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The increase in energy density of the next generation of battery materials to meet the new challenges of the electrical vehicles era calls for innovative and easily scalable materials with sustainable processes. An innovative CuxO/C nanocomposite material, characterized by a highly conductive 3D‐framework, with CuxO/Cu‐metal contiguous nanodomains is prepared by electrospinning. The electrode processing is made using a polyacrylic acid binder. The nanocomposite has been fully characterized and the electrochemical performance shows high specific capacity values over 450 galvanostatic cycles at 500 mAg−1 specific current with capacity retention values over 80 %. In addition, the composite shows remarkable high rate performance and highly stable interface, which has been studied by impedance spectroscopy. [ABSTRACT FROM AUTHOR]

Al K-edge XANES spectra were recorded for six tektites to obtain information on the local structure around Al. Albite, grossular, and andalusite were used as reference materials for Al in fourfold, sixfold, and five+sixfold coordination, respectively. The spectra of the tektites are very similar, except for the intensity of the main absorption edge. Comparison of the spectral features of the tektite glasses with those of the reference materials indicates that Al is tetrahedrally coordinated.

The structure of glasses in the [K.sub.2]O-[Al.sub.2][O.sub.3]-Ti[O.sub.2]-Si[O.sub.2] system was investigated using XANES spectroscopy. Glass samples, synthesized by quenching in air from high temperature fusions, represent the addition of [Al.sub.2][O.sup.3] to a base of composition [K.sub.2]Ti[Si.sub.4][O.sub.11] in amounts corresponding to 0.25, 0.50, 0.75, 1.00, 1.25, and 1.50 mol p.f.u. In the Ti-free system, this range of alkali/aluminum ratios crosses the leucite stoichiometry at 1.0. Si K-edge and Al K-edge spectra indicate tetrahedral environments for these elements, and show no variations related to coordination change as a function of Al content. Changes in the relative intensities of peaks in the Al K-edge, however, suggest variation in the intertetrahedral (T-O-T) angle. We associate the decrease of this angle for the glasses of peraluminous composition with the presence of triclusters of tetrahedra. The pre-edge peak absorption features in the Ti K-edge XANES spectra indicate that the average Ti coordination decreases with the addition of [Al.sub.2][O.sub.3]. We infer depletion of fivefold-coordinated titanium (possibly as alkali titanyl complexes), which are dominant in the Al-flee glass, by the formation of fourfold coordinated Ti and alkali aluminate complexes (up to a concentration of 40% in the most peraluminous glass). Significant amounts of [sup.[V]]Ti remain present, even at peraluminous compositions, in further support of tricluster formation as a mechanism for Al incorporation.

A systematic study is presented on a set of vanadium-bearing model compounds, representative of the most common V coordination geometries and oxidation states, analysed by means of vanadium K-edge X-ray absorption near-edge spectroscopy calculations in the full multiple scattering (FMS) framework. Analysis and calibration of the free parameters of the theory under the muffin-tin approximation (muffin-tin overlap and interstitial potential) have been carried out by fitting the experimental spectra using the MXAN program. The analysis shows a correlation of the fit parameters with the V coordination geometry and oxidation state. By making use of this correlation it is possible to approach the study of unknown V-bearing compounds with useful preliminary information. [ABSTRACT FROM AUTHOR]

Nanostructured Li3V2−xNix(PO4)3 (x = 0, 0.05, and 0.1) cathode materials, with a mean particle dimension ranging from 200 to 63 nm, are successfully synthesized with poly(acrylic acid) and d-(+)-glucose as carbon sources. All three samples show a monoclinic crystalline structure as confirmed by X-ray diffraction and Rietveld analysis. Ni-doping improves the specific capacity of Li3V2(PO4)3/C. Between 3.0 and 4.3 V vs. Li+/Li, all cathodes exhibit good rate capability, even at high C-rates. For these reasons, they are good candidates for high power and energy applications, in particular for the development of high energy density supercapacitors. Li3V1.95Ni0.05(PO4)3/C, because of its highest specific discharge capacity (93 mA h g−1 at 100 C) and capacity retention of 97% after 1000 cycles, is selected for building an asymmetric supercapacitor with activated carbon as the anode. At a power density of 2.8 kW L−1, the asymmetric system delivers 18.7 W h L−1, a value five orders of magnitude higher than that of the symmetric capacitor at the same power level. [ABSTRACT FROM AUTHOR]

The understanding of redox equilibria as well as the knowledge of the elemental distribution in magmatic melts are of fundamental importance to constrain the genesis of magmas. In particular, the partitioning of trace elements (e.g., Eu) has demonstrated to be a useful tool for estimating the redox conditions in Earth and planetary materials. However, for a more complete comprehension of Eu in silicate melts, information regarding the effects of temperature (T), redox conditions, compositions, and the possible interference of other multivalent elements is still lacking. Here we provide new data on the oxidation states of two commonly coexistent multivalent elements (Eu and Fe) in melts, acquired by "in situ" dispersive X-ray absorption spectroscopy experiments at high temperatures and at different oxygen fugacity conditions. This work, for the first time, shows the possibility to monitor in real-time the behavior and valence variations of two elements under varying environmental conditions (like T and redox state). [ABSTRACT FROM AUTHOR]