Synthesis, Crystal Structure, and Thermal Properties of the First Mixed-Metal and Anion-Substituted Rare Earth Borohydride LiCe(BH<sub>4</sub>)<sub>3</sub>Cl

Frommen, Christoph; Sørby, Magnus H.; Ravindran, P.; Vajeeston, Ponniah; Fjellvåg, Helmer; Hauback, Bjørn C.

doi:10.1021/jp205105j

Cited by 50 publications

(69 citation statements)

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“…A similar situation was previously observed for LiCe(BH4)3Cl, where partial reversibility was observed and was attributed to CeH2. 2 Mixed phases ultimately reduce the hydrogen capacity of these materials and inhibit the reversible hydrogenation of these borohydrides due to the formation of side products. Another factor that affects the reversibility of the material is the evolution of B2H6 during decomposition, as observed by MS analysis.…”

Section: Discussionmentioning

confidence: 99%

Crystal structure and in situ decomposition of Eu(BH₄)₂ and Sm(BH₄)₂

et al. 2015

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Synthesis of halide free rare earth metal (RE) borohydride complexes is demonstrated by the metathesis reaction of trivalent RE metal chlorides and LiBH4 in ethereal solution, combined with solvent extraction with dimethyl sulfide. The crystal structures of Eu(BH4)2 and Sm(BH4)2 are orthorhombic (space group Pbcn) and are shown to be related to the structure of Sr(BH4)2 by Rietveld refinement. Further, the thermal decomposition of these materials has been studied by in situ synchrotron radiation powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, mass spectrometry and Sieverts measurements. The decomposition pathway of these solvent extracted materials has been compared against materials prepared by mechano-chemistry; the process of which is simplified by the absence of chloride impurities, promoting partial reversible hydrogenation of these systems. IntroductionThe research and development of renewable energies, alternative fuels and new methods for energy storage and conversion have become part of many countries' political and scientific discourse. Hydrogen is the lightest element of all with the highest gravimetric energy density, and is considered one of the most promising options to store the extreme amounts of energy that must be harvested to level out the strongly fluctuating renewable sources such as solar and wind energy. 1 A host of rare earth metal (RE) borohydrides have recently been identified and structurally investigated, some of which may act as hydrogen storage materials or new multifunctional materials. [2][3][4][5][6][7][8][9][10] The hydrogen content of rare earth metal borohydrides (e.g. rm(Y(BH4)3) = 9.0 wt% H) is highly acceptable in regards to more established materials such as NaAlH4 (7.5 wt% H), and initial studies have determined that thermal decomposition initiates at moderate temperatures (190 °C) producing high purity H2.11 In addition, their optical and magnetic properties and most recently their electrochemical properties have been investigated for new potential applications. [12][13][14][15] The new series of isostructural materials LiM(BH4)3Cl (M = La, Ce, Nd, Sm, Gd or Yb) store hydrogen and are simultaneous fast lithium ion conductors.2-6 These materials have a fascinating structure, containing isolated tetranuclear anionic clusters, e.g. [Ce4Cl4(BH4)12] 4− with a distorted cubane Ce4Cl4 core and are charge-balanced by disordered Li + cations occupying 2/3 of the available positions. The synthesis of the transition metal (TM) and RE borohydrides has traditionally been via mechano-chemically facilitated metathesis reactions using alkali metal borohydrides (Li, Na, K) and metal chlorides. 2,8,16 This usually leads to the formation of mixed-metal and often anion-substituted borohydrides such as NaSc(BH4)4, LiCe(BH4)3Cl or solid solutions such as Na(BH4)xCl1−x. 2,5,17,18 The halide side product is often difficult to remove and may hinder the reversible hydrogenation of the metal borohydride due to formation of ternary chlorides. The solvent m...

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Section: Discussionmentioning

confidence: 99%

Crystal structure and in situ decomposition of Eu(BH₄)₂ and Sm(BH₄)₂

et al. 2015

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“…However, it requires very tough conditions for rehydrogenation [3] and suffers from capacity loss on cycling due to the formation of higher boranes [4]. Another class of materials to be considered is rare earth (RE) borohydrides, with hydrogen capacities varying between 9.0 wt % for Y(BH 4 ) 3 and 5.5 wt % for Yb(BH 4 ) 3 [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Li-containing RE borohydrides are also considered as solid state electrolytes for new battery applications, due to their high Li-ion conductivities [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Sorption in Erbium Borohydride Composite Mixtures with LiBH4 and/or LiH

et al. 2017

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Rare earth (RE) metal borohydrides have recently been receiving attention as possible hydrogen storage materials and solid-state Li-ion conductors. In this paper, the decomposition and reabsorption of Er(BH 4 ) 3 in composite mixtures with LiBH 4 and/or LiH were investigated. The composite of 3LiBH 4 + Er(BH 4 ) 3 + 3LiH has a theoretical hydrogen storage capacity of 9 wt %, nevertheless, only 6 wt % hydrogen are accessible due to the formation of thermally stable LiH. Hydrogen sorption measurements in a Sieverts-type apparatus revealed that during three desorption-absorption cycles of 3LiBH 4 + Er(BH 4 ) 3 + 3LiH, the composite desorbed 4.2, 3.7 and 3.5 wt % H for the first, second and third cycle, respectively, and thus showed good rehydrogenation behavior. In situ synchrotron radiation powder X-ray diffraction (SR-PXD) after ball milling of Er(BH 4 ) 3 + 6LiH resulted in the formation of LiBH 4 , revealing that metathesis reactions occurred during milling in these systems. Impedance spectroscopy of absorbed Er(BH 4 ) 3 + 6LiH showed an exceptional high hysteresis of 40-60 K for the transition between the high and low temperature phases of LiBH 4 , indicating that the high temperature phase of LiBH 4 is stabilized in the composite.

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“…Since the first report [4], anion substitution has been suggested as a promising method to favor the thermodynamics of hydrogen sorption in complex hydrides [5][6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Theoretical and experimental study on Mg(BH4)2–Zn(BH4)2 mixed borohydrides

Albanese

Kalantzopoulos

Vitillo

et al. 2013

Journal of Alloys and Compounds

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After a screening of possible systems prone to give an enthalpy of decomposition close to 30 kJ·mol -1 H2 , i.e. suitable for a dehydrogenation process close to room temperature and pressure, the Zn dissolution into Mg(BH 4 ) 2 has been investigated. The total energy of pure compounds and solid solutions has been computed by DFT calculations using the CRYSTAL09 code. The phase mixture obtained after the synthesis strongly depends on the milling conditions. For prolonged times, the formation of Zn and MgCl 2 has been observed, suggesting the delivering of B-containing species during the milling. After heating, a hydrogen release, coupled with diborane delivering, has been observed for temperatures close to 100 °C, suggesting a significant decrease of the decomposition temperature with respect to pure Mg(BH 4 ) 2 . Theoretical and experimental results have been discussed on the basis of the possibile reaction paths, as estimated from available thermodynamic databases.

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Synthesis, Crystal Structure, and Thermal Properties of the First Mixed-Metal and Anion-Substituted Rare Earth Borohydride LiCe(BH₄)₃Cl

Abstract: The mechanochemical reaction between LiBH 4 and CeCl 3 in a molar ratio of 3:1 has led to the formation of LiCe(BH 4 ) 3 Cl. This compound is the first example of a mixed-metal

Cited by 50 publications

References 48 publications

Crystal structure and in situ decomposition of Eu(BH₄)₂ and Sm(BH₄)₂

Crystal structure and in situ decomposition of Eu(BH₄)₂ and Sm(BH₄)₂

Hydrogen Sorption in Erbium Borohydride Composite Mixtures with LiBH4 and/or LiH

Theoretical and experimental study on Mg(BH4)2–Zn(BH4)2 mixed borohydrides

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Synthesis, Crystal Structure, and Thermal Properties of the First Mixed-Metal and Anion-Substituted Rare Earth Borohydride LiCe(BH4)3Cl

Abstract: The mechanochemical reaction between LiBH 4 and CeCl 3 in a molar ratio of 3:1 has led to the formation of LiCe(BH 4 ) 3 Cl. This compound is the first example of a mixed-metal

Cited by 50 publications

References 48 publications

Crystal structure and in situ decomposition of Eu(BH4)2 and Sm(BH4)2

Crystal structure and in situ decomposition of Eu(BH4)2 and Sm(BH4)2

Hydrogen Sorption in Erbium Borohydride Composite Mixtures with LiBH4 and/or LiH

Theoretical and experimental study on Mg(BH4)2–Zn(BH4)2 mixed borohydrides

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Product

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Synthesis, Crystal Structure, and Thermal Properties of the First Mixed-Metal and Anion-Substituted Rare Earth Borohydride LiCe(BH₄)₃Cl

Crystal structure and in situ decomposition of Eu(BH₄)₂ and Sm(BH₄)₂

Crystal structure and in situ decomposition of Eu(BH₄)₂ and Sm(BH₄)₂