Thermodynamic Property Study of Nanostructured Mg-H, Mg-Ni-H, and Mg-Cu-H Systems by High Pressure DSC Method

Mg, Ni, and Cu nanoparticles were synthesized by hydrogen plasma metal reaction method. Preparation of Mg2Ni and Mg2Cu alloys from these Mg, Ni, and Cu nanoparticles has been successfully achieved in convenient conditions. High pressure differential scanning calorimetry (DSC) technique in hydrogen atmosphere was applied to study the synthesis and thermodynamic properties of the hydrogen absorption/desorption processes of nanostructured Mg-H, Mg-Ni-H, and Mg-Cu-H systems. Van’t Hoff equation of Mg-Ni-H system as well as formation enthalpy and entropy of Mg2NiH4 was obtained by high pressure DSC method. The results agree with the ones by pressure-composition isotherm (PCT) methods in our previous work and the ones in literature

Facile Solvent-Free Synthesis of Anhydrous Alkali Metal Dodecaborate M_2B_(12)H_(12) (M = Li, Na, K)

Metal dodecaborate, widely regarded as an obstacle of the rehydrogenation of high-density hydrogen storage materials metal borohydrides M(BH_4)_n, is generally synthesized using liquid-phase process followed by a careful dehydration process. In this study, we propose a new and facile solvent-free synthesis process of dodecaborates using B_(10)H_(14) with a low melting point of 99.6 °C as a boron source. As a case study, our first challenge focused on the syntheses of anhydrous M_2B_(12)H_(12) (M = Li, Na, and K) by heat treatment of starting materials (a) 2MH + 1.2B_(10)H_(14) or (b) 2MBH_4 + B_(10)H_(14) at 200–450 °C conditions, which have been proved to be successful for the first time by X-ray diffraction (XRD), Raman, and NMR analysis. Starting materials (b) 2MBH_4 + B_(10)H_(14) shows better reactivity than that of (a) 2MH + 1.2B_(10)H_(14), which demonstrates that synthesis of anhydrous M_2B_(12)H_(12) by heat treatment of 2MBH_4 + B_(10)H_(14) is a feasible solvent-free process

Synthesis of a Bimetallic Dodecaborate LiNaB_(12)H_(12)with Outstanding Superionic Conductivity

Metal dodecaborates M_2/_nB_(12)H_(12) (n denotes the valence of the metal M), containing icosahedral polyatomic anion [B_(12)H_(12)]^(2−), have been attracting increasing interest as potential energy materials, especially in the context of hydrogen storage and superionic conductivity. M_2/_nB_(12)H_(12) are commonly formed as dehydrogenation intermediates from metal borohydrides M(BH_4)_n, like LiBH_4 and Mg(BH_4)_2, which are well-known as potential high-density hydrogen storage materials. The strong B−B bond in the icosahedral [B_(12)H_(12)]^(2−), however, is regarded to be the key factor that prevents the rehydrogenation of dodecaborates. In order to elucidate the mechanism as well as to provide effective solutions to this problem, a novel solvent-free synthesis route of anhydrous M_2/nB_(12)H_(12) (here M means Li, Na, and K) has been developed. Thermal stability and transformations of the anhydrous single phase Li_2B_(12)H_(12) suggested the formation of the high temperature polymorph of Li_2B_(12)H_(12) during the dehydrogenation of LiBH_4, while concurrently emphasized the importance of further investigation on the decomposition mechanism of metal borohydrides and metal dodecaborates. The high stability of icosahedral [B_(12)H_(12)]^(2−), on the other hand, favors its potential application as solid electrolyte. Recently, Na^+ conductivity of Na_2B_(12)H_(12) was reported to be 0.1 S/cm above its order−disorder phase transition at ∼529 K, which is comparable to that of a polycrystalline β”-Al_2O_3 (0.24 S/cm at 573 K) solid state Na-electrolyte. Mechanistic understanding on the diffusion behavior of cation and further improvement of ionic conductivity at a lower temperature, however, are important in order to facilitate the practical application of metal dodecaborates as superionic conductors

Design of a Nanometric AlTi Additive for MgB2-Based Reactive Hydride Composites with Superior Kinetic Properties

Solid-state hydride compounds are a promising option for efficient and safe hydrogen-storage systems. Lithium reactive hydride composite system 2LiBH4 + MgH2/2LiH + MgB2 (Li-RHC) has been widely investigated owing to its high theoretical hydrogen-storage capacity and low calculated reaction enthalpy (11.5 wt % H2 and 45.9 kJ/mol H2). In this paper, a thorough investigation into the effect of the formation of nano-TiAl alloys on the hydrogen-storage properties of Li-RHC is presented. The additive 3TiCl3·AlCl3 is used as the nanoparticle precursor. For the investigated temperatures and hydrogen pressures, the addition of ∼5 wt % 3TiCl3·AlCl3 leads to hydrogenation/dehydrogenation times of only 30 min and a reversible hydrogen-storage capacity of 9.5 wt %. The material containing 3TiCl3·AlCl3 possesses superior hydrogen-storage properties in terms of rates and a stable hydrogen capacity during several hydrogenation/dehydrogenation cycles. These enhancements are attributed to an in situ nanostructure and a hexagonal AlTi3 phase observed by high-resolution transmission electron microscopy. This phase acts in a 2-fold manner, first promoting the nucleation of MgB2 upon dehydrogenation and second suppressing the formation of Li2B12H12 upon hydrogenation/dehydrogenation cycling.Fil: Le, Thi-Thu. Helmholtz Zentrum Geesthacht; AlemaniaFil: Pistidda, Claudio. Helmholtz Zentrum Geesthacht; AlemaniaFil: Puszkiel, Julián Atilio. Helmholtz Zentrum Geesthacht; Alemania. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Castro Riglos, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Helmholtz Zentrum Geesthacht; Alemania. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Karimi, Fahim. Helmholtz Zentrum Geesthacht; AlemaniaFil: Skibsted, Jørgen. University Aarhus; DinamarcaFil: Gharibdoust, Seyedhosein Payandeh. University Aarhus; DinamarcaFil: Richter, Bo. University Aarhus; DinamarcaFil: Emmler, Thomas. Helmholtz Zentrum Geesthacht; AlemaniaFil: Milanese, Chiara. Università di Pavia; ItaliaFil: Santoru, Antonio. Helmholtz Zentrum Geesthacht; AlemaniaFil: Hoell, Armin. Helmholtz Zentrum Berlin für Materialien und Energie; AlemaniaFil: Krumrey, Michael. Physikalisch Technische Bundesanstalt; AlemaniaFil: Gericke, Eike. Universität zu Berlin; AlemaniaFil: Akiba, Etsuo. Kyushu University; JapónFil: Jensen, Torben R.. University Aarhus; DinamarcaFil: Klassen, Thomas. Helmholtz Zentrum Geesthacht; Alemania. Helmut Schmidt University; AlemaniaFil: Dornheim, Martin. Helmholtz Zentrum Geesthacht; Alemani

Research and development of hydrogen carrier based solutions for hydrogen compression and storage

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High-pressure torsion for new hydrogen storage materials

High-pressure torsion (HPT) is widely used as a severe plastic deformation technique to create ultrafine-grained structures with promising mechanical and functional properties. Since 2007, the method has been employed to enhance the hydrogenation kinetics in different Mg-based hydrogen storage materials. Recent studies showed that the method is effective not only for increasing the hydrogenation kinetics but also for improving the hydrogenation activity, for enhancing the air resistivity and more importantly for synthesizing new nanostructured hydrogen storage materials with high densities of lattice defects. This manuscript reviews some major findings on the impact of HPT process on the hydrogen storage performance of different titanium-based and magnesium-based materials