région de Boumerdès (Corso)

86 p. : ill. ; 30 cm. (+ CD-Rom)L’étude de l’inventaire des ectoparasites et des endoparasites du Goèland leucophèe dans la région de Boumerdès a été réalisée sur une période de 5 mois allant de Février jusqu’au Juin 2022. Nous avons mesuré les paramètres morphologiques des quatre oiseaux (Poids, Longueur, Taille Envergure, Longueur du Tarse, Longueur du Bec). Les résultats obtenus par l’identification des ectoparasites indique les Goélands sont infectés par trois espèces d’acariens: Zachvatkinia larica, Alloptes oxylobus, Dermanyssus gallinae et quatre espèces d’insectes: Quadraceps penctatus, Actornithophilus piceus lari, Austromenopon transversum et Xenopsylla cheopis. Ils sont également infectés par trois espèces d'endoparasites : Trichostrongylus spp, Syngamus sp et Capillaria sp

Electrochemical Feature of Hydrated Molybdenum Oxides in Lithium Batteries

ABSTRACTOxide-hydrates of molybdenum [OHM] are investigated as 3-volt cathode materials for rechargeable lithium batteries. The oxides and oxide-hydrates of molybdenum have been prepared at various degrees of heat treatment. The oxide-hydrates of molybdenum with different water content showed a much better performance as cathode of the rechargeable lithium battery than that of MoO3. From these results, it was found that the crystalline-bonded water molecules play an important role for the high discharge capacity and high cyclability. We report the electrochemical characteristics of Li/OHM batteries using the oxides and oxide-hydrates of molybdenum which have been prepared with various degrees of heat treatment of molybdic acid. The oxide has a corrugated layer structure consisting of corner-shared MoO6octahedra. This structure provide electronic conductivity within a layer and high lithium ion mobility between layers. The mechanism of dehydration and structural rearrangement of molybdic acid during heat treatment were studies by thermal analysis, X-ray diffraction, Raman and infrared spectroscopy. Thermal analysis indicates a two-step dehydration and formation of orthorhombic α-MoO3and monoclinic β-MoO3. Discharge profiles and kinetics of the materials are dependent on the amount of “structural water” into the host lattice. The electro-insertion of Li ions occurs mainly in two steps in the potential range between 3.0 and 1.5 V (compositional range 0&lt;xLi&lt;l.5). Kinetic measurement show that Li ions are highly mobile in the OHM framework. The partial molar quantities δGx, δSx, and δHx, estimated from EMF-temperature measurements and coulometric titration.</jats:p

Molybdenum and Vanadium Oxide Polycrystalline Films: Properties and Application to Lithium Microbatteries

ABSTRACTWe report on the growth of molybdenum and vanadium oxide films, i.e., MOO3, V205, and V6013, and their application as positive electrodes in lithium microbatteries. We have characterized various polycrystalline samples and studied how their structural and electrical properties are affected by the different preparation conditions. The highest quality films were grown on silicon substrate maintained at 250°C and annealed at 300°C. It is shown that the growth conditions play an important role in the electrochemical properties of the film. Both thermodynamic and kinetic parameters are strongly dependent on film morphology and stoichiometry. Microbatteries fabricated with cathodes formed at moderate temperature have shown a volumetric capacity about 80 μAh/μm/cm2. The cells exhibit a monotonous discharge profile indicating that the cathode materials remain single phase even for a large degree of intercalation.</jats:p