Thermodynamic and kinetic investigations of the hydrogen storage in the Li–Mg–N–H system

Xiong, Zhitao; Hu, Jianjiang; Wu, Guotao; Chen, Ping; Luo, Wei; Gross, Karl; Wang, James

doi:10.1016/j.jallcom.2005.02.010

Cited by 259 publications

(275 citation statements)

References 23 publications

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“…As mentioned above, there are two proposals for the dehydrogenation mechanism. Regardless of which mechanism plays the main role, there will be dissociation of the chemical bonds (e.g., NÀH, MgÀN, or LiÀH) of the reactants and the evolution of intermediates (e.g., gas intermediate NH 3 [17][18][19] or complex solid intermediates [15,20,36] ). Therefore, by activating each component of this composite deliberately and looking at the changes in the reaction kinetics, we may be able to clarify the origin of the kinetic barrier.…”

Section: Resultsmentioning

confidence: 99%

“…[15,20,21] According to the proposed mechanism, the reaction rate may be controlled by the interface reaction at the early stage of dehydrogenation and by mass transfer in the later stage. [20] For mass transportation, the mobility of ions in the phases of the reactant (amide) and product (imide) are likely to play a key role.…”

Section: Full Papersmentioning

confidence: 99%

“…[15] However, dehydrogenation at an appropriate rate usually requires temperatures above 180 8C even if the composite has undergone intensive ball milling, which shows the existence of a severe kinetic barrier in the dehydrogenation. A number of mechanistic investigations have been conducted, which have controversial interpretations.…”

Section: Introductionmentioning

confidence: 99%

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Solid–Solid Heterogeneous Catalysis: The Role of Potassium in Promoting the Dehydrogenation of the Mg(NH₂)₂/2 LiH Composite

et al. 2013

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Considerable efforts have been devoted to the catalytic modification of hydrogen storage materials. The K‐modified Mg(NH2)2/2 LiH composite is a typical model for such studies. In this work, we analyze the origin of the kinetic barrier in the first step of the dehydrogenation and investigate how K catalyzes this heterogeneous solid‐state reaction. Our results indicate that the interface reaction of Mg(NH2)2 and LiH is the main source of the kinetic barrier at the early stage of the dehydrogenation for the intensively ball‐milled Mg(NH2)2/2 LiH sample. K can effectively activate Mg(NH2)2 as well as promote LiH to participate in the dehydrogenation. Three K species of KH, K2Mg(NH2)4, and Li3K(NH2)4 likely transform circularly in the dehydrogenation (KH↔K2Mg(NH2)4↔KLi3(NH2)4), which creates a more energy‐favorable pathway and thus leads to the overall kinetic enhancement. This catalytic role of K in the amide/hydride system is different from the conventional catalysis of transition metals in the alanate system.

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Section: Resultsmentioning

confidence: 99%

Section: Full Papersmentioning

confidence: 99%

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Solid–Solid Heterogeneous Catalysis: The Role of Potassium in Promoting the Dehydrogenation of the Mg(NH₂)₂/2 LiH Composite

et al. 2013

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“…Considering that this step is accompanied by release of ammonia and kinetic constraints, starting from the Mg(NH 2 ) 2 + 2LiH system is more advisable. One of the first studies on Mg(NH 2 ) 2 + 2LiH was reported by Xiong et al [79] in 2005. The reactants, ball-milled together for 48 h, upon dehydrogenation at 250 • C release a considerable amount of hydrogen (5.0 wt.…”

Section: Li-mg-n-h Systemmentioning

confidence: 99%

Recent Progress and New Perspectives on Metal Amide and Imide Systems for Solid-State Hydrogen Storage

et al. 2018

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Hydrogen storage in the solid state represents one of the most attractive and challenging ways to supply hydrogen to a proton exchange membrane (PEM) fuel cell. Although in the last 15 years a large variety of material systems have been identified as possible candidates for storing hydrogen, further efforts have to be made in the development of systems which meet the strict targets of the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) and U.S. Department of Energy (DOE). Recent projections indicate that a system possessing: (i) an ideal enthalpy in the range of 20-50 kJ/mol H 2 , to use the heat produced by PEM fuel cell for providing the energy necessary for desorption; (ii) a gravimetric hydrogen density of 5 wt. % H 2 and (iii) fast sorption kinetics below 110 • C is strongly recommended. Among the known hydrogen storage materials, amide and imide-based mixtures represent the most promising class of compounds for on-board applications; however, some barriers still have to be overcome before considering this class of material mature for real applications. In this review, the most relevant progresses made in the recent years as well as the kinetic and thermodynamic properties, experimentally measured for the most promising systems, are reported and properly discussed.

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“…[16][17][18] Thermodynamically, it predicts a dissociation pressure of 0.1 MPa at $90 C. 17 However, two barriers still remain for the potential application of this system. 19 On the one hand, the dehydrogenation reaction is kinetically limited.…”

Section: Introductionmentioning

confidence: 99%

Effect of Li₃N additive on the hydrogen storage properties of Li-Mg-N-H system

Fang

Dai

et al. 2009

J. Mater. Res.

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The effect of Li 3 N additive on the Li-Mg-N-H system was examined with respect to the reversible dehydrogenation performance. Screening study with varying Li 3 N additions (5, 10, 20, and 30 mol%) demonstrates that all are effective for improving the hydrogen desorption capacity. Optimally, incorporation of 10 mol% Li 3 N improves the practical capacity from 3.9 wt% to approximately 4.7 wt% hydrogen at 200 C, which drives the dehydrogenation reaction toward completion. Moreover, the capacity enhancement persists well over 10 de-/rehydrogenation cycles. Systematic x-ray diffraction examinations indicate that Li 3 N additive transforms into LiNH 2 and LiH phases and remains during hydrogen cycling. Combined structure/property investigations suggest that the LiNH 2 "seeding" should be responsible for the capacity enhancement, which reduces the kinetic barrier associated with the nucleation of intermediate LiNH 2 . In addition, the concurrent incorporation of LiH is effective for mitigating the ammonia release.

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Thermodynamic and kinetic investigations of the hydrogen storage in the Li–Mg–N–H system

Cited by 259 publications

References 23 publications

Solid–Solid Heterogeneous Catalysis: The Role of Potassium in Promoting the Dehydrogenation of the Mg(NH₂)₂/2 LiH Composite

Solid–Solid Heterogeneous Catalysis: The Role of Potassium in Promoting the Dehydrogenation of the Mg(NH₂)₂/2 LiH Composite

Recent Progress and New Perspectives on Metal Amide and Imide Systems for Solid-State Hydrogen Storage

Effect of Li₃N additive on the hydrogen storage properties of Li-Mg-N-H system

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Thermodynamic and kinetic investigations of the hydrogen storage in the Li–Mg–N–H system

Cited by 259 publications

References 23 publications

Solid–Solid Heterogeneous Catalysis: The Role of Potassium in Promoting the Dehydrogenation of the Mg(NH2)2/2 LiH Composite

Solid–Solid Heterogeneous Catalysis: The Role of Potassium in Promoting the Dehydrogenation of the Mg(NH2)2/2 LiH Composite

Recent Progress and New Perspectives on Metal Amide and Imide Systems for Solid-State Hydrogen Storage

Effect of Li3N additive on the hydrogen storage properties of Li-Mg-N-H system

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Solid–Solid Heterogeneous Catalysis: The Role of Potassium in Promoting the Dehydrogenation of the Mg(NH₂)₂/2 LiH Composite

Solid–Solid Heterogeneous Catalysis: The Role of Potassium in Promoting the Dehydrogenation of the Mg(NH₂)₂/2 LiH Composite

Effect of Li₃N additive on the hydrogen storage properties of Li-Mg-N-H system