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Despite the interest in proton exchange membrane (PEM) technologies (fuel cells and electrolyzers) for energy applications, the low stability of the electrolyte materials under working conditions (i.e., humidity and temperature) is one of their major limitations. Metal–organic frameworks (MOFs) have recently emerged as promising electrolytes due to their higher stability compared with the currently applied organic polymers, proton conductivity, and outstanding porosity. Here, a novel robust Bi phosphonate MOF (branded as IEF-7) was successfully synthesized and fully characterized, exhibiting an unusual topology due to the irregular coordination geometry of the bismuth cations. Furthermore, IEF-7 exhibited potential porosity, very high chemical and thermal stability, and free −PO3H groups involved in its ultrahigh proton conductivity, reaching 1.39 × 10–2S cm–1at 90 °C and 90% relative humidity for, at least, 3 cycles. In order to improve the consolidation and shaping of the powder for testing its ion conductivity properties, a highly MOF-loaded composite (90 wt %) was prepared by adding a proton conductive sulfonated polysulfone binder. The proton conductivity of the resulting composite was in the same order of magnitude as the compacted MOF powder, making this polymeric composite electrolyte very promising for PEM technologies.

Proton-exchange membrane fuel cells are an attractive green technology for energy production. However, one of their major drawbacks is instability of the electrolytes under working conditions (i.e., temperature and humidity). Some metal–organic frameworks (MOFs) have recently emerged as promising alternative electrolyte materials because of their higher stability (compared with the organic polymers currently used as electrolytes), proton conductivity, and outstanding porosity and versatility. Here, we present ionic exchange in a microporous zirconium phosphonate, UPG-1, as an efficient strategy to enhance its conductivity and cyclability. Thus, labile protons of the hybrid structure were successfully replaced by different alkali cations (Li+, Na+, and K+), leading to 2 orders of magnitude higher proton conductivity than the pristine UPG-1 (up to 2.3 × 10–2S·cm–1, which is comparable with those of the commercial electrolytes). Further, the proton conductivity was strongly influenced by the MOF hydrophilicity and the polarization strength of the cation, as suggested by molecular simulation. Finally, a mixed-matrix membrane containing the best-performing material (the potassium-exchanged one) was successfully prepared, showing moderate proton conductivity (up to 8.51 × 10–3S·cm–1).

In order to extend the application of graphene oxide (GO) in the area of electronic industries, enhancing the electrical properties of GO as a cost-effective alternative for graphene seems mandatory. Engineering the electrical properties of GO can be achieved in two different approaches: the oxygen functional group reduction and doping GO with chemical dopants. Here, both approaches were utilized to tune the electrical properties of GO toward its application as cathode; first, GO was doped with alkali metal dopants, and later, the doped samples were thermally reduced. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy were utilized to study the chemical composition of the doped samples. The even distribution of the dopants on the GO surface presented via the EDX elemental map, with no sign of particle development. After doping GO with alkali metals followed by thermal reduction, the sheet resistance of the doped samples was decreased from 311.0 kΩ/sq to as low as 32.1 kΩ/sq. Moreover, the optical properties of GO were effectively engineered via the different doping agents. The ultra-violet photoelectron spectroscopy showed that the shift of the work function of GO was as high as 1.74 eV, after doping followed by thermal reduction.

This study presents a comprehensive life cycle assessment (LCA) of liquid lithium-ion batteries (liquid LIB), liquid sodium-ion batteries (liquid SIB), and solid sodium-ion batteries (solid SIB) to evaluate their environmental impacts in a laboratory scale. The results emphasize the potential environmental benefits of adopting solid SIBs as they show considerable savings in toxicity categories compared to conventional lithium-ion batteries. Moreover, solid SIBs demonstrated the lowest abiotic depletion potential and photochemical oxidation. However, they exhibited higher impacts in ozone depletion and eutrophication compared to liquid LIBs and liquid SIBs. Liquid LIBs showed the lowest global warming potential, making them more climate-friendly than the other battery types. Moreover, the results showed that, energetically, liquid LIBs are the most competitive option. To determine the conditions in which the solid SIBs improve the environmental behaviour of the liquid LIBs, an energetic and sensitivity analysis were conducted. Solid SIBs using renewable energy like concentrated solar power (CSP) and dematerializing part of its electrolyte exhibited reduced Cumulative Energy Demand and improved the environmental performance in all categories compared to conventional liquid LIBs. Furthermore, the study assessed the specific heat capacity (Cp) of the solid sodium electrolyte (NASICON), revealing its potential suitability for advanced battery technologies that require efficient heat storage and thermal management. Globally, this study highlights some environmental benefits of adopting solid SIBs, especially those manufactured with renewable energy, as a promising alternative to traditional lithium-ion batteries.

Based on the comparison of structures and properties of the HS6-5-2 high speed steels made with the powder injection moulding method, pressureless forming, compacting and sintering, and commercial steels made with the ASEA-STORA method, fine carbides spread evenly in the steel matrix were found in the structure of all tested high-speed steels in the sintered state. The use of a nitrogen atmosphere in the sintering process, causes the formation of fine, spherical MX type carbonitrides, stable in high sintering and austenitizing temperatures. The steels made with the pressureless forming method are characteristic of the lowest sintering temperature and the highest density, resulting from the high carbon concentration coming from the binding agent degradation. Moreover, the higher carbon concentration causes an increase in the retained austenite portion and a lower hardness after quenching and tempering. The heat-treated injection moulded steel attains hardness comparable to the commercial ASP23 type one, demonstrating the well-founded reasons for using the powder-injection moulding method for manufacturing the high-speed steel. The powder-injection moulding makes manufacturing tools possible with their final shape, i.e., leaving out the plastic forming and machining which is necessary for instance in case of the ASP 23 type steel. Furthermore, the degradation and sintering process time of the injection moulded steels is approximately 10h shorter than for steels made with pressureless moulding, which is due to the use of a two-component binding agent.

In this present investigation, Metal Injection Moulding (MIM) of M2 High Speed Steel (HSS) parts using a wax-High Density Polyethylene (HDPE) binder is shown. This work is focused on the examination of the sintering densification and microstructure evolution of the parts. The injection molding process of the feedstock has been optimized to obtain high quality green parts. The elimination of organic binder was carried out by thermal debinding under inert atmosphere. In order to keep carbon in the sample that could improve the sintering process, incomplete debinding was performed between 450 and 600 ºC. The specimens were sintered at temperatures between 1210 and 1280oC in high vacuum atmosphere, obtaining the 98% of the theoretical density. A homogeneous distribution of fine M6C carbides was obtained as well as V-rich carbides (MX) during sintering which reinforced the HSS and hence increasing the mechanical properties of the parts. In the samples with higher residual carbon content, the sintering window was extended up to 20 degrees and the optimum temperature was lower.

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Abstract: In this article, we present the evolution of the microstructure during sintering of M2 high speed steel (HSS) parts obtained by a modified powder injection molding (PIM) process, which uses a new binder system based on a thermosetting resin. The most important characteristics of this process is that molding is carried out at room temperature by pouring the slurry (resin and tool steel previously mixed) directly into the mold. The mold is then heated to the curing temperature of the resin. The best mixture of polymer and steel powders was 60 pct volume of metal powder. The resin was removed by thermal debinding. The sintering process was carried out under vacuum atmosphere. We tested different debinding temperatures in order to retain residual carbon in the samples coming from the thermal degradation of the polymer. The best results were obtained at low debinding temperature (300 C). In this case, residual carbon had a beneficial effect, extending the sintering temperature range by 100 deg, making it possible to reach very high density at temperatures as low as 1100 C. The mechanism of this densification seems to be via supersolidus liquid phase (SPLS). The microstructural study of sintered parts revealed a homogeneous distribution of carbides that change their morphology with increasing temperature. Besides spherical M6C carbides, which appear in all the temperature ranges studied, a new rodlike M2C carbide appears.

La_{2/3 − x}Li_3xTiO₃ (0 < x < 0.17) compounds have reached great prominence in the last few years due to their high lithium ion conductivity. They present a perovskite-related structure (ABO₃) with A-cation deficiency. However, neither the phase diagram nor the solidification processes are well known, which makes the growth of single crystals difficult. In this vein, we have processed La_0.5Li_0.5TiO₃ polycrystalline powder by the LFZ method and studied the processed material by means of SEM, EDS, XRD and micro-Raman techniques. Three phases have been detected: the major phase (A) is a La–Li–Ti–O perovskite with 3x < 0.5, that forms large single crystal grains. Phase B is rutile TiO₂ and appears as small precipitates surrounding phase A. Finally, we observe eutectic mixtures of phase A and a third phase (C) containing Ti and O in a ratio lower than 1∶2. Phase C is identified as a Li–Ti oxide, probably Li₂Ti₃O₇.

Li2Ti3O7, a ramsdellite-type compound, is able to reversibly insert approximately 2.3 lithium ions per formula down to 1 V versus lithium. Both electron and X-ray diffraction techniques show that the electrochemically inserted compounds Li2+xTi3O7, with x<2, maintain the ramsdellite structure, although some important microstructural differences are observed. For example the compound with x=0.55 exhibits an incommensurate modulation (q≈13c*). On the other hand, for Li2+xTi3O7with x>2, a commensurable a×2b×ccell can be proposed. A close structural relationship between the intercalated compounds and host compound, together with the small changes in the basic ramsdellite cell parameters during the intercalation process, is likely at the origin of the good cycling behavior of a lithium cell using Li2Ti3O7as the positive electrode.

A modified metal injection moulding (MIM) process of 316L stainless steels powders using an acrylic thermosetting resin has been developed. Gas and water atomised 316L powders were used. In order to optimise the mixing and moulding steps, different volume fractions of the two components were investigated. Mixing of metal powder and binder was carried out at room temperature and immediately moulding was performed by pouring the slurry in the moulds. It was then heated at 90°C to permit the polymerisation and cross linking of the resin. Different heating cycles, rates, and atmospheres were studied by means of thermogravimetrical analysis. The data obtained were used to establish the best debinding cycle. The debound samples were sintered at different temperatures and high densities (98% of theoretical) were obtained. Materials in as moulded (green part), debound (brown part), and sintered conditions were examined by means of SEM.

A microstructural study of the perovskite La_0.5Li_0.5TiO₃ is presented. A new, tetragonal cell, a = 2^1/2d_p and c = 2a_p, is proposed on the basis of the cubic perovskite subcell (a_p ~ 3.8 Å). By transmission electron microscopy a microdomain twinned structure has been observed. The twinning corresponds to the three possible orientations of the doubled c-axis. Besides these twinned domains, other domains have also been detected where fringe spacings corresponding to 2a_p × 2a_p are present. This seems to indicate the alternation of lanthanum and lithium along the [001] direction. Copyright 1995, 1999 Academic Press

The microstructural changes produced in the reaction of n-butyl-lithium with PrBa₂Cu₃O₇ have been followed by means of high resolution electron microscopy and electron diffraction. Extended defects are produced which have been interpreted on the basis of the Pr-124 structure. Although obtained in a disordered form, this is the first report on the pure, i.e., yttrium free PrBa₂Cu₄O₈ structure. Copyright 1994, 1999 Academic Press

Experiments on the chemical lithiation of Ba2YCu3O7and related materials have been performed previously by the authors [1–4]. One of the main results of that work is the room temperature formation of “124” from “123”. Here a simple ionic model is used to give an estimate of the activation energy for lithium motion which is in good agreement with experimental values obtained from conductivity measurements. Lithium diffusion seems to be favoured in the “124” compared with “123”. This result is discussed on the basis of the structure of these phases.

Room temperature reactions of n-butyllithium with either La2NiO4+yor the electrochemically oxidized La2CuO4+x(x=0.04, 0.08) have been performed. Neutron and X-ray diffraction experiments and magnetic susceptibility measurements indicate that the process which takes place in these cases is the reduction of the material by extraction of the interstitial oxygen rather than by the insertion of lithium within the structure.

Lithium cations sit in the center of the oxygen “windows” defined by the vertex-sharing TiO6 octahedra of the title compound (see picture), as shown from neutron diffraction data. The octahedra are tilted to optimize the bond distances between the atoms. The unusual coordination and the partially unoccupied sublattice (occupancy factors 1/6 and ½ for Li and La, respectively) account for the high mobility of the Li⁺ cations.

Lithiumionen befinden sich in der Mitte der Sauerstoff-“Fenster“ im Gerüst der eckenverknüpften TiO6-Oktaeder der Titelverbindung (siehe Bild), wie durch Neutronenbeugung gezeigt werden konnte. Die interatomaren Abstände werden dadurch optimiert, dass die Oktaeder etwas geneigt sind. Die ungewöhnliche Koordination und das teilweise unbesetzte Untergitter (Besetzungsfaktoren 1/6 und ½ für Li bzw. La) erklären die hohe Beweglichkeit der Lithiumionen.