Search

Natrium super ionic conductor (NASICON) materials providing attractive properties such as high ionic conductivity and good structural stability are considered as very promising materials for use as electrodes for lithium- and sodium-ion batteries. Herein, a new high-performance electrode material, Li0.5Ni0.5Ti1.5Fe0.5(PO4)3/C, was synthesized via the sol-gel method and was electrochemically tested as an anode for lithium ion batteries, providing enhanced electrochemical performance as a result of nickel substitution into the lithium site in the LiTi2(PO4)3 family of materials. The synthesized material showed good ionic conductivity, excellent structural stability, stable long-term cycling performance, and improved high rate cycling performance compared to LiTi2(PO4)3. The Li0.5Ni0.5Ti1.5Fe0.5(PO4)3/C electrode delivered reversible capacities of about 93 and 68% of its theoretical one at current rates of 0.1 C (6.42 mA·g-1) after 100 cycles and 5 C (320.93 mA·g-1) after 1000 cycles, respectively. Theoretically, three Li+ ions can be inserted into the vacancies of the Li0.5Ni0.5Ti1.5Fe0.5(PO4)3/C structure. However, when the electrode is discharged to 0.5 V, more than three Li+ ions are inserted into the NASICON structure, leading to its structural transformation, and thus to an irreversible electrochemical behavior after the first discharge process.

A novel radiation grafted ETFE based proton conducting membrane was prepared by double irradiation grafting of two different monomers. The intrinsic oxidative stability of the ETFE-g-poly(styrene sulfonic acid-co-divinylbenzene) membrane was improved by reducing the gas crossover through incorporation of polymethacrylonitrile (PMAN) containing the strong polar nitrile group. A fuel cell test was carried out at 80 °C under constant current density of 500 mA cm−2 for a time exceeding 1′900 h. The incorporation of PMAN considerably improves the interfacial properties of the membrane-electrode assembly. No significant change in the membrane hydrogen crossover and performance over the testing time was observed, except for a measured decrease in the membrane ohmic resistance after 1′000 h. The combination of the double irradiation induced grafting with the use of the PMAN as gas barrier in addition to its chelating abilities (e. g. Ce3+) offers a promising strategy to develop more durable membranes for fuel cells.

Alfa fibers (Stipa Tenacissima) were effectively utilized in this study as a promising cellulose source for isolation of carboxy-functionalized cellulose nanofibrils (CNFs) using multiple treatments. Pure cellulose microfibers (CMFs) were firstly extracted by alkali and bleaching treatments. CNFs with an average nanofibrils diameter ranging from 1.4 to 4.6 nm and a crystallinity of 89% were isolated from CMFs by a combination of TEMPO-oxidation and mechanical disintegration processes. The morphology and physico-chemical properties of cellulosic materials were evaluated at different stages of treatments using several characterization techniques. Various CNF loadings (5–15 wt%) were incorporated into PVA polymer to evaluate the nanoreinforcement ability of CNFs and to produce CNF-filled PVA nanocomposite materials. The tensile and optical transmittance properties, as well as the morphological and thermal properties of the as-produced CNF-filled PVA nanocomposite films were investigated. It was found that the tensile modulus and strength of nanocomposites were gradually increased with increasing of CNF loadings, with a maximum increase of 90% and 74% was observed for a PVA nanocomposite containing 15 wt% CNFs, respectively. The optical transmittance was reduced from 91% (at 650 nm) for neat PVA polymer to 88%, 82% and 76% for PVA nanocomposites containing 5, 10 and 15 wt% CNFs, respectively. It was also found that the glass transition temperature was gradually increased from 76 °C for neat PVA to 89 °C for PVA nanocomposite containing 15 wt%. This study demonstrates the importance of Alfa fibers as annual renewable lignocellulosic material to produce CNFs with good morphology and excellent properties. These newly developed carboxy-functionalized CNFs could be considered as a potential nanofiller candidate for the preparation of nanocomposite materials of high transparency and good mechanical properties.

The present work describes the production of novel highly hydrated cellulose microfibrils (CMFs) with unique morphology from coffee pulp waste using specific chemical treatments. The as-produced CMFs were successfully characterized and then used as an adsorbent for removal of methylene blue (MB) from concentrated aqueous solutions. Surprisingly, it was found that the novel CMFs display high water-uptake ability, with a maximum swelling ratio of 265%, and that they form an entangled hydrated network gel in water. The morphological observation and nitrogen adsorption measurement demonstrated that the extracted CMFs exhibit an average fibril diameter of 11.5 µm and mesoporous structure with an average pore size of 6.37 nm. These special features make the as-produced CMFs excellent candidates to be used as adsorbents for removal of MB from concentrated solutions. The performed adsorption studies determined that the adsorption equilibrium was reached within 90 min. The adsorption kinetics data were well fitted to the pseudo-second-order kinetic model, and the adsorption isotherms were well described by the Freundlich isotherm model. In addition, the maximum adsorption capacity was 182.5 mg/g, much higher than that determined for other previously reported cellulose-based adsorbents. Through this study, we have demonstrated a possible strategy to give an added value to the coffee pulp waste, a by-product of the coffee processing industry, which is rich in cellulose, inexpensive and renewable source. Indeed, the extracted CMFs are very attractive for developing a sustainable and economically viable bio-sourced material for future growth of cellulose use in advanced applications.

This work reports on the preparation of oil-filled microcapsules for self-healing purposes. Biopolymeric microcapsules loaded with vegetable oils as green corrosion inhibitors were formulated using ethyl cellulose and phosphorylated ethyl cellulose as encapsulating materials. Chemical structure, thermal stability and surface morphology of microcapsules were characterized by Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). FTIR and TGA analysis confirmed the presence of oil core and polymer shell in the formulated microcapsules. The scanning electron microscopy was used to evaluate the shape and morphology of the prepared microcapsules. The obtained results revealed the spherical-like shape of the obtained capsules with diameters ranging from 10 up to 170 µm. Thus, the current study shows the potential application of phosphorylated ethyl cellulose for the development of new environmentally friendly microcontainers bearing corrosion inhibitors for end use in anti-corrosion self-healing coatings.

This study reports for the first time the preparation of almond oil-based microcapsules using phosphorylated ethyl cellulose as shell material. Microcapsules of ethyl cellulose (EC) and phosphorylated ethyl cellulose (P-EC) containing almond oil as anti-corrosion inhibitor, for end use in self-healing coatings, were prepared by a solvent evaporation method. The results showed that phosphorus content in the modified ethyl cellulose was 6.26 wt.%, the specific surface area reached a high value of 21.4 m2 g−1 and a char residue of 18 wt.% at 400 °C after thermal degradation. Both prepared EC and P-EC based microcapsules were spherical shape-like. The scanning electron microscope (SEM) images showed that the freeze-drying influences the microcapsules surface morphology. The mean diameter of EC and P-EC microcapsules was about 140 μm and 150 μm, respectively. Anti-corrosion properties of prepared epoxy-based coatings loaded with microcapsules on the mild steel substrate were evaluated for 28 days using a simple salt spray test. The sample containing P-EC microcapsules showed the best anticorrosion resistance. The functionalization of the ethyl cellulose microcapsules shell with phosphonate groups can improve further the anti-corrosion resistance, the flame-retardant ability and the metal chelating properties of the final coatings.

In the present work, cellulose nanocrystals (CNC) were produced from vine shoots waste using chemical treatments followed by acid hydrolysis process. FTIR analysis confirmed that the non-cellulosic components were progressively removed during the chemical treatments, and the final obtained materials are composed of pure cellulose. AFM and TEM observations showed that the extracted CNC possess a needle-like shape with an average length of 456 nm and an average diameter of 14 nm, giving rise to an average aspect ratio of about 32. The as-extracted CNC exhibit a cellulose I structure with high crystallinity index (82%), as determined by XRD characterization. Importantly, the resulted CNC provide a higher thermal stability in comparison with CNC extracted from other resources, using the same extraction process. The isolated CNC's surface charge density was evaluated by XPS analysis and resulted in ~2.0 sulfate groups per 100 anhydroglucose units. In order to identify the reinforcing ability of the new extracted CNC, Carboxymethyl cellulose nanocomposite films were prepared with various CNC contents (1, 3, 5, 8 wt%) and their mechanical properties were investigated by uniaxial tensile test. The results showed that the as-extracted CNC displayed a higher reinforcing ability for nanocomposite materials.

Cellulose nanocrystals (CNC) were extracted from Miscanthus (MST) fibers using a sulfuric acid hydrolysis process. The results showed that the obtained CNC exhibit a needle-like shape with an average aspect ratio of 37. The surface charge density was measured at 1.99 sulfate groups per 100 anhydroglucose units while the zeta potential value was found to be -38 mV. The crystallinity of the extracted CNC was 76%, and the cellulose I type crystal structure was predominant. Due to its high importance for potential application of CNC in aqueous systems, the rheological behavior of CNC aqueous suspensions at various CNC concentrations was determined. The CNC suspensions showed gel-like behavior at very low CNC concentrations ranging from 0.1 wt% up to 0.6 wt%, as confirmed by the steady shear viscosity measurements and the oscillatory dynamic tests. The dynamic rheological parameters of CNC suspensions were slightly affected by the temperature profile. At high temperature up to 80 °C a stronger CNC network is formed by increasing the relative motion resistance of CNC macromolecules and the entanglement. In order to identify the reinforcing ability of the newly extracted CNC, starch-based nanocomposite films were produced with various CNC contents (1, 3, 5 and 8 wt%) and their tensile properties were investigated. It was found that the addition 8 wt% CNC within starch matrix increased the Young’s modulus by 150% and the tensile strength by 118%, resulting in mechanically strong and eco-friendly nanocomposite materials.

Inverse vulcanization copolymers (p(S-DVB)) from the radical polymerization of elemental sulfur and divinylbenzene (DVB) have been studied as cathode active materials in poly(ethylene oxide) (PEO)-based all-solid-state Li-S cells. The Li-S cell comprising the optimized p(S-DVB) cathode (80:20 w/w S/DVB ratio) and lithium bis(fluorosulfonyl)imide/PEO (LiFSI/PEO) electrolyte shows high specific capacity (ca. 800 mAh g −1 ) and high Coulombic efficiency for 50 cycles. Most importantly, polysulfide (PS) shuttle is highly mitigated due to the strong interactions of PS species with polymer backbone in p(S-DVB). This is demonstrated by the stable cycling of the p(S-DVB)-based cell using lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)/PEO electrolyte, where successful charging cannot be achieved even at the first cycle with plain elemental S-based cathode material due to the severe PS shuttle phenomenon. These results suggest that inverse vulcanization copolymers are promising alternatives to elemental sulfur for enhancing the electrochemical performance of PEO-based all-solid-state Li-S cells.

New synthesis route of polysalt with single ion conductivity based on functionalization of polyacrylic acid is reported for all solid state lithium metal batteries. Poly[(trifluoromethyl)sulfonyl acrylamide] PA–LiTFSI was synthesized in two steps reaction. The degree of functionalization of the polymer backbone by anion of lithium salt bis(trifluoromethane)sulfonimide (LiTFSI) was confirmed by ICP analysis. An ionic conductivity equal 1,77 10 −5 S cm −1 at 80 °C of polysalt blended with PEO is reported. Easy process-able polysalt blended with PEO exhibits good mechanical properties and high transference number.

Semi-interpenetrated network Solid Polymer Electrolytes (SPEs) were fabricated by UV-induced cross-linking of poly(ethyleneglycol) diacrylate (PEGDA) and divinylbenzene (DVB) within a poly(ethyleneoxide) (PEO) matrix (Mv = 5 × 106 g mol−1), comprising lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI), at a molar ratio of EO:Li ∼ 30:1. The influence of the DVB content on the final SPE properties was investigated in detail. An increase of DVB concentration resulted in self-standing polymer electrolytes. The DVB cross-linker incorporation was found to decrease the crystallinity of the PEO matrix from 34% to 23%, with a decrease in the melting temperature (Tm) of the membrane from 50 °C to 34 °C. Moreover, the influence of the DVB concentration on the ionic conductivity was determined for polymer electrolytes with 0, 10, 20 and 45% DVB from room temperature (RT) to 80 °C. The resulting SPEs showed a high electrochemical stability of 4.3 V as well as practical conductivity values exceeding 10−4 S cm−1 at 70 °C. Cycling performance of these semi-interpenetrated SPE’s have been shown with a Li metal polymer battery and all solid -state Li sulphur battery.

Lithium-Sulfur (Li-S) battery technology is one of the promising candidates for next generation energy storage systems. Many studies have focused on the cathode materials to improve the cell performance. In this work we present a series of poly (S-DVB) copolymers synthesised by inverse vulcanization of sulfur with divinylbenzene (DVB). The poly (S-DVB) cathode shows excellent cycling performances at C/2 and C/4 current rates, respectively. It was demonstrated poly (S-DVB) copolymer containing 20% DVB did not influence the electrochemical performance of the sulfur material, compared to elemental sulfur as high specific capacities over ∼700 mAh g −1 at 500 cycles were achieved at C/4 current rate, comparable to conventional carbon-based S cathodes. However, the use of copolymer network is assumed to act firstly as sulfur reservoir and secondly as mechanical stabilizer, enhancing significantly the cycling lifetime. The Li-poly (S-DVB) cell demonstrated an extremely low degradation rate of 0.04% per cycle achieving over 1600 cycles at C/2 current rate.

Phosphate materials became attractive electrode materials for sodium ion batteries due to their high capacity and safety properties. Cobalt iron (III) oxyphosphate CoFeOPO4@C was successfully prepared by conventional solid-state reaction at an annealing temperature of 1000 °C in air atmosphere. Our group previously reported the electrochemical properties of this material versus Li+/ Li. In this paper, we study for the first time the electrochemical activity of CoFeOPO4@C in sodium half-cells and evaluate its potential use as an anode material for sodium ion batteries. CoFeOPO4@C shows a high discharge capacity of 479 mAh g−1 at C/2 current rate over 0.01–3.0 V voltage range during the first cycle by accommodating around four sodium ions. Although the first irreversible capacity is relatively high resulting from a conversion mechanism, this phosphate can reversibly exchange about two sodium ions in the subsequent cycles, delivering a capacity of more than 200 mAh g−1 with a coulombic efficiency exceeding 97%.

Partial lithium substitution with nickel (0.25 of Ni2+ ion) in the previously reported Li1.5Fe0.5Ti1.5(PO4)3/C (LFTP@C) was performed to improve its structural and electrochemical properties. The new LiNi0.25Fe0.5Ti1.5(PO4)3/C (LNFTP@C) material was then tested as electrode for lithium ion batteries. In the voltage window 1.85V–3.0 V vs. Li+/Li, attractive electrochemical performances were obtained, mostly in terms of rate capability performance. At a current rate of 0.1C (6.6 mAg−1), the material delivered a capacity of around 120 mAhg−1, while at 5C, we observed a slight drop of the specific capacity reaching a value of 108 mAhg−1. Long-term cycling performance stability was also tested demonstrating a remarkable capacity decrease during the last 500 cycles. The capacity retention decreased from 94% to 91% after 500 cycles to about 77% and 74% after 1000 cycles at fast current rates of 5C (329.8 mAg−1) and 10C (659.6 mAg−1), respectively. In the wider voltage window, an average specific capacity of around 380 mAhg−1 was attained at a slow current rate of 0.1C.

Solid polymer electrolytes (SPEs) with new functionalized ethyl cellulose bearing a lithium/sodium fluorosulfonylimide group (Ethyl cellulose-LiFSI/NaFSI) is proposed as quasi single ion (Li+/Na+) conducting polymer electrolyte for all-solid-state lithium and sodium batteries. The degree of ethyl cellulose functionalization by anion of lithium and sodium salt measured by elemental analysis was 48 and 53%, respectively. The complex of Li(FSI-ethyl cellulose)/PEO exhibits a Li-ion transference number of TLi+ = 0.9, and a Na ion transference number of TNa+ = 0.6 for Na(FSI-ethyl cellulose),which are much higher than those reported for ambipolar LiFSI or NaFSI/PEO SPEs under the same measurement conditions. The generated SPEs showed a high electrochemical and mechanical stability as well as a practical ionic conductivity value of ~10−4 S·cm−1 at 80 °C. All solid-state lithium, sodium and Li/Sulfur cells cycled with quasi single ion conducting hybrid SPE exhibit reversible cycling and good performance at 70 °C, making them promising, environmentally benign and cost-effective candidates for use in advanced energy storage systems.

Design of novel phosphorus apatites, K2Pb6Zn2(PO4)6 and K2Pb4Ca4(PO4)6, zinc hydroxyapatite Ca8Zn2(PO4)6(OH)2, as well as hydroxyapatite Ca10(PO4)6(OH)2, and its corresponding calcined powder were conducted by means of two different synthesis protocols, i.e. solid state and wet chemical methods. The prepared materials adopt P63/m (No 176) as a space group. Structural refinements for K2Pb6Zn2(PO4)6 and K2Pb4Ca4(PO4)6 lacunar apatites, and that for the calcined hydroxyapatite, were performed using Rietveld method. For K2Pb6Zn2(PO4)6, the refinement results showed that the majority of Pb2+ cations occupy (6h) sites. This study examines the impact of the synthesis conditions on the physico-chemical properties and on the surface reactivity of the prepared materials. The analysis of the interactions of the samples with respect to a protein model (Bovin Serum Albumin), evaluated under the same experimental conditions, revealed a fast-kinetic process for the precipitated samples, compared to the crystals obtained by solid chemical reaction. Thus, the equilibrium conditions were reached in less than 20 min for the former while 6 h of contact were requested for the latter. However, all the obtained isotherms show a Langmuirian shape. The difference in the adsorption parameters of the materials, i.e. constant affinity and amount adsorbed at saturation, is discussed in terms of surface characteristics, chemical composition, crystals size and specific surface area. It is concluded that the interaction with the Bovin Serum Albumin (BSA) molecules is highly sensitive to the microstructure of the crystals.

Green energy harvesting (solar and wind) and storage along with electrification of transport sector could bring about a major transformation in the CO2 emission levels that we are currently experiencing. Lithium ion batteries provide an efficient energy storage system to realize this goal. The key developments in Li-ion battery technology starting from solid solution electrodes, intercalation electrodes, conversion electrodes, organic electrodes, and polymer electrolytes with a major focus on the contribution of Michel Armand, an eminent scientist who at a young age saw the future of energy storage, have been elaborated. Moreover, the direction of research that seems interesting to pursue for realizing our goals has also been outlined.

Two new cathode materials based on redox organosulfur polymers were synthesized and investigated for rechargeable lithium batteries as a proof-of-concept study. These cathodes offered good cycling performance owing to the absence of polysulfide solubility, which plagues Li/S systems. Herein, an aliphatic polyamine or a conjugated polyazomethine was used as the base to tether the redox-active species. The activity comes from the cleavage and formation of S−S or N−S bonds, which is made possible by the rigid conjugated backbone. The synthesized polymers were characterized through FTIR spectroscopy and thermogravimetric analysis (TGA). Galvanostatic measurements were performed to evaluate the discharge/charge cycles and characterize the performance of the lithium-based cells, which displayed initial discharge capacities of approximately 300 mA h g−1 at C/5 over 100 cycles with approximately 98 % Coulombic efficiency.

We report on correlations between the proton conductivity, the water swelling and the dry-state morphology of ETFE-g-poly(sulfonated styrene-co-DVB) proton-exchange membranes (PEMs). We focus on the influence of the systematically varied monomer composition. Especially, the impact of the DVB cross-linker on the ion-rich phase aggregated in the dry PEM is studied by small-angle X-ray scattering. A modified hard-sphere fluid model describing the ion-rich phase is applied to interpret the observed scattering function. We find hereby that the size and number density of the ion-rich domains decrease with increasing cross-link level. Consequently, the distance between the ion-rich domains is proportional to the cross-link level. The total volume fraction of water in the hydrated membrane is proportional to the overall volume fraction of the ion-rich phase, and the number of water molecules per ion-rich aggregate is inversely proportional to the level of cross-linking. We show that there is a clear correlation between the structure of the ion-rich phase formed in the dry state and the proton conductivity of the hydrated membrane: beyond a threshold, indicating the onset of percolation of the aqueous network, the conductivity is proportional to the hydration level and inversely proportional to the mean distance between the ion-rich domains.