Complex Hydrides with (BH4)− and (NH2)− Anions as New Lithium Fast-Ion Conductors

Matsuo, Motoaki; Remhof, Arndt; Martelli, Pascal; Caputo, Riccarda; Ernst, Matthias; Miura, Yohei; Sato, Toyoto; Oguchi, Hiroyuki; Maekawa, Hideki; Takamura, Hitoshi; Borgschulte, Andreas; Züttel, Andreas; Orimo, Shin Ichi

doi:10.1021/ja907249p

Cited by 189 publications

(218 citation statements)

References 29 publications

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“…2 Similarly, we estimate the activation energy for self-diffusion of V − Li in LiNH 2 to be 0.71 eV, somewhat lower than the reported experimental value (0.94 eV). 49,50 As discussed in the next sections, the highly mobile Li + i and V − Li also play an important role in the decomposition of LiNH 2 and hydrogenation of Li 2 NH.…”

Section: LImentioning

confidence: 97%

Mechanisms for the decomposition and dehydrogenation of Li amide/imide

2012

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Reversible reaction involving Li amide (LiNH2) and Li imide (Li2NH) is a potential mechanism for hydrogen storage. Recent synchrotron x-ray diffraction experiments [W. I. David et al., J. Am. Chem. Soc. 129, 1594] suggest that the transformation between LiNH2 and Li2NH is a bulk reaction that occurs through non-stoichiometric processes and involves the migration of Li + and H + ions. In order to understand the atomistic mechanisms behind these processes, we carry out comprehensive first-principles studies of native point defects and defect complexes in the two compounds. We find that both LiNH2 and Li2NH are prone to Frenkel disorder on the Li sublattice. Lithium interstitials and vacancies have low formation energies and are highly mobile, and therefore play an important role in mass transport and ionic conduction. Hydrogen interstitials and vacancies, on the other hand, are responsible for forming and breaking N−H bonds, which is essential in the Li amide/imide reaction. Based on the structure, energetics, and migration of hydrogen-, lithium-, and nitrogen-related defects, we propose that LiNH2 decomposes into Li2NH and NH3 according to two competing mechanisms with different activation energies: one mechanism involves the formation of native defects in the interior of the material, the other at the surface. As a result, the prevailing mechanism and hence the effective activation energy for decomposition depend on the surface-tovolume ratio or the specific surface area, which changes with particle size during ball milling. These mechanisms also provide an explanation for the dehydrogenation of LiNH2+LiH mixtures.

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Section: LImentioning

confidence: 97%

Mechanisms for the decomposition and dehydrogenation of Li amide/imide

2012

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“…After the following re-hydrogenation, Mg(NH2)2 and LiH are regenarated and Li4BN3H10 still remains (seen in Figure 4a). The melting of Li4BN3H10 and/or Li2BNH6 may create a unique reaction environment, allowing interface reaction and mass transport of Reaction (1) to proceed at a faster rate [40]. Figure 4b shows the FTIR spectra of dehydrogenation and re-hydrogenation samples.…”

Section: The Hydrogen Desorption Properties Of 2mg(nh2)2-3lih-libh4 Cmentioning

confidence: 99%

The improved Hydrogen Storage Performances of the Multi-Component Composite: 2Mg(NH2)2–3LiH–LiBH4

Wang

Cao

et al. 2015

Energies

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2Mg(NH2)2-3LiH-LiBH4 composite exhibits an improved kinetic and thermodynamic properties in hydrogen storage in comparison with 2Mg(NH2)2-3LiH. The peak temperature of hydrogen desorption drops about 10 K and the peak width shrinks about 50 K compared with the neat 2Mg(NH2)2-3LiH. Its isothermal dehydrogenation and re-hydrogenation rates are respectively 2 times and 18 times as fast as those of 2Mg(NH2)2-3LiH. A slope desorption region with higher equilibrium pressure is observed. By means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analyses, the existence of Li2BNH6 is identified and its roles in kinetic and thermodynamic enhancement are discussed.

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“…Mixtures of metal borohydrides with halides have recently evoked careful attention as candidates for hydrogen storage materials [1][2][3][4][5][6][7] and novel solid-state lithium electrolytes [8][9][10][11]. Whereas the improvement in the hydrogen absorption and release kinetics and thermodynamics of these materials is still under investigation, their recently-discovered high ionic conductivity opens new horizons for applications.…”

Section: Introductionmentioning

confidence: 99%

Theoretical and Experimental Study of LiBH4-LiCl Solid Solution

et al. 2012

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Abstract:Anion substitution is at present one of the pathways to destabilize metal borohydrides for solid state hydrogen storage. In this work, a solid solution of LiBH 4 and LiCl is studied by density functional theory (DFT) calculations, thermodynamic modeling, X-ray diffraction, and infrared spectroscopy. It is shown that Cl substitution has minor effects on thermodynamic stability of either the orthorhombic or the hexagonal phase of LiBH 4 . The transformation into the orthorhombic phase in LiBH 4 shortly after annealing with LiCl is for the first time followed by infrared measurements. Our findings are in a good agreement with an experimental study of the LiBH 4 -LiCl solid solution structure and dynamics. This demonstrates the validity of the adopted combined theoretical (DFT calculations) and experimental (vibrational spectroscopy) approach, to investigate the solid solution formation of complex hydrides.

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Complex Hydrides with (BH₄)⁻ and (NH₂)⁻ Anions as New Lithium Fast-Ion Conductors

Cited by 189 publications

References 29 publications

Mechanisms for the decomposition and dehydrogenation of Li amide/imide

Mechanisms for the decomposition and dehydrogenation of Li amide/imide

The improved Hydrogen Storage Performances of the Multi-Component Composite: 2Mg(NH2)2–3LiH–LiBH4

Theoretical and Experimental Study of LiBH4-LiCl Solid Solution

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