Studies of the effect of melt spinning on the electrochemical properties of the AB2 Laves phase alloys

A comparative study of the effect of melt spinning on the electrochemical properties of the C14 and C15 AB2 alloys has been performed. The wheel speeds of 630, 2100, and 4100 cm/s were applied during the rapid solidification of both alloys. The structural analysis of the formed phases was performed by X-ray powder diffraction (XRD), while their microstructural morphology was studied by scanning electron microscopy (SEM). In both alloys a tremendous grain refinement due to the melt spinning process was observed: In addition, melt spinning also significantly contributed to the morphological variation of the microstructural changes in C14 alloys which showed changes from the equiaxed grain at lower speed to the small dendrites at higher speed. In contrast to the C14 alloys, the morphological variation was not observed for the C15 alloys. Furthermore, for both C14 and C15 alloys melt-spun at 2100 cm/s the maximum capacities of 435 and 414 mAh/g were achieved, respectively. As both alloys revealed the significant grain refinement due to the melt spinning, an increase in electrochemical capacity was achieved. However, the melt spinning parameters need to be further optimized to improve poor activation behavior of the rapidly solidified alloys

Structural properties of mixed conductor Ba1−xGd1−yLax+yCo2O6−δ

BaGdLaCoO (BGLC) compositions with large compositional ranges of Ba, Gd, and La have been characterised with respect to phase compositions, structure, and thermal and chemical expansion. The results show a system with large compositional flexibility, enabling tuning of functional properties and thermal and chemical expansion. We show anisotropic chemical expansion and detailed refinements of emerging phases as La is substituted for Ba and Gd. The dominating phase is the double perovskite structure Pmmm, which is A-site ordered along the c-axes and with O vacancy ordering along the b-axis in the Ln-layer. Phases emerging when substituting La for Ba are orthorhombic Ba-deficient Pbnm and cubic LaCoO-based R3̄c. When La is almost completely substituted for Gd, the material can be stabilised in Pmmm, or cubic Pm3̄m, depending on thermal and atmospheric history. We list thermal expansion coefficients for x = 0-0.3, y = 0.2.The research has been supported by the National Science Centre Poland (2016/22/Z/ST5/00691), the Spanish Ministry of Science and Innovation (PCIN-2017-125, RTI2018-102161 and IJCI-2017-34110), and the Research Council of Norway (Grant no. 272797 “GoPHy MiCO”) through the M-ERA.NET Joint Call 2016. The authors acknowledge the skilful assistance from the staff of the Swiss–Norwegian Beamline (SNBL) at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. Dr. Cheng Li at POWGEN, SNS, Oak Ridge, US and Dr. Chiu C. Tang at beamline I11 at Diamond, Didcot, UK are gratefully acknowledged for PND and SR-PXD measurements, respectively

Hydrides of Laves type Ti–Zr alloys with enhanced H storage capacity as advanced metal hydride battery anodes

The present work was focused on the studies of the effect of variation of stoichiometric composition of Ti–Zr based AB2±x Laves phase alloys by changing the ratio between A (Ti + Zr) and B (Mn + V + Fe + Ni) components belonging to both hypo-stoichiometric (AB1.90, AB1.95) and over-stoichiometric (AB2.08) alloys further to the stoichiometric AB2.0 composition to optimize their hydrogen storage behaviours and performances as the alloy anodes of nickel metal hydride batteries. AB2-xLa0.03 Laves type alloys (A = Ti0.15Zr0.85; B = Mn0.64–0.69V0.11–0.119Fe0.11–0.119Ni1.097–1.184; x = 0, 0.05 and 0.1) were arc melted and then homogenized by annealing. The studies involved probing of the phase-structural composition by X-Ray diffraction (XRD), together with studies of the microstructural state, hydrogen absorption–desorption and thermodynamic characteristics of gas–solid reactions and electrochemical charge-discharge performance, further to the impedance spectroscopy characterization. The alloys were probed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and XRD. These studies concluded that the alloys contained the main C15 FCC Laves type AB2 intermetallic co-existing with a secondary C14 hexagonal Laves phase and a small amount of LaNi intermetallic

Application of hydrides in hydrogen storage and compression: Achievements, outlook and perspectives

Metal hydrides are known as a potential efficient, low-risk option for high-density hydrogen storage since the late 1970s. In this paper, the present status and the future perspectives of the use of metal hydrides for hydrogen storage are discussed. Since the early 1990s, interstitial metal hydrides are known as base materials for Ni – metal hydride rechargeable batteries. For hydrogen storage, metal hydride systems have been developed in the 2010s [1] for use in emergency or backup power units, i. e. for stationary applications. With the development and completion of the first submarines of the U212 A series by HDW (now Thyssen Krupp Marine Systems) in 2003 and its export class U214 in 2004, the use of metal hydrides for hydrogen storage in mobile applications has been established, with new application fields coming into focus. In the last decades, a huge number of new intermetallic and partially covalent hydrogen absorbing compounds has been identified and partly more, partly less extensively characterized. In addition, based on the thermodynamic properties of metal hydrides, this class of materials gives the opportunity to develop a new hydrogen compression technology. They allow the direct conversion from thermal energy into the compression of hydrogen gas without the need of any moving parts. Such compressors have been developed and are nowadays commercially available for pressures up to 200 bar. Metal hydride based compressors for higher pressures are under development. Moreover, storage systems consisting of the combination of metal hydrides and high-pressure vessels have been proposed as a realistic solution for on-board hydrogen storage on fuel cell vehicles. In the frame of the “Hydrogen Storage Systems for Mobile and Stationary Applications” Group in the International Energy Agency (IEA) Hydrogen Task 32 “Hydrogen-based energy storage”, different compounds have been and will be scaled-up in the near future and tested in the range of 500 g to several hundred kg for use in hydrogen storage applications.Fil: Bellosta von Colbe, Jose. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Ares Fernández, José Ramón. Universidad Autónoma de Madrid; EspañaFil: Jussara, Barale. Università di Torino; ItaliaFil: Baricco, Marcello. Università di Torino; ItaliaFil: Buckley, Craig E.. Curtin University; AustraliaFil: Capurso, Giovanni. Helmholtz Zentrum Geesthacht; AlemaniaFil: Gallandat, Noris. GRZ Technologies Ltd; SuizaFil: Grant, David M.. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino Unido. University of Nottingham; Estados UnidosFil: Guzik, Matylda N.. University of Oslo; NoruegaFil: Jacob, Isaac. Ben Gurion University of the Negev; IsraelFil: Jensen, Emil H.. University of Oslo; NoruegaFil: Jensen, Torben. University Aarhus; DinamarcaFil: Jepsen, Julian. Helmholtz Zentrum Geesthacht; AlemaniaFil: Klassen, Thomas. Helmholtz Zentrum Geesthacht; AlemaniaFil: Lototskyy, Mykhaylol V.. University of Cape Town; SudáfricaFil: Manickam, Kandavel. University of Nottingham; Estados Unidos. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino UnidoFil: Montone, Amelia. Casaccia Research Centre; ItaliaFil: Puszkiel, Julián Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Helmholtz Zentrum Geesthacht; AlemaniaFil: Sartori, Sabrina. University of Oslo; NoruegaFil: Sheppard, Drew A.. Curtin University; AustraliaFil: Stuart, Alastair. University of Nottingham; Estados Unidos. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino UnidoFil: Walker, Gavin. University of Nottingham; Estados Unidos. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino UnidoFil: Webb, Colin J.. Griffith University; AustraliaFil: Yang, Heena. Empa Materials Science & Technology; Suiza. École Polytechnique Fédérale de Lausanne; SuizaFil: Yartys, Volodymyr. Institute for Energy Technology; NoruegaFil: Züttel, Andreas. Empa Materials Science & Technology; Suiza. École Polytechnique Fédérale de Lausanne; SuizaFil: Dornheim, Martin. Helmholtz Zentrum Geesthacht; Alemani

Lightweight complex metal hydrides for Li-, Na-, and Mg-based batteries

Energy density and safety are the main factors that govern the development of the rechargeable battery technology. Currently, batteries beyond typical Li-ion batteries such as those based on solid-state electrolytes (SSEs) or other active elements (e.g., Na or Mg) are being examined as alternatives. For example, SSEs that would enable stable and reliable operation of all-solid-state Li-, Na-, and Mg-based batteries, with preferably improved capacity, are considered to be one of the most desired inventions. Lightweight complex metal hydrides are a family of solid compounds that were recently discovered to have extraordinary ionic conductivities and, in some cases, electrochemical properties that enabled battery reversibility. Consequently, they have become one of the promising electrolyte materials for future development of electrochemical storage devices. In this work, we present an overview of a wide range of lightweight hydride-based materials that could be used as electrolytes and/or anodes for mono-/divalent batteries and have a pivotal role in the implementation of new technological solutions in the field of electrochemistry

Effect of Al presence and synthesis method on phase composition of the hydrogen absorbing La–Mg–Ni-based compounds

Results for (La,Mg)Ni3.5 and (La,Mg)(Ni,Al)3.5 systems synthesized by metallurgical and mechanochemical techniques are reported. Powder X-ray and neutron diffraction combined with Rietveld refinements and profile analysis show that depending on the applied synthesis method various structurally related phases can be obtained for the same nominal composition. The hexagonal A2B7-type structure incorporating aluminum, with the refined composition La0.77Mg0.23Ni3.41Al0.09, has been identified. Al atoms occupy 12% of the 6h site within the LaNi5 slabs. This intermetallic phase absorbs hydrogen (deuterium) when exposed to 10 bar of H2 (D2) gas at room temperature. The H(D)-containing phase expands isotropically and retains the original symmetry of the parent compound. © 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0

Effect of ball milling and cryomilling on the microstructure and first hydrogenation properties of TiFe + 4 wt.% Zr alloy

In this paper, we report the microstructure and first hydrogenation properties of TiFe cast with 4 wt.% of Zr. Measurements were made in as-cast state and after processing by ball milling and cryomilling. It was found that ball milling and cryomilling significantly reduced the particle/crystallite sizes with most of the reduction occurring during the first 15 min of milling. While the cryomilled sample did not absorb any hydrogen, ball milling improved the initial kinetics of processed powders compared with the as-cast sample. However it also reduced the hydrogen storage capacity. The observed increased kinetics was likely caused by the reduction of crystallite sizes with longer ball milling times. However, the longer ball milling times might also be the reason of the capacity loss due to formation of new grain boundaries. Faster kinetics was not due to a change in the rate-limiting step, as all kinetics curves were fitted with the 3D growth, diffusion controlled with decreasing interface velocity model

Stability and Phase Formation in the (Li/Na)6C60–H Systems Studied by Neutron Scattering

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Half-Heusler Phase Formation and Ni Atom Distribution in M-Ni-Sn (M = Hf, Ti, Zr) systems

acceptedVersio