Fluorinated reduced graphene oxide as a protective layer on the metallic lithium for application in the high energy batteries

International audienceMetallic lithium is considered to be one of the most promising anode materials since it offers high volumetric and gravimetric energy densities when combined with high-voltage or high-capacity cathodes. However, the main impediment to the practical applications of metallic lithium is its unstable solid electrolyte interface (SEI), which results in constant lithium consumption for the formation of fresh SEI, together with lithium dendritic growth during electrochemical cycling. Here we present the electrochemical performance of a fluorinated reduced graphene oxide interlayer (FGI) on the metallic lithium surface, tested in lithium symmetrical cells and in combination with two different cathode materials. The FGI on the metallic lithium exhibit two roles, firstly it acts as a Li-ion conductive layer and electronic insulator and secondly, it effectively suppresses the formation of high surface area lithium (HSAL). An enhanced electrochemical performance of the full cell battery system with two different types of cathodes was shown in the carbonate or in the ether based electrolytes. The presented results indicate a potential application in future secondary Li-metal batteries

The Role of Cellulose Based Separator in Lithium Sulfur Batteries

International audienceIn this work, abundant and environmentally friendly nano-fibrillated (NFC) cellulose is used for fabrication of porous separator membranes according to the procedure adopted from papermaking industry. As-prepared NFC separators were characterized in terms of thickness, porosity, wettability, electrochemical stability and electrochemical performance in lithium-sulfur and Li-symmetrical pouch cells and compared to a commercial Celgard 2320 separator membrane. Results demonstrated that morphology and electrochemical performance of NFC separator outperforms the conventional polyolefin separator. Due to exceptional interplay between lithium metal and cellulose, this research provides a self-standing NFC separator that can be used besides the lithium-sulfur also in other lithium metal battery configurations

DEVELOPMENT OF MOULDED PULP PROTECTIVE PACKAGING FROM ALTERNATIVE FIBERS

<p>Expanded polystyrene foam is a standard protection element for many packaging solutions which needs cushioning properties against mechanical stresses. While its protective functions are very good (lightweight good cushioning properties, easy to 3D-form with tooling) the environmental aspect of this material is questionable due to bulkiness (high space volume) and low rates of real and viable recycling infrastructure. Due to that producers have switched to fiber solutions (corrugated board inserts, fiber foams and biopolymer fiber composites) as an alternative solution. Even though this fiber-based alternative solutions are environmentally friendlier the overuse of cellulose fibers from wood sources can also be a burden on the environment. On the other hand, invasive alien plants due to their negative impact on biodiversity and other economic damage (riverbank degradation) are one of the possible solutions for producing fiber elements.</p><p>In this paper the development of moulded fiber cushioning elements, made from locally sourced invasive fiber alien plants (Japanese knotweed and Canadian goldenrod) and processed in Slovenia is presented as a part of the protective packaging system for household appliances. The fiber morphology and processing as well the prototyping of the moulding tools have influenced the mechanical properties needed for protection simulation due to different fiber bonding and entanglement. The obtained results serve as a basis for further development and structural analysis (finite elements modelling) of stress points for building simulation software for the use of alternative fiber solutions.</p&gt

Effects of a mixed O/F ligand in the Tavorite-type LiVPO[sub]4O structure

We report the synthesis and detailed structuraland chemical characterization including electrochemicalproperties of a lithium vanadium oxy/fluoro-phosphatematerial. To the best of our knowledge, we have for the firsttime synthesized a LiVPO4O-type phase with a mixed O/Fligand. In the synthesis procedure, the LiVPO4O precursorcompound was fluorinated via LiF incorporation, withpreservation of the LiVPO4O framework structure. Theoperating potential of the synthesized material is increasedcompared to that of the LiVPO4O precursor (4.12 V vs 3.95 Vversus metallic lithium, respectively). The related increase inoperating potential was assigned to the effect of theintermixing O/F ligand, which is attained via the successfulfluorine incorporation into the LiVPO4O structure. A characterization of the investigated materials was performed usingmicroscale-covering XRD, XANES, and NMR techniques as well as nanoscale spatially resolved imaging and analytical STEMtechniques. The obtained oxy/fluoro-phosphate phase is isostructural to LiVPO4O; however, the presence of the mixed O/Fligand promoted a higher symmetry of vanadium octahedra. These variations of the vanadium local environment along with theobserved inhomogeneous distribution of the incorporated fluorine gave rise to the minor local deviations in vanadium valence.Our results clearly emphasize the connection among the fluorine ligand incorporation, its local distribution, and theelectrochemical properties of the material

Magnetic Properties of SmCo5 + 10 wt% Fe Exchange-Coupled Nanocomposites Produced from Recycled SmCo5

Nanostructured alloy powders of SmCo5 + 10 wt% Fe obtained using recycled material were studied for the first time. The SmCo5 precursor was obtained from commercial magnets recycled by hydrogen decrepitation. The results were compared with identically processed samples obtained using virgin SmCo5 raw material. The samples were synthesized by dry high-energy ball-milling and subsequent heat treatment. Robust soft/hard exchange coupling was observed—with large coercivity, which is essential for commercial permanent magnets. The obtained energy products for the recycled material fall between 80% and 95% of those obtained when using virgin SmCo5, depending on milling and annealing times. These results further offer viability of recycling and sustainability in production. These powders and processes are therefore candidates for the next generation of specialized and nanostructured exchange-coupled bulk industrial magnets

Gimme shelter: three-dimensional architecture of the endoplasmic reticulum, the replication site of grapevine Pinot gris virus

Grapevine leaf mottling and deformation is a novel grapevine disease that has been associated with grapevine Pinot gris virus (GPGV). The virus was observed exclusively inside membrane-bound structures in the bundle sheath cells of the infected grapevines. As reported widely in the literature, many positive-sense single-stranded RNA viruses modify host-cell membranes to form a variety of deformed organelles, which shelter viral genome replication from host antiviral compounds. Morphologically, the GPGV-associated membranous structures resemble the deformed endoplasmic reticulum described in other virus-host interactions. In this study we investigated the GPGV-induced membranous structures observed in the bundle sheath cells of infected plants. The upregulation of different ER stress-related genes was evidenced by RT-qPCR assays, further confirming the involvement of the ER in grapevine/GPGV interaction. Specific labelling of the membranous structures with an antibody against luminal-binding protein identified them as ER. Double-stranded RNA molecules, which are considered intermediates of viral replication, were localised exclusively in the ER-derived structures and indicated that GPGV exploited this organelle to replicate itself in a shelter niche. Novel analyses using focussed ion-beam scanning electron microscopy (FIB-SEM) were performed in grapevine leaf tissues to detail the three-dimensional organisation of the ER-derived structures and their remodelling due to virus replication

Antibacterial activity and biodegradation of cellulose fiber blends with incorporated ZnO

This research aimed to study the influence of lyocell with incorporated ZnO (CLY) for antibacterial activity and biodegradation of fiber blends composed of viscose (CV), flax (LI), and CLY. Fiber blended samples with an increased weight fraction of CLY fibers were composed, and single CLY, CV and LI fibers were also used for comparison. Antibacterial activity was determined for the Gram-negative Escherichia coli and the Gram-positive Staphylococcus aureus bacteria. The biodegradation of fiber blends was investigated by the soil burial test. The results show that the single CLY fibers exhibited high antimicrobial activity against both E. coli and S. aureus bacteria and that the presence of LI fibers in the blended samples did not significantly affect antibacterial activity against E. coli, but drastically decreased the antibacterial activity against S. aureus. LI fibers strongly promoted the growth of S. aureus and, consequently, impaired the antimicrobial performance of ZnO against this bacterium. The presence of CLY fibers slowed down, but did not prevent, the biodegradation process of the fiber blends, even at the highest ZnO concentration. The soil that was in contact with the fiber blended samples during their burial was not contaminated to such an extent as to affect the growth of sprouts, confirming the sustainability of the fiber blends

Correlating structural properties with electrochemical behavior of non-graphitizable carbons in Na-ion batteries

We report on a detailed structural versus electrochemical property investigation of the corncob-derived non-graphitizable carbons prepared at different carbonization temperatures using a combination of structural characterization methodology unique to this field. Non-graphitizable carbons are currently the most viable option for the negative electrode in sodium-ion batteries. However, many challenges arise from the strong dependence of the precursor’s choice and carbonization parameters on the evolution of the carbon matrix and its resulting electrochemistry. We followed structure development upon the increase in carbonization temperature with thorough structural characterization and electrochemical testing. With the increase of carbonization temperature from 900 to 1600 °C, our prepared materials exhibited a trend toward increasing structural order, an increase in the specific surface area of micropores, the development of ultramicroporosity, and an increase in conductivity. This was clearly demonstrated by a synergy of small- and wide-angle X-ray scattering, scanning transmission electron microscopy, and electron-energy loss spectroscopy techniques. Three-electrode full cell measurements confirmed incomplete desodiation of Na$^+$ ions from the non-graphitizable carbons in the first cycle due to the formation of a solid−electrolyte interface and Na trapping in the pores, followed by a stable second cycle. The study of cycling stability over 100 cycles in a half-cell configuration confirmed the observed high irreversible capacity in the first cycle, which stabilized to a slow decrease afterward, with the Coulombic efficiency reaching 99% after 30 cycles and then stabilizing between 99.3 and 99.5%. Subsequently, a strong correlation between the determined structural properties and the electrochemical behavior was established

A comparative study of nanolaminate CrN/Mo2N and CrN/W2N as hard and corrosion resistant coatings

Nanolaminate coatings (NLC) consisting of alternated CrN coupled with either cubic tungsten nitride (β-W2N) or molybdenum nitride (γ-Mo2N) were deposited on cold worked tool steel substrates using reactive DC reactive magnetron sputtering for improved mechanical and corrosion resistance. The CrN/γ-Mo2N and CrN/β-W2N nanolaminate systems were found to perform better than the corresponding single-layer systems, with both mechanical and electrochemical properties improving by decreasing the individual layer thickness from 100 to 5 nm. The CrN/β-W2N NLC combined the high hardness value of W2N with the low corrosion current of CrN. The CrN/γ-Mo2N NLC showed synergistic improvements consisting of both higher hardness and lower corrosion currents with respect to the constituent materials alone. The dependence of mechanical and corrosion properties on the bilayer period is discussed in terms of the grain size, residual stresses and texture of the constituent materials and the nanostructured character of the multilayer architecture