Dehydrogenation Reaction Pathway of the LiBH<sub>4</sub>–MgH<sub>2</sub> Composite under Various Pressure Conditions

Kim, Kee-Bum; Shim, Jaesool; Park, So‐Hyun; Choi, In‐Suk; Oh, Kyu Hwan; Cho, Young Whan

doi:10.1021/jp5123757

Cited by 40 publications

(28 citation statements)

References 38 publications

(74 reference statements)

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“…[6,11,12] Downsizing materials to the nanometer scale has been extensively demonstrated to relieve the inherent limitations to the diffusion of elements in the solid state and facilitate destabilization induced by excess surface energy. [13][14][15] Due to the high reactivity of both LiBH4 and MgH2, the synthetic strategy of direct synthesis of the 2LiBH4-MgH2 composite is limited to mechanical milling with uncontrollable size distribution, and, meanwhile, the performance of the mechanically milled composite is degraded during high-temperature cycling, mainly due to the uncontrolled particle growth and/or the aggregation during cycles of hydrogenation and dehydrogenation.…”

Section: Introductionmentioning

confidence: 99%

Graphene-wrapped reversible reaction for advanced hydrogen storage

Xia

Tan

et al. 2016

Nano Energy

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X. (2016). Graphene-wrapped reversible reaction for advanced hydrogen storage. Nano Energy, 26 488-495. Graphene-wrapped reversible reaction for advanced hydrogen storage AbstractHere, we report the fabrication of a graphene-wrapped nanostructured reactive hydride composite, i.e., 2LiBH4-MgH2, made by adopting graphene-supported MgH2 nanoparticles (NPs) as the nanoreactor and heterogeneous nucleation sites. The porous structure, uniform distribution of MgH2 NPs, and the steric confinement by flexible graphene induced a homogeneous distribution of 2LiBH4-MgH2 nanocomposite on graphene with extremely high loading capacity (80 wt%) and energy density. The well-defined structural features, including even distribution, uniform particle size, excellent thermal stability, and robust architecture endow this composite with significant improvements in its hydrogen storage performance. For instance, at a temperature as low as 350 °C, a reversible storage capacity of up to 8.9 wt% H2, without degradation after 25 complete cycles, was achieved for the 2LiBH4-MgH2 anchored on graphene. The design of this threedimensional architecture can offer a new concept for obtaining high performance materials in the energy storage field. AbstractHere, we report the fabrication of a graphene-wrapped nanostructured reactive hydride composite, i.e., 2LiBH4-MgH2, made by adopting graphene-supported MgH2 nanoparticles (NPs) as the nanoreactor and heterogeneous nucleation sites. The porous structure, uniform distribution of MgH2 NPs, and the steric confinement by flexible graphene induced a homogeneous distribution of 2LiBH4-MgH2 nanocomposite on graphene with extremely high loading capacity (80 wt%) and energy density. The well-defined structural features, including even distribution, uniform particle size, excellent thermal stability, and robust architecture endow this composite with significant improvements in its hydrogen storage performance. For instance, at a temperature as low as 350 o C, a reversible storage capacity of up to 8.9wt.% H2, without degradation after 25 complete cycles, was achieved for the 2LiBH 4 -MgH 2 anchored on graphene. The design of this three-dimensional architecture can offer a new concept for obtaining high performance materials in the energy storage field.

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Section: Introductionmentioning

confidence: 99%

Graphene-wrapped reversible reaction for advanced hydrogen storage

Xia

Tan

et al. 2016

Nano Energy

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“…The dehydrogenations of the 2LiBH 4 + Al, 2LiBH 4 + Al/TiF 3 , and 2LiBH 4 + Al/CeO 2 materials are multi-step reactions. The multistep nature of the dehydrogenation reaction of the 2LiBH 4 + Al is shared with the dehydrogenation of LiBH 4 [36] and the RHC LiBH 4 + MgH 2 [22,37]. Reports of LiBH 4 -Al dehydrogenation in several molar proportions also described a multistep mechanism for the dehydrogenation reaction [17,[19][20][21]38].…”

Section: Discussionmentioning

confidence: 95%

Dehydrogenation of Surface-Oxidized Mixtures of 2LiBH4 + Al/Additives (TiF3 or CeO2)

2017

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Abstract:Research for suitable hydrogen storage materials is an important ongoing subject. LiBH 4 -Al mixtures could be attractive; however, several issues must be solved. Here, the dehydrogenation reactions of surface-oxidized 2LiBH 4 + Al mixtures plus an additive (TiF 3 or CeO 2 ) at two different pressures are presented. The mixtures were produced by mechanical milling and handled under welding-grade argon. The dehydrogenation reactions were studied by means of temperature programmed desorption (TPD) at 400 • C and at 3 or 5 bar initial hydrogen pressure. The milled and dehydrogenated materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transformed infrared spectroscopy (FT-IR) The additives and the surface oxidation, promoted by the impurities in the welding-grade argon, induced a reduction in the dehydrogenation temperature and an increase in the reaction kinetics, as compared to pure (reported) LiBH 4 . The dehydrogenation reactions were observed to take place in two main steps, with onsets at 100 • C and 200-300 • C. The maximum released hydrogen was 9.3 wt % in the 2LiBH 4 + Al/TiF 3 material, and 7.9 wt % in the 2LiBH 4 + Al/CeO 2 material. Formation of CeB 6 after dehydrogenation of 2LiBH 4 + Al/CeO 2 was confirmed.

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“…For example, for x = 0.5 composite, all the H 2 (6 mass %) was released in the temperature range 580 K to 630 K in the TG-MS experiments. However, an initial backpressure of at least 0.5 MPa H 2 is needed for the incubation of the composite reaction between LiBH 4 and MgH 2 [31,32]. Also, the dehydrogenation process of the composite material of LiBH 4 and Mg 2 NiH 4 separated into more than three reactions and lasted from room temperature to beyond 673 K [6].…”

Section: Discussionmentioning

confidence: 99%

Thermodynamic Properties and Reversible Hydrogenation of LiBH4–Mg2FeH6 Composite Materials

Matsuo

Takagi

et al. 2017

Inorganics

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Abstract:In previous studies, complex hydrides LiBH 4 and Mg 2 FeH 6 have been reported to undergo simultaneous dehydrogenation when ball-milled as composite materials (1 − x)LiBH 4 + xMg 2 FeH 6 . The simultaneous hydrogen release led to a decrease of the dehydrogenation temperature by as much as 150 K when compared to that of LiBH 4 . It also led to the modified dehydrogenation properties of Mg 2 FeH 6 . The simultaneous dehydrogenation behavior between stoichiometric ratios of LiBH 4 and Mg 2 FeH 6 is not yet understood. Therefore, in the present work, we used the molar ratio x = 0.25, 0.5, and 0.75, and studied the isothermal dehydrogenation processes via pressure-composition-isothermal (PCT) measurements. The results indicated that the same stoichiometric reaction occurred in all of these composite materials, and x = 0.5 was the molar ratio between LiBH 4 and Mg 2 FeH 6 in the reaction. Due to the optimal composition ratio, the composite material exhibited enhanced rehydrogenation and reversibility properties: the temperature and pressure of 673 K and 20 MPa of H 2 , respectively, for the full rehydrogenation of x = 0.5 composite, were much lower than those required for the partial rehydrogenation of LiBH 4 . Moreover, the x = 0.5 composite could be reversibly hydrogenated for more than four cycles without degradation of its H 2 capacity.

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Dehydrogenation Reaction Pathway of the LiBH₄–MgH₂ Composite under Various Pressure Conditions

Cited by 40 publications

References 38 publications

Graphene-wrapped reversible reaction for advanced hydrogen storage

Graphene-wrapped reversible reaction for advanced hydrogen storage

Dehydrogenation of Surface-Oxidized Mixtures of 2LiBH4 + Al/Additives (TiF3 or CeO2)

Thermodynamic Properties and Reversible Hydrogenation of LiBH4–Mg2FeH6 Composite Materials

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Dehydrogenation Reaction Pathway of the LiBH4–MgH2 Composite under Various Pressure Conditions

Cited by 40 publications

References 38 publications

Graphene-wrapped reversible reaction for advanced hydrogen storage

Graphene-wrapped reversible reaction for advanced hydrogen storage

Dehydrogenation of Surface-Oxidized Mixtures of 2LiBH4 + Al/Additives (TiF3 or CeO2)

Thermodynamic Properties and Reversible Hydrogenation of LiBH4–Mg2FeH6 Composite Materials

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Dehydrogenation Reaction Pathway of the LiBH₄–MgH₂ Composite under Various Pressure Conditions