Electrochemistry in Italy: A Special Section Devoted to the GEI 2013

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review emerging trends in the design of electrolytes for lithium and post lithium batteries

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editorial electrode materials for lithium and post lithium rechargeable batteries

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Synthesis of zirconia/polyethylene glycol hybrid materials by sol-gel processing and connections between structure and release kinetic of indomethacin.

Controlled and local drug delivery systems of anti-inflammatory agents are attracting an increasing attention because of their extended therapeutic effect and reduced side effects. In this work, the sol–gel process was used to synthesize zirconia/polyethylene glycol (ZrO2/PEG) hybrid materials containing indomethacin for controlled drug delivery. Different percentages of PEG were introduced in the synthesis to modulate the release kinetic and an exhaustive chemical characterization of all samples was performed to detect the relationship between their structure and release ability. Fourier transform spectroscopy and solid-state NMR show that the Zr–OH groups of the inorganic matrix bond both the ethereal oxygen atoms of the polymer and the carboxylic groups of the drug. X-ray diffraction analysis ascertains the amorphous nature of those materials. Scanning electron microscopy detects the nanostructure and the homogeneous morphology of the synthesized materials. The bioactivity was demonstrated by the formation of a hydroxyapatite layer on the surface of the samples, after soaking in a simulated body fluid. The release kinetics study, performed by HPLC UV–Vis spectroscopy, proves that the release ability depends on PEG and the drug amount and also demonstrates the indomethacin integrity after the synthetic treatment. Controlled and local drug delivery systems of anti-inflammatory agents are attracting an increasing attention because of their extended therapeutic effect and reduced side effects. In this work, the sol-gel process was used to synthesize zirconia/polyethylene glycol (ZrO2/PEG) hybrid materials containing indomethacin for controlled drug delivery. Different percentages of PEG were introduced in the synthesis to modulate the release kinetic and an exhaustive chemical characterization of all samples was performed to detect the relationship between their structure and release ability. Fourier transform spectroscopy and solid-state NMR show that the Zr-OH groups of the inorganic matrix bond both the ethereal oxygen atoms of the polymer and the carboxylic groups of the drug. X-ray diffraction analysis ascertains the amorphous nature of those materials. Scanning electron microscopy detects the nanostructure and the homogeneous morphology of the synthesized materials. The bioactivity was demonstrated by the formation of a hydroxyapatite layer on the surface of the samples, after soaking in a simulated body fluid. The release kinetics study, performed by HPLC UV-Vis spectroscopy, proves that the release ability depends on PEG and the drug amount and also demonstrates the indomethacin integrity after the synthetic treatment

Cr and Ni doping of Li4Ti5O12: cation distribution and functional properties

Cr- and Ni-doped Li4Ti5O12 compound has been characterized through the combined use of X-ray powder diffraction, electron paramagnetic resonance (EPR), 7Li nuclear magnetic resonance magic-angle spinning (NMR-MAS), micro-Raman, and magnetization measurements. The doping, occurring on the octahedral site of the cubic Li4Ti5O12 spinel lattice, strongly affects both the local and the average structural properties. The glassy character of the observed EPR signals suggests structural disorder in the stable Li4Ti5O12 matrix and the presence of clustering phenomena or nonhomogeneous distribution of the dopant ion, as also supported by 7Li NMR-MAS, micro-Raman, and magnetization results. The computation by numerical method of the complex EPR signal of the Cr-doped sample suggests that both CrTi and CrLi substitutions occur, giving rise to two distinct EPR components, corresponding to opposite axial distortion of the relative octahedral environments. On the basis of the compositional data, defect models involving oxygen or cation vacancies are proposed to explain the conductivity of the doped material

Structure-Property Correlations in Aqueous Binary Na+/K+-CH3COO- Highly Concentrated Electrolytes

Highly concentrated aqueous binary solutions of acetate salts are promising systems for different electrochemical applications, for example, energy storage devices. The very high solubility of CH3COOK allows us to obtain water-in-salt electrolyte concentrations, thus reducing ion activity and extending the cathodic stability of an aqueous electrolyte. At the same time, the presence of Li+ or Na+ makes these solutions compatible with intercalation materials for the development of rechargeable alkaline-ion batteries. Although there is a growing interest in these systems, a fundamental understanding of their physicochemical properties is still lacking. Here, we report and discuss the physicochemical and electrochemical properties of a series of solutions based on 20 mol kg-1 CH3COOK with different concentrations of CH3COONa. The most concentrated solution, 20 mol kg-1 CH3COOK + 7 mol kg-1 CH3COONa, gives the best compromise between transport properties and electrochemical stability, displaying a conductivity of 21.2 mS cm-1 at 25 \ub0C and a stability window of up to 3 V in “ideal” conditions, i.e., using a small surface area and highly electrocatalytic electrode in a flooded cell. Careful Raman spectroscopy analyses help to address the interaction network, the phase evolution with temperature, and the crystallization kinetics

Pair distribution function analysis and Mössbauer study of defects in microwave-hydrothermal LiFePO 4

Olivine-type LiFePO 4 is nowadays one of the most important cathode materials of choice for high-energy lithium ion batteries. Its intrinsic defectivity, and chiefly the so-called lithium iron anti-site, is one of the most critical issues when envisaging electrochemical applications. This paper reports a combined diffractometric (Synchrotron Radiation XRD with Rietveld and PDF analyses) and spectroscopic (Mössbauer) approach able to give a thorough characterization of the material defectivity. Such analytical procedure has been applied to a sample prepared following an innovative microwave-assisted hydrothermal synthesis route that, in a few minutes, allowed us to obtain a well crystallized material. PDF analysis, which is applied for the first time to this type of battery material, reveals the presence of disorder possibly due to Li/Fe exchange or to a local symmetry lowering. A 5% amount of iron on the lithium site has been detected both by PDF as well as by Mössbauer spectroscopy, which revealed a small percentage of Fe 3+ on the regular sites. © 2012 The Royal Society of Chemistry

Cold-setting refractory composites from cordierite and mullite-cordierite design with geopolymer paste as binder: Thermal behavior and phase evolution

Cordierite and mullite-cordierite based geopolymer binders were prepared as refractory bonds to embed coarse kyanite aggregates. Alkali activation was used to consolidate the refractory at room temperature and generate a reactive interface between the matrix and the aggregates. The flexural strength at room temperature of consolidated materials was 11 MPa without kyanite addition, whilst it reached 28 MPa when kyanite was added. The latter showed thermal expansion near to zero up to 500 \ub0C, followed by an expansion of 3c0.5% up to 1000 \ub0C, then a decrease between 1000 and 1050 \ub0C, concluding with a constant value of expansion <0.5% up to 1250 \ub0C. The increase in expansion was found to be linked to the transformation of the geopolymer into ceramic bond with the formation of crystalline phases, while the decrease was apparently related to the liquid phase sintering. The stability of mullite, cordierite and leucite formed up to 1250 \ub0C was responsible for the constant expansion observed up to this temperature. The mechanical properties, the phase evolution and the thermal behavior of the K2O-MgO-Al2O3-SiO2 bonds, together with the refractory behavior of kyanite aggregates, were found suitable for the design of sustainable cold-setting refractory composites

Polymer-in-Ceramic Nanocomposite Solid Electrolyte for Lithium Metal Batteries Encompassing PEO-Grafted TiO2 Nanocrystals

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