The Missing Piece: The Structure of the Ti3C2TxMXene and Its Behavior as Negative Electrode in Sodium Ion Batteries

The most common MXene composition Ti3C2Tx (T = F, O) shows outstanding stability as anode for sodium ion batteries (100% of capacity retention after 530 cycles with charge efficiency >99.7%). However, the reversibility of the intercalation/deintercalation process is strongly affected by the synthesis parameters determining, in turn, significant differences in the material structure. This study proposes a new approach to identify the crystal features influencing the performances, using a structural model built with a multitechnique approach that allows exploring the short-range order of the lamella. The model is then used to determine the long-range order by inserting defective elements into the structure. With this strategy it is possible to fit the MXene diffraction patterns, obtain the structural parameters including the stoichiometric composition of the terminations (neutron data), and quantify the structural disorder which can be used to discriminate the phases with the best electrochemical properties

The Doping of FeNb11O29 as a Way to Improve Its Electrochemical Performances

FeNb11O29, with the possibility to exchange up to 23 electrons per formula unit and a theoretical capacity value of 400 mAh/g, is nowadays a very promising anode material for Li-ion batteries. However, the improvement of its electrochemical performances is still an open challenge, and the doping is a well-recognized method to obtain this goal. In this paper, orthorhombic Fe0.8Mn0.2Nb11O29 and Fe0.8V0.2Nb11O29 samples were prepared by solid state synthesis. The redox processes, as determined by cyclic voltammetry, involve only Fe and Nb ions as in the undoped compound. FeNb11O29 is a well-known mixed oxide with pseudocapacitive behavior, which is increased with the Mn doping. The doped samples show better performances during long term cycling at 2 C, with capacities of 240 and 220 mAh/g and capacity retention of 100.9 and 98.7% for Mn and V doped respectively

Na+diffusion mechanism and transition metal substitution in tunnel-type manganese-based oxides for Na-ion rechargeable batteries

Na0.44MnO2 (NMO) with a tunnel-type structure is a reference cathode material for rechargeable Na-ion batteries. In this work, structural, electrochemical and computational investigations are combined to study the properties of this material, particularly with reference to Cu substitution in the structure. For the first time, molecular dynamics (MD) is used to obtain insights into the mechanisms of Na+ diffusion in NMO, highlighting the role of structural modifications and Na distribution. The main results allow the investigation of the implication of high temperature treatments and the effect of Cu substitution on the defect and transport properties of the material with a tunnel-type structure. From an experimental point of view, the substitution promotes an increased stability of the material upon cycling and an improved capacity particularly at higher discharging rates, that stems from the synergistic effects of the composition, morphology and multiple polymorphs of the sample

The peculiar dissolution behaviour of Piretanide hosted in layered double hydroxides

Layered double hydroxides (LDHs) are widely used as inorganic hosts for different applications, in particular for drug delivery. Piretanide, a poorly soluble diuretic drug, could benefit of the association with LDH for improving the dissolution rate and also for limiting the gastric irritation after its repeated administration thanks to natural antacid properties of LDH. In this paper, the hybrids compounds Piretanide-Mg3Al-LDH and Zn3Al-LDH were synthesized by co-precipitation method. The first proofs to demonstrate the successful intercalation came from X-ray powder diffraction (from hydroxide layers expansion with respect to LDH-carbonate), thermal analysis (from the absence of drug melting point in the hybrid compound) and infrared spectroscopy (from the absence of the carboxylic acid vibration in the hybrid). In addition, SEM microscopy/EDS microanalysis supported the formation of new entities. Both compounds showed a significant improvement of the drug dissolution rate, compared to the active alone, in biorelevant conditions simulating the oral administration

High-rate V2O5-based Li-ion thin film polymer cell with outstanding long-term cyclability

An innovative V2O5 based multiphase electrode/electrolyte composite is prepared by a fast, versatile and easily scalable UV-induced free-radical photo-polymerisation technique and its electrochemical properties are thoroughly investigated. The compact configuration consists of a highly conducting methacrylic-based polymer electrolyte directly formed over a r.f. sputtered V2O5 thin film positive electrode. All-solid state thin-film Li and Li-ion cells are assembled by simply contacting the polymeric side of the compact composite with either lithium or graphite as anode in the respective cases, and long-term galvanostatic charge/discharge cycling studies are performed. The FESEM analysis after long-term cycling confirms the active role of the polymer electrolyte in stabilizing the cycling behaviour which, in turn, prolonged the life span of the cell operation. Such an assembly is one of the finest example in which a solid Li-ion polymer cell is cycled at a rate as high as 5C at ambient temperature. The results of the electrochemical and morphological studies confirm that the methodology presented here is versatile and economical to produce a well-functioning and easily up scalable Li-ion thin film battery

Meloxicam-LDH Hybrid Compound: A Successful Strategy to Improve Solubility

The use of nanohybrids containing cationic or anionic inorganic compounds, seems particularly promising as efficient strategy for drug delivery. In fact, the inorganic counterions usually present in the host can be easily exchanged with drug molecules, from antitumor to anti-inflammatory, antibiotics and vitamins, giving rise to composites with improved solubility. An interesting inorganic host emerging for different applications, from catalysis to water purification up to pharmaceutics, is the layered double hydroxide (LDH) possessing a sheets structure and formula [M1-x2+Mx3+ (OH)2](An−)x/n yH2O (M2+= Zn, Mg; M3+= Al; An− = nitrates, carbonates, chlorides). In this paper, we synthesize by co-precipitation and reconstruction methods the hybrid compound Meloxicam-Zn3Al-LDH, particularly useful for a poorly soluble anti-inflammatory drug. The effective drug intercalation into LDH was verified through X-ray powder diffraction, thermal measurement and infrared spectroscopy. In addition, microscopy/microanalysis supported the formation of new entities. The dissolution tests clearly demonstrate an amazing improvement of the drug release rate with respect to marketed compounds when meloxicam is in the form of hybrid compound

Fabrication and electrochemical characterization of amorphous lithium iron silicate thin films as positive electrodes for lithium batteries

In this work we reported, for the first time, the preparation by radio frequency sputtering and the electrochemical characterization of Li/M/Si/O thin films (M ¼ Fe, Mn), as positive electrodes for lithium microbatteries. The deposited films were amorphous both in case of pure iron and mixed iron/manganese compositions. The electrochemical performances, in terms of capacity values and coulombic efficiency, were comparable to those currently reported for the corresponding crystalline bulk materials. In particular, capacities of the order of 50 mAh g1 were obtained at 2.5 C with coulombic efficiency near 90% by using a standard liquid electrolyte. Our preliminary electrochemical results, together with the easiness of preparation, suggested that Li/M/Si/O thin films could be interesting candidates as cathodes in lithium microbatteries