Recent Progress in Metal Borohydrides for Hydrogen Storage

Li, Haiwen; Yan, Yigang; Orimo, Shin Ichi; Züttel, Andreas; Jensen, Craig M.

doi:10.3390/en4010185

Cited by 441 publications

(459 citation statements)

References 227 publications

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“…S5). The slope of the first peak in the B K-edge of LiBH 4 -C deh is strongly linked to the content of boron powder and the height of the XRS peak is connected to the Li 2 4 to carbon via reaction eqn (3a). The Li K-edge XRS could as well be informative on this aspect, since whenever boron is present also LiH or Li in some form should be present.…”

Section: Resultsmentioning

confidence: 99%

“…This type of preparation was published before by He et al 22 The XRD pattern of the Li 2 B 12 H 12 prepared in the way mentioned above is shown besides the starting components in the ESI † (Fig. S1) and it shows a Bragg peak around 18 degrees which is observed as well in the Li 2 All samples preparations and handling was conducted in an argon filled glove box (typically o1 ppm of oxygen and moisture) to avoid contamination. All prepared samples and reference materials mentioned above were sent to the Stanford Synchrotron Radiation Lightsource (SSRL) in an air-tight container and directly brought into an argon filled glove box present at the SSRL.…”

Section: Preparation Of LImentioning

confidence: 96%

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In situ X-ray Raman spectroscopy study of the hydrogen sorption properties of lithium borohydride nanocomposites

Miedema

Ngene

Eerden

et al. 2014

Phys. Chem. Chem. Phys.

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Nanoconfined alkali metal borohydrides are promising materials for reversible hydrogen storage applications, but the characterization of hydrogen sorption in these materials is difficult. Here we show that with in situ X-ray Raman spectroscopy (XRS) we can track the relative amounts of intermediates and final products formed during de-and re-hydrogenation of nanoconfined lithium borohydride (LiBH 4 ) and therefore we can possibly identify the de-and re-hydrogenation pathways. In the XRS of nanoconfined LiBH 4 at different points in the de-and re-hydrogenation, we identified phases that lead to the conclusion that de-and re-hydrogenation pathways in nanoconfined LiBH 4 are different from bulk LiBH 4 : intercalated lithium (LiC x ), boron and lithium hydride were formed during de-hydrogenation, but as well Li 2 B 12 H 12 was observed indicating that there is possibly some bulk LiBH 4 present in the nanoconfined sample LiBH 4 -C as prepared.Surprisingly, XRS revealed that the de-hydrogenated products of the LiBH 4 -C nanocomposites can be partially rehydrogenated to about 90% of Li 2 B 12 H 12 and 2-5% of LiBH 4 at a mild condition of 1 bar H 2 and 350 1C. This suggests that re-hydrogenation occurs via the formation of Li 2 B 12 H 12 . Our results show that XRS is an elegant technique that can be used for in and ex situ study of the hydrogen sorption properties of nanoconfined and bulk light-weight metal hydrides in energy storage applications.

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Section: Resultsmentioning

confidence: 99%

Section: Preparation Of LImentioning

confidence: 96%

In situ X-ray Raman spectroscopy study of the hydrogen sorption properties of lithium borohydride nanocomposites

Miedema

Ngene

Eerden

et al. 2014

Phys. Chem. Chem. Phys.

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“…1 Recently, 15 there has also been reported high Li-ion conductivity in several Li-containing borohydrides, such as ortho-LiBH 4 2 and LiCe(BH 4 ) 3 Cl, 3 which makes them interesting as solid electrolytes in Li-ion batteries. Partial substitution of the tetraborohydride anions (BH 4 -) with heavy halides (Cl -, Br -or I -) 20 has been successfully used to alter the properties of borohydrides, e.g.…”

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confidence: 99%

Structural and spectroscopic characterization of potassium fluoroborohydrides

Heyn

Saldan

Sørby

et al. 2013

Phys. Chem. Chem. Phys.

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Metal borohydrides are intensively investigated in the context of energy storage due to their high hydrogen content. 1 Recently, 15 there has also been reported high Li-ion conductivity in several Li-containing borohydrides, such as ortho-LiBH 4 2 and LiCe(BH 4 ) 3 Cl, 3 which makes them interesting as solid electrolytes in Li-ion batteries. Partial substitution of the tetraborohydride anions (BH 4 -) with heavy halides (Cl -, Br -or I -) 20 has been successfully used to alter the properties of borohydrides, e.g. to stabilize the Li-conducting, high-temperature ortho-LiBH 4 phase at room temperature. [4][5][6][7][8] However, the inclusion of heavy halides has only a minor effect on the temperature of hydrogen desorption, 9,10 which must be significantly lowered for alkali-and 25 alkaline earth borohydrides to become viable hydrogen storage materials. For alanates, substitution of hydrogen with fluorine has shown a large effect on the thermal stability, 11 and substitution of F -anions into LiBH 4 has been recently shown theoretically to result in materials with favorable thermodynamics for onboard 30 hydrogen storage applications. 12 Despite the chemical similarity between hydrides and fluorides, there is only one report of confirmed fluorine substitution in borohydrides. 13 An earlier report only presumes the formation of a fluoroborohydride. 14 The present paper reports the results from ball milling of 35 mixtures of KBH 4 and KBF 4 in the molar ratios 3:1 and 1:1 (samples 1 and 2, respectively). The mixtures were milled for 10 hours at ambient temperature. The powder X-ray diffraction (PXD) patterns of the milled products resembled that for pure KBH 4 (CsClO 4 -type structure, space group Fm-3m), but with 40 appreciable shifts in the Bragg peak positions to lower angles, thus indicating expansion of the unit cells. This is consistent with substitution of larger BF 4 -tetrahedra for BH 4 -tetrahedra or larger fluorine atoms for hydrogen. No Bragg peaks for KBF 4 (orthorhombic, BaSO 4 -type structure) were observed. 45The PXD data were analysed using the Rietveld method. The Rietveld fits for 1 and 2 are shown in Figures 1 and 2, respectively. The KBH 4 structure 15 was taken as the starting point. The K and B sublattices together form a NaCl-type structure. The B positions are cubically coordinated by 8 half- Table 1. The unit cell parameters of 1 and 2 were 6.8174(2) Å and 6.9219(9) Å, respectively, compared to 6.7280(8) Å for pure KBH 4 . 15 Thus, the unit cell a axis increases 65 linearly with the amount of fluorine in the sample; this is consistent with the existence of a solid solution. Moreover, the refined compositions of the 3:1 and 1:1 phases are close to the nominal compositions (see Table 1). Refinements with the phase compositions fixed at the nominal compositions gave little or no 70 change in the R-factor (R wp = 4.86% for 1 and unchanged for 2). These findings point towards a complete incorporation of the fluoride into the KBH 4 phase; the nominal compositions are therefore used i...

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“…For these reasons, several attempts have been recently carried out in order to promote hydrogen desorption and absorption processes. Because electronic structure calculations indicate that a charge transfer from the metal cations M n þ to the [BH 4 ] anions is a key feature determining the thermodynamic stability of M(BH 4 ) n , cation and anion substitutions in LiBH 4 have been investigated [3][4][5][6][7]. Moreover, a destablization of LiBH 4 via reaction with a second hydride system has been suggested, in order to reduce the Gibbs Free Energy (GFE) difference between hydrogenated and de-hydrogenated species [2,8].…”

Section: Introductionmentioning

confidence: 99%

A thermodynamic assessment of LiBH4

Kharbachi

Pinatel

Nuta

et al. 2012

Calphad

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a b s t r a c t Thermodynamic data of the LiBH 4 compound are reviewed and critically assessed. On the basis of literature data of heat capacity, heat of formation, temperature and enthalpy of phase transitions, a CALPHAD optimized Gibbs energy function is derived for the condensed phases i.e. orthorhombic and hexagonal solid phases and the liquid phase. Considering hydrogen as an ideal gas phase, the thermodynamics of decomposition reactions of LiBH 4 is calculated, showing good agreement with existing experimental data.

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Recent Progress in Metal Borohydrides for Hydrogen Storage

Cited by 441 publications

References 227 publications

In situ X-ray Raman spectroscopy study of the hydrogen sorption properties of lithium borohydride nanocomposites

In situ X-ray Raman spectroscopy study of the hydrogen sorption properties of lithium borohydride nanocomposites

Structural and spectroscopic characterization of potassium fluoroborohydrides

A thermodynamic assessment of LiBH4

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