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Investigating the electrical and structural properties of Mo and Mo/Ag films deposited by e-beam on silicon nitride is presented. An increasing disorder in the Mo/Ag and reduced proximity coupling between Mo and Ag could be the reason for the unexpected behavior.

Reporting the details of fabrication and characterization of MgB2 films is presented. The results obtained using sapphire as substrate and a two-step method achieving a T(sub c) close to bulk T(sub c) is presented.

LiFePO4/C powders have been synthesised by an easy and inexpensive mild hydrothermal method in the presence of an organic surfactant compound [hexadecyltrimethylammonium bromide (CTAB)] previously developed. The samples have been synthesised with different amounts of CTAB, and the effect of this parameter on their structural characteristics and electrochemical behaviour has been investigated. The processing of the high-resolution diffraction data in a Rietveld refining analysis and the HRTEM observations, previously not available, has put in evidence the high purity of the samples prepared and the good quality of the carbon layer covering the grains. Such layer, obtained during the firing step of the preparation in N2 atmosphere, is very important to enhance the electronic conduction of the electrode. The sample high purity and the conduction enhancer carbon layer, along with the low grain size and high surface area, properties already put in evidence, are obtained to the maximum degree only for a sample prepared with a certain quantity of surfactant. The investigations on samples with very low and with the maximum CTAB content found out the best performing sample confirming the previous results. [ABSTRACT FROM AUTHOR]

Abstract: Exploiting the properties of stability, low cost and low toxicity of iron phosphates, we have tried to enhance the performance of FePO4 as cathode material for Li-ion cells. We adopted the strategy of obtaining FePO4, via a typical preparation, onto the channels of an ordered mesoporous SBA-15 silica, a low cost mesoporous material commonly used in industry, which possesses larger pores, thicker walls and higher thermal stability as compared with other mesoporous silicas like MCM-41. Characterizations with ICP-AES, XRPD, BET and HRTEM suggest that the supported iron phosphate species, with loading amounts as high as 30wt%, are located and dispersed in the mesopores of SBA-15. Iron phosphate can be reduced/oxidized more readily than the unsupported iron phosphate at room temperature, and in fact, cycling at C/10, the supported phosphate shows a utilization of 70% with respect to a value of 30% for the unsupported solid. The result is interesting from the scientific viewpoint but not suitable for application at the moment. Indeed, the amount of active material does not exceed 30% of the electrode mass and the total electrode capacity, though the active material is very efficient, is largely insufficient. Researches are being developed trying to increase the performances of the materials and also to eliminate the support after the dispersion of the active material. [Copyright &y& Elsevier]

Highlights: [•] Mesoporous TiO2 nanocrystalline lithium battery anodes with tunable morphology. [•] Simple sol–gel technique using different cationic surfactants is adopted. [•] Textural/morphological characteristics define the electrochemical behaviour. [•] TiO2 anatase using C16TAB exhibits stable performance after 200 cycles. [•] It shows promising prospects as high-voltage safe Li-ion battery anode. [Copyright &y& Elsevier]

Abstract: Mesoporous TiO2 nanocrystals were prepared by a simple and fast hydrolytic process, in the presence of tetrabutylammonium bromide surfactant, and their ambient temperature electrochemical behaviour as high-rate Li-ion battery anodes was successfully demonstrated even after very long-term cycling (>1000 cycles). Samples were thoroughly characterized by X-ray diffraction, transmission electron microscopy, nitrogen physisorption analyses and electrochemical techniques. Using a novel synthesis approach, regular mesoporous TiO2 anatase phase with a specific surface area of 258m2 g−1 and a good degree of crystallinity was directly obtained without further treatments. The material was also calcined at different temperatures between 250 and 550°C, to increase the degree of crystallization and assess the influence of the structural modifications on the electrochemical characteristics. Very good rate capability and excellent stability upon very prolonged cycling were achieved, thus indicating the prospects of the prepared materials for next-generation high-power lithium-based batteries. [Copyright &y& Elsevier]

Abstract: In this paper, we report the synthesis and characterisation of novel methacrylic based polymer electrolyte membranes for lithium batteries. The method adopted for preparing the solid polymer electrolyte was the UV-curing process, which is well known for being easy, low cost, fast and reliable. It consists of a free radical photo polymerisation of poly-functional monomers: Bisphenol A ethoxylate (15 EO/phenol) dimethacrylate (BEMA) was chosen, as it can readily form flexible 3D networks and has long poly-ethoxy chains which can enhance the movement of Li+-ions inside the polymer matrix. The preliminary results reported here refer to systems where LiPF6 solutions swelled the preformed polymer membranes. The tests on the conductivity, stability and cyclability of the membranes put in evidence the importance of the polymerisation in presence of mono-methacrylates acting as reactive diluents. Good values of ionic conductivity have been found, especially at ambient temperature. Much better results can be expected by choosing an appropriate mono-methacrylate to modify the polymeric membrane properties and by modifying the methodology of Li+-ions incorporation inside the polymer matrix. [Copyright &y& Elsevier]

Abstract: An easy, quick and low cost hydrothermal synthesis was developed to prepare high surface area phospho-olivine LiFePO4 powders to be used as cathode material for Li-ion batteries. The samples were prepared in double distilled water starting from commercial LiOH, FeSO4, H3PO4 and using solutions with different concentrations of a surfactant compound (CTAB), in order to increase the specific surface areas, obtaining powders with very small grain size. The structural, morphological and electrochemical properties were investigated by means of X-ray powder diffraction (XRPD), ICP-AES, BET method, scanning electron microscopy (SEM) and constant current charge–discharge cycling. The electrochemical performances of LiFePO4 prepared in this manner showed to be positively affected by the presence of CTAB during synthesis, showing capacities near the theoretical value, only slightly affected by the discharge regime (from C/20 to 10C). [Copyright &y& Elsevier]

Lithium-oxygen batteries, with their very high energy density (3500 Wh kg -1 ), could represent a real breakthrough in the envisioned strategies towards more efficient energy storage solutions for a less and less carbonated energy mix. However, the problems associated with this technology are numerous. A first one is linked to the high reactivity of the lithium metal anode, while a second one is linked to the highly oxidative environment created by the cell's O 2 saturation. Keeping in mind the necessity for greener materials in future energy storage solutions, in this work an innovative lithium protective membrane is prepared based on chitosan, a polysaccharide obtained from the deacetylation reaction of chitin. Chitosan was methacrylated through a simple, one-step reaction in water and then cross-linked by UV-induced radical polymerization. The obtained membranes were successively activated in liquid electrolyte and used as a lithium protection layer. The cells prepared with protected lithium were able to reach a higher full discharge capacity, and the chitosan's ability to slow down degradation processes was verified by post-mortem analyses. Moreover, in long cycling conditions, the protected lithium cell performed more than 40 cycles at 0.1 mA cm -2 , at a fixed capacity of 0.5 mAh cm -2 , retaining 100% coulombic efficiency, which is more than twice the lifespan of the bare lithium cell.

Lithium-sulfur technology is a strong candidate for the future generation of batteries due to its high specific capacity (1675 mAh g-1), low cost, and environmental impact. In this work, we propose a facile and solvent-free microwave synthesis for a composite material based on doped (sulfur and nitrogen) reduced graphene oxide embedded with zinc sulfide nanoparticles (SN-rGO/ZnS) to improve the battery performance. The chemical-physical characterization (XRD, XPS, FESEM, TGA) confirmed the effectiveness of the microwave approach in synthesizing the composite materials and their ability to be loaded with sulfur. The materials were then thoroughly characterized from an electrochemical point of view (cyclic voltammetry, galvanostatic cycling, Tafel plot, electrochemical impedance spectroscopy, and Li2S deposition test); the SN-rGO/ZnS/S8 cathode showed a strong affinity towards polysulfides, thus reducing their loss by diffusion and improving redox kinetics, allowing for faster LiPSs conversion. In terms of performance, the composite-based cathode increased the specific capacity at high rate (1 C) from 517 to 648 mAh g-1. At the same time, more stable behavior was observed at 0.5 C with capacity retention at the 750th cycle, where it was raised from 32.5% to 48.2%, thus confirming the beneficial effect of the heteroatomic doping process and the presence of zinc sulfide nanoparticles.

Li-O 2 batteries represent a promising rechargeable battery candidate to answer the energy challenges our world is facing, thanks to their ultrahigh theoretical energy density. However, the poor cycling stability of the Li-O 2 system and, overall, important safety issues due to the formation of Li dendrites, combined with the use of organic liquid electrolytes and O 2 cross-over, inhibit their practical applications. As a solution to these various issues, we propose a composite gel polymer electrolyte consisting of a highly cross-linked polymer matrix, containing a dextrin-based nanosponge and activated with a liquid electrolyte. The polymer matrix, easily obtained by thermally activated one pot free radical polymerization in bulk, allows to limit dendrite nucleation and growth thanks to its cross-linked structure. At the same time, the nanosponge limits the O 2 cross-over and avoids the formation of crystalline domains in the polymer matrix, which, combined with the liquid electrolyte, allows a good ionic conductivity at room temperature. Such a composite gel polymer electrolyte, tested in a cell containing Li metal as anode and a simple commercial gas diffusion layer, without any catalyst, as cathode demonstrates a full capacity of 5.05 mAh cm -2 as well as improved reversibility upon cycling, compared to a cell containing liquid electrolyte.

Magnesium-based batteries represent one of the successfully emerging electrochemical energy storage chemistries, mainly due to the high theoretical volumetric capacity of metallic magnesium (i.e., 3833 mAh cm -3 vs. 2046 mAh cm -3 for lithium), its low reduction potential (-2.37 V vs. SHE), abundance in the Earth's crust (10 4 times higher than that of lithium) and dendrite-free behaviour when used as an anode during cycling. However, Mg deposition and dissolution processes in polar organic electrolytes lead to the formation of a passivation film bearing an insulating effect towards Mg 2+ ions. Several strategies to overcome this drawback have been recently proposed, keeping as a main goal that of reducing the formation of such passivation layers and improving the magnesium-related kinetics. This manuscript offers a literature analysis on this topic, starting with a rapid overview on magnesium batteries as a feasible strategy for storing electricity coming from renewables, and then addressing the most relevant outcomes in the field of anodic materials (i.e., metallic magnesium, bismuth-, titanium- and tin-based electrodes, biphasic alloys, nanostructured metal oxides, boron clusters, graphene-based electrodes, etc.).