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1.
《International Journal of Hydrogen Energy》2020,45(38):18782-18788
Hydrogen storage is a critical step for commercialisation of hydrogen consumed energy production. Among other storage methods, solid state storage of hydrogen attracts much attention and requires extensive research. This study rationally and systematically designs novel solid state hydrides; Li2CaH4 (GHD is obtained as −6.95 wt %) and Li2SrH4 (GHD is obtained as −3.83 wt %) using computational method. As a first step, we suggest and predict crystal structures of solid state Li2CaH4 and Li2SrH4 hydrides and look for synthesizability. Then, the mechanical stabilities of hydrides are identified using elastic constants. Both hydrides fulfil the well-known Born stability criteria, indicating that both Li2CaH4 and Li2SrH4 are mechanically stable materials. Several critical parameters, bulk modulus, shear modulus, Cauchy pressures, anisotropy factors of hydrides and bonding characteristics are obtained and evaluated. Furthermore, electronic and optical band structures of hydrides are computed. Both Li2CaH4 and Li2SrH4 have indirect bands gaps as 0.96 eV (Г-U) and 1.10 eV (Г-R). Thus, both materials are electronically semiconducting. Also, Bader charge analysis of hydrides have been carried out. Charge density distribution suggests an ionic-like (or polarized covalent) bonding interaction between the atoms. 相似文献
2.
K. Benyelloul Y. Bouhadda M. Bououdina H.I. Faraoun H. Aourag L. Seddik 《International Journal of Hydrogen Energy》2014
In this paper, the density functional theory (DFT) within the generalized gradient approximation (GGA) was used. The single crystal elastic constants for the intermetallic FeTi and its hydrides FeTiH and FeTiH2 are successfully obtained from the stress–strain relationship calculations and the strain energy-strain curves calculations, respectively. The shear modulus, Young's modulus, Poisson's ratio and shear anisotropic factors are also calculated. The bulk moduli derived from the elastic constants calculations of the cubic FeTi, orthorhombic P2221 FeTiH and Cmmm FeTiH2 are calculated. For cubic FeTi compound, the bulk modulus is in a good agreement with both theoretical results and experimental data available in the literature. More importantly, it is found that, the insertion of hydrogen into the FeTi crystal structure causes an increase in the bulk modulus. From the analysis of shear-to-bulk modulus ratio, it is found that FeTi compound and its hydrides are ductile and that this ductibility, changes with changing the concentration of hydrogen. 相似文献
3.
Various LiBH4/carbon (graphite (G), purified single-walled carbon nanotubes (SWNTs) and activated carbon (AC)) composites were prepared by mechanical milling method and further examined with respect to their hydrogen storage properties. It was found that all the carbon additives can improve the H-exchange kinetics and H-capacity of LiBH4 to some extents. Compared with G, SWNTs and AC exhibited better promoting effect on the hydrogen storage properties of LiBH4. Based on combined property/phase/structure analysis results, the promoting effect of the carbon additives was largely attributed to their heterogeneous nucleation and micro-confinement effect on the reversible dehydrogenation of LiBH4. 相似文献
4.
The effect of Ti, Co, Ni and LaCl3 on hydrogen release of NaAlH4 was studied by pressure-content-temperature (PCT) equipment. The result showed that the sample doped with 3 mol% LaCl3 presented the largest amount of hydrogen release. Increasing the amount of LaCl3 from 1 to 6 mol% caused such marked changes in behavior that the amount and rate of hydrogen release increased first and then decreased. In addition, the study on the rehydrogenation temperature of NaAlH4 doped with 3 mol% LaCl3 showed that the doped sample during the first rehydrogenation cycle carried out in PCT at 110 °C under 8 MPa after being discharged of hydrogen at 270 °C presented the largest amount of hydrogen release. 相似文献
5.
《International Journal of Hydrogen Energy》2023,48(63):24401-24411
The capability of hydrogen to be an energy source has made the hydrogen storage as one of the most investigated research fields during the recent years, and novel perovskite materials have become the current focus for hydrogen storage applications. Here we study the AeVH3 (Ae = Be, Mg, Ca, Sr) perovskite-type hydrides to explorer their potential for hydrogen storage applications using the density functional theory (DFT) implemented CASTEP code along with exchange correlation potential. The study examines the electronic structure, optical properties, elastic features and mechanical stability of the materials. The crystal structure of AeVH3 compounds is found to be cubic with lattice constant as 3.66, 3.48, 3.76 and 3.83 for Ae = Be, Mg, Ca and Sr compounds, respectively. The calculated electronic structures of these compounds show ionic bonding and no energy bandgap. The mechanical characteristics of compounds are also investigated as to meet the Born stability criterion, these compounds should be mechanically stable. The Cauchy pressure and Pugh criteria revealed that these materials have a brittle character and rather hard. In low energy range, all optical properties are found to be suitable as needed for storing the hydrogen. Furthermore, the gravimetric ratios suggested that all the compounds are suitable for hydrogen storage as a fuel for a longer time and may provide remarkable contributions in diversity of power and transportation applications. 相似文献
6.
《International Journal of Hydrogen Energy》2019,44(29):15173-15182
XNiH3 (X = Li, Na, and K) perovskite type hydrides have been studied by using Density Functional Theory (DFT) and these materials are found to be stable and synthesizable. The X-ray diffraction patterns have been obtained and they indicate that all materials have the polycrystalline structure. The electronic properties have been investigated and it has been found that these structures show metallic character. The Bader partial charge analysis has also been performed. In addition, the elastic constants have been calculated and these materials are found to be mechanically stable. Using these elastic constants, the mechanical properties such as bulk modulus, shear modulus, Poisson's ratio have been obtained. Moreover, the Debye temperatures and thermal conductivities have been studied. The anisotropic elastic properties have been visualized in three dimensions (3D) for Young's modulus, linear compressibility, shear modulus and Poisson's ratio as well as with the calculation of the anisotropic factors. Additionally, the dynamical stability has been investigated and obtained phonon dispersion curves show that these materials are dynamically stable. Also, the thermal properties including free energy, enthalpy, entropy and heat capacity have been studied. The hydrogen storage properties have been examined and the gravimetric hydrogen storage capacities have been calculated as 4.40 wt%, 3.57 wt% and 3.30 wt% for LiNiH3, NaNiH3 and KNiH3, respectively. Furthermore, the hydrogen desorption temperatures have been obtained as 446.3 K, 419.5 K and 367.5 K for LiNiH3, NaNiH3 and KNiH3, respectively. 相似文献
7.
Jing-Hua Guo Dan-Dan Liu Xiao-Dong Li Hai-Ying Liu Gang Chen 《International Journal of Hydrogen Energy》2018,43(4):2247-2255
Penta-graphene is a new 2D allotrope of carbon exclusively consists of pentagons in a planar sheet geometry. In this work, we explored that if it can be a substrate for hydrogen spillover. The density-functional theory (DFT) studies show that the H atom can stably adsorb on sp2 carbons. The saturation hydrogen storage density of penta-graphene is estimated to be 5.3 wt%. The Pt4, Pd4 Ni4, and Ti4 clusters are used as the catalyst for hydrogen spillover, and the migration barriers are 1.25, 1.07, 1.03 and 1.35 eV, respectively. The kinetic Monte Carlo simulations are performed to study the migration process for massive H atoms. The results show that the optimal reaction temperatures are 467, 405, 390, and 504 K for Pt4, Pd4, Ni4, and Ti4 catalyst, respectively. For Pd4 and Ni4 catalysts, the spillover reaction can occur at the appropriate temperature (355 and 340 K, respectively) for onboard hydrogen storage systems applied to light-duty vehicles. 相似文献
8.
To improve the hydrogen storage property of LiBH4, the LiBH4/Ca(AlH4)2 reactive systems with various ratios were constructed, and their de-/hydrogenation properties as well as the reaction mechanisms were investigated experimentally. It was found that the sample with the LiBH4 to Ca(AlH4)2 molar ratio of 6:1 exhibits the best comprehensive hydrogen storage properties, desorbing hydrogen completely (8.2 wt.%) within 35 min at 450 °C and reversibly absorbing 4.5 wt.% of hydrogen at 450 °C under a hydrogen pressure as low as 4.0 MPa. During the first dehydrogenation process of the LiBH4/Ca(AlH4)2 systems, the CaH2 and Al particles were in situ precipitated via the self-decomposition of Ca(AlH4)2, and then reacted with LiBH4 to form CaB6, AlB2 and LiH. Whereafter, the sample can cycle between LiBH4 + Ca(BH4)2 + Al in the hydrogenated state and CaB6 + AlB2 + LiH in the dehydrogenated state. 相似文献
9.
Complex ternary hydrides based in Mg and transition metals are very attractive materials for hydrogen and energy storage due to their large volumetric capacity, up to 150 kgH2/m3 in Mg2FeH6 and their high dissociation enthalpies. These compounds may be produced at room temperature by mechanical milling of the constituents in H2 atmosphere. This technique has also served to explore the synthesis of quaternary hydrides Mg2T1−zT’zHy, combining two transition metals to optimize the properties of the resulting hydride. In the present work we analyze the mechanical synthesis of the compounds Mg2Fe1−zCozHy (z = 0, ¼, ½, ¾, 1) by mechanical alloying at room temperature Mg-Fe-Co powder mixtures in adequate proportion, at 0.3 MPa H2. We follow the mechanosynthesis process trough the analysis of the hydrogen absorption kinetic curves. Samples obtained after a steady state was reached were characterized by X ray diffraction and Mössbauer spectroscopy. The different stages in the mechanosynthesis of these complex hydrides are discussed in terms of the composition and initial state of the powder mixture. 相似文献
10.
Bilal Rehmat M.A. Rafiq Y. Javed Z. Irshad Nisar Ahmed S.M. Mirza 《International Journal of Hydrogen Energy》2017,42(15):10038-10046
Density functional theory (DFT) was used to study mechanical properties of orthorhombic and cubic LiBeH3 and cubic NaBeH3. The band gaps were estimated using different approximations available in the WIEN2k code. The elastic constants of LiBeH3 and NaBeH3 were calculated. Both hydrides were found to be stable mechanically. From elastic constants, the bulk modulus and the linear bulk modulus along crystallographic axes of single crystal were calculated. The calculated values of linear bulk moduli were in good agreement with the reported theoretical values. Young's and Shear moduli, Poisson's ratio and micro-hardness for ideal polycrystalline LiBeH3 and NaBeH3 were also calculated. Both these hydrides can be classified as brittle materials according to obtained results. The values of bulk, shear and Young's moduli obtained in our study were higher than those reported for other popular hydrides for hydrogen storage. Shear and elastic anisotropic factors along with Debye temperature are also discussed using theoretical elastic constants. 相似文献
11.
B.A. Talagañis M.R. Esquivel G. Meyer 《International Journal of Hydrogen Energy》2011,36(18):11961-11968
LaNi5 was obtained from raw materials by low energy mechanical alloying. Hydriding properties of as-milled intermetallic were improved by annealing. Pressure-composition isotherms showed flat plateaus when annealing temperature was 600 °C, this value is at least 300 °C lower than the synthesis and annealing temperature of standard equilibrium methods. This low energy mechanical alloying - low temperature annealing procedure reduces the number of intermediate stages needed to scale up the fabrication of the intermetallic. After cycling this material in hydrogen, its hydriding properties were studied in the 25-90 °C range. From these results, we propose a one-stage hydrogen thermal compression scheme working between 25 °C (absorption) and 90 °C (desorption) with a compression ratio of 2.5 and a useful capacity of 1.0 mass %. 相似文献
12.
S.X. Zhao C.Y. Wang D.M. Liu Q.J. Tan Y.T. Li T.Z. Si 《International Journal of Hydrogen Energy》2018,43(10):5098-5103
The de-/rehydrogenation features of the 6LiBH4/SrF2 reactive hydride system have been systematically investigated. It was found that the thermal stability of LiBH4 can be reduced markedly by combining it with SrF2. Dehydrogenation of the 6LiBH4/SrF2 system proceeds via the 6LiBH4 + SrF2 → SrB6 + 2LiF + 4LiH + 10H2 reaction, which involves SrH2 as the intermediate product. The dehydrogenation enthalpy change was experimentally determined to be 52 kJ/mol H2 based on the P–C isotherm analysis. For rehydrogenation, LiBH4 and SrF2 were regenerated along with LiSrH3 at 450 °C under ~8 MPa hydrogen pressure; thus, approximately 5.2 wt% of hydrogen can be released during the second dehydrogenation process. 相似文献
13.
Lathapriya Vellingiri Karthigeyan Annamalai Ramamurthi Kandasamy Iyakutti Kombiah 《International Journal of Hydrogen Energy》2018,43(22):10396-10409
Structural, spectral, morphological, thermal and hydrogen storage properties of the multi-walled carbon nanotubes functionalized with SnO2 particles (MWCNT/SnO2) heat treated at 300, 350 and 400 °C in air were systematically investigated. X-ray diffraction from (110), (101) and (211) planes of SnO2, (002) plane of MWCNT and shift towards higher angle confirmed the formation of composites. XPS, Raman, FTIR and TGA analyses revealed that C–O bond on the surface of MWCNT acts as the nucleation sites for SnO2 which resulted in a strong interaction between MWCNT and SnO2. Presence of C, Sn and O was confirmed by EDX and XPS analyses. Hydrogen adsorption was carried out using hydrogenation set-up and H2 adsorption/desorption behavior of the composites were studied employing Raman and thermogravimetric analyses. Size, morphology and interaction between MWCNT and SnO2 were impacted significantly by the heat treatment which resulted in high hydrogen storage capacity of 2.13 and 2.62 wt % for 15 and 30 min hydrogenation time for the nanocomposite heat treated at 400 °C. 相似文献
14.
Somwan Chumphongphan Mark Paskevicius Drew A. SheppardCraig E. Buckley 《International Journal of Hydrogen Energy》2013
A simple mechanical milling and annealing process has been used to synthesize CaNi5-based hydrogen storage alloys. Heat treatment at 800 °C under vacuum results in the formation of a crystalline CaNi5 phase. Secondary phases, including Ca2Ni7 and Mo–Ni, are formed when substituting Mo for Ni. Replacement of Ni by Al or Mo leads to an increase in the unit cell volume of the CaNi5 phase. The hydrogen storage capacity of all substituted alloys is reduced and the plateau pressures are lower than those of pure CaNi5. Fairly flat plateau regions are retained for all compositions except the CaNi4.8Mo0.2 composition where a Ca2Ni7 phase is dominant. The incorporation of Mo also causes slow sorption kinetics for the CaNi4.9Mo0.1 alloy. CaNi4.9Al0.1 maintains its initial hydrogen absorption capacity for 20 cycles performed at 85 °C but the other substituted alloys lose their capacity rapidly, especially the CaNi4.8Mo0.2 composition. 相似文献
15.
Guang-lin Xia Hai-yan LengNai-xin Xu Zhi-lin LiZhu Wu Jun-lin Du Xue-bin Yu 《International Journal of Hydrogen Energy》2011,36(12):7128-7135
Though LiBH4-MgH2 system exhibits an excellent hydrogen storage property, it still presents high decomposition temperature over 350 °C and sluggish hydrogen absorption/desorption kinetics. In order to improve the hydrogen storage properties, the influence of MoCl3 as an additive on the hydrogenation and dehydrogenation properties of LiBH4-MgH2 system is investigated. The reversible hydrogen storage performance is significantly improved, which leads to a capacity of about 7 wt.% hydrogen at 300 °C. XRD analysis reveals that the metallic Mo is formed by the reaction between LiBH4 and MoCl3, which is highly dispersed in the sample and results in improved dehydrogenation and hydrogenation performance of LiBH4-MgH2 system. From Kissinger plot, the activation energy for hydrogen desorption of LiBH4-MgH2 system with additive MoCl3 is estimated to be ∼43 kJ mol−1 H2, 10 kJ mol−1 lower than that for the pure LiBH4-MgH2 system indicating that the kinetics of LiBH4-MgH2 composite is significantly improved by the introduction of Mo. 相似文献
16.
N.A. Sazelee N.H. Idris M.F. Md Din N.S. Mustafa N.A. Ali M.S. Yahya F.A. Halim Yap N.N. Sulaiman M. Ismail 《International Journal of Hydrogen Energy》2018,43(45):20853-20860
Previous studies have shown that ferrites give a positive effect in improving the hydrogen sorption properties of magnesium hydride (MgH2). In this study, another ferrite, i.e., BaFe12O19, has been successfully synthesised via the solid state method, and it was milled with MgH2 to enhance the sorption kinetics. The result showed that the MgH2 + 10 wt% BaFe12O19 sample started to release hydrogen at about 270 °C which is about 70 °C lower than the as-milled MgH2. The doped sample was able to absorb hydrogen for 4.3 wt% in 10 min at 150 °C, while as-milled MgH2 only absorbed 3.5 wt% of hydrogen under similar conditions. The desorption kinetic results showed that the doped sample released about 3.5 wt% of hydrogen in 15 min at 320 °C, while the as-milled MgH2 only released about 1.5 wt% of hydrogen. From the Kissinger plot, the apparent activation energy of the BaFe12O19-doped MgH2 sample was 115 kJ/mol which was lower than the milled MgH2 (141 kJ/mol). Further analyses demonstrated that MgO, Fe and Ba or Ba-containing contribute to the improvement by serving as active species, thus enhancing the MgH2 for hydrogen storage. 相似文献
17.
The hydrogen storage phase of an energy storage plant based on metallic hydrides has a strong influence on the total efficiency of storage power plants as well as on their response time. The technique presented in this paper uses a hydrogen-metal chemical bond during its storage. This paper describes a metal hydride cylinder modeled and simulated by using the main quantities involved in the adsorption and desorption processes as well as in an analysis of the influence of thermal quantities involved in these processes. As a result, a proposal for automation of the thermal exchange of the modeled cylinder is presented and the possibilities of evaluation of this technique. 相似文献
18.
M.S. Yahya N.N. Sulaiman N.S. Mustafa F.A. Halim Yap M. Ismail 《International Journal of Hydrogen Energy》2018,43(31):14532-14540
The catalytic effects of K2NbF7 on the hydrogen storage properties of MgH2 have been studied for the first time. MgH2 + 5 wt% K2NbF7 has reduced the onset dehydrogenation temperature to 255 °C, which is 75 °C lower than the as-milled MgH2. For the rehydrogenation kinetic, at 150 °C, MgH2 + 5 wt% K2NbF7 absorbs 4.7 wt% of hydrogen in 30 min whereas the as-milled MgH2 only absorbs 0.7 wt% of hydrogen under similar condition. For the dehydrogenation kinetic, at 320 °C, the MgH2 + 5 wt% K2NbF7 is able to release 5.2 wt% of hydrogen in 5.6 min as compared to 0.3 wt% by the as-milled MgH2 under similar condition. Comparatively, the Ea value of MgH2 + 5 wt% K2NbF7 is 96.3 kJ/mol, which is 39 kJ/mol lower compared to the as-milled MgH2. The MgF2, the KH and the Nb that are found after the heating process are believed to be the active species that have improved the system properties. It is concluded that the K2NbF7 is a good catalyst to improve the hydrogen storage properties of MgH2. 相似文献
19.
Chuan Liu Shengli Zhang Peng Wang Shiping Huang Huiping Tian 《International Journal of Hydrogen Energy》2013
Confinement effect on the structural, electronic and thermodynamic properties of LiBH4 is investigated by density functional theory. The thermodynamically and dynamically stable confinement structure is testified to be γ-LiBH4@C31Ti according to the adsorption energy and vibrational frequency calculations. The tridentate structure formed by [BH4]− and Li+ in the unconfined LiBH4 changes into bidentate structure in γ-LiBH4@C31Ti. We observe that both the occupied and unoccupied states of H 1s, B 2s, B 2p, Li 2s, and Li 2p orbitals in the partial DOSs of γ-LiBH4@C31Ti shift to high energy level and the splits of DOS peaks occur at the states of H 1s, B 2p, and Li 2p orbitals. Different from the first-step decomposition reaction of LiBH4, the one for γ-LiBH4@C31Ti changes into 2LiBH4@C31Ti → 2LiH + 2B@C31Ti + 3H2. Moreover, the reaction enthalpy for the first-step decomposition reaction of γ-LiBH4@C31Ti decreases to 5.864 eV, which is smaller than that (17.204 eV) of LiBH4. According to the hydrogen removal energy calculations, we observe that the confinement effects make the removal of the first and second hydrogen atoms in γ-LiBH4@C31Ti easy. 相似文献
20.
Jianjun Jiang Jia WeiHaiyan Leng Qian LiKuo-Chih Chou 《International Journal of Hydrogen Energy》2013
The various Mg–B–Al–H systems composed of Mg(BH4)2 and different Al-sources (metallic Al, LiAlH4 and its decomposition products) have been investigated as potential hydrogen storage materials. The role of Al was studied on the dehydrogenation and the rehydrogenation of the systems. The results indicate that the different Al-sources exhibit a similar improving effect on the dehydrogenation properties of Mg(BH4)2. Taking the Mg(BH4)2 + LiAlH4 system as an example, at first LiAlH4 rapidly decomposes into LiH and Al, then Mg(BH4)2 decomposes into MgH2 and B, finally the MgH2 reacts with Al, LiH and B, which forms Mg3Al2 and MgAlB4. The system starts to desorb H2 at 140 °C and desorbs 3.6 wt.% H2 below 300 °C, while individual Mg(BH4)2 starts to desorb H2 at 250 °C and desorbs only 1.3 wt.% H2 below 300 °C. The isothermal desorption kinetics of the Mg–B–Al–H systems is about 40% faster than that of Mg(BH4)2 at the hydrogen desorption ratio of 90%. In addition, the Mg–B–Al–H systems show partial reversibility at moderate temperature and pressure. For Al-added system, the product of rehydrogenation is MgH2, while for LiAlH4-added system the product is composed of LiBH4 and MgH2. 相似文献