Onset Dehydrogenation Temperature Research Articles

Improved hydrogen storage properties of MgH2 by the addition of TiCN and its catalytic mechanism

The hydrogen storage properties of MgH2–x wt%TiCN (x = 5, 10, 15) composites were systematically investigated and the results show that the addition of TiCN can effectively improve the de/rehydrogenation kinetics of MgH2. Taken the onset dehydrogenation temperature and isothermal de/rehydrogenation kinetics into consideration, the MgH2–10 wt% TiCN composite was shown to have the best performance. It was found that the MgH2–10 wt% TiCN composite could release 4 wt% H2 in 17.3 min at 300 °C while the as-synthesized MgH2 could not release any hydrogen under the same condition. Besides, the MgH2–10 wt% TiCN composite could absorb 4.63 wt% H2 under 3.2 MPa hydrogen pressure at 300 °C within 20 s. Compared with as-synthesized MgH2, the activation energy of the MgH2–10 wt% TiCN composite was significantly decreased from 183.76 ± 10 to 106.82 ± 5 kJ/mol. X-ray diffraction analysis revealed that the TiCN remained stable during the ball milling and the following de/rehydrogenation cycle. The catalytic mechanism was also proposed that the TiCN particles absorbed on MgH2 not only served as charge transfer centers and accelerated the hydrogen incorporation and dissociation rate but also provided more diffusion channels for hydrogen, which contributed to the good de/rehydrogenation properties of MgH2.

Discrepancy in the thermal decomposition/dehydrogenation of ammonia borane screened by thermogravimetric analysis

Ammonia borane NH3BH3 (AB), in pristine or destabilized state, has been much investigated as a solid-state chemical hydrogen storage material. The potential of such compound for thermolytic dehydrogenation (and decomposition) can be fast and reliably screened and assessed by thermogravimetric (TG) analysis via descriptors like both the onset temperature of dehydrogenation and the overall weight loss over the temperature range 100–200 °C. However, comparisons to results reported in the open literature need to be done with caution. The objective of the present article is thus to show that the thermolytic properties of AB determined by TG analysis are much dependent on the operation conditions. We have observed that much different results are obtained by changing the analyzer, and especially the crucible (comparable to a semi-closed reactor in one case or similar to an open reactor in the second case). For example, a stable AB sample is able to suffer a weight loss of 18.4 wt% starting from 116.5 °C when a semi-closed crucible is used, versus a weight loss of 51.9 wt% starting from 91 °C with the utilization of an open crucible. Our main results are reported herein in the form of a short technical communication: it aims at sharing our experimental observations in order to avoid misinterpretation and misunderstanding as for the TG analyses of AB and of any kind of derivatives. The present work should help in comparing the data available in the open literature with care and, from now on, should be regarded as a key study to report comparable TG results for AB thermolytic dehydrogenation.

Synergistic effects of transition metal halides and activated carbon nanofibers on kinetics and reversibility of MgH2

MgH2 doped with transition metal halides (TiF4, NbF5, and ZrCl4) and activated carbon nanofibers (ACNF) for reversible hydrogen storage is prepared by ball milling technique. Transition metal halides provide catalytic effects for de/rehydrogenation kinetics, while ACNF benefits thermal conductivity and hydrogen permeability as well as prevents particle agglomeration during cycling. Significant reduction of onset and main dehydrogenation temperatures of MgH2 (ΔT = 243 and 158 °C, respectively) are achieved by doping with 5–10 wt % of NbF5, ACNF-TiF4 and ACNF-NbF5. During the 1st cycle, the latter samples liberate 4.7–5.0 wt % H2 within 1 h 30 min, whereas MgH2 doped with ACNF reaches only 1.5 wt % H2. The reaction between MgF2 and NbHx (x < 1) (MgH2-NbF5 and MgH2-ACNF-NbF5) during dehydrogenation results in the formation of new catalytic active species of Nb-F-Mg favoring kinetics. Upon four hydrogen release and uptake cycles, kinetics and reversibility within 1 h 30 min of MgH2-ACNF-NbF5 are preserved at 5.0 wt % H2, while those of MgH2-NbF5 and MgH2-ACNF-TiF4 decay to 4.4 wt % H2. Activation energy (EA) for dehydrogenation of MgH2 considerably decreases from 140.0 ± 10.2 to 37.8 ± 1.5 kJ/mol after doing with ACNF-NbF5. Superior performance of MgH2-ACNF-NbF5 to MgH2-NbF5 is due to synergistic effects of NbF5 and ACNF. In the case of MH2-ACNF-TiF4, the disappearance of active species benefiting kinetic properties and the formation of thermally stable TiH2 account for inferior hydrogen content reversible.

Hydrogen storage performances and reaction mechanism of non-stoichiometric compound Li1.3Na1.7AlH6 doped with Ti3C2

Our previous work found that Li1.3Na1.7AlH6 possesses the lowest dehydrogenation onset temperature and the most favorable dehydrogenation thermal stability among Li-Na-Al-H compounds (Fan et al., 2017). In this work, additional Ti3C2 was introduced into Li1.3Na1.7AlH6 by ball milling to further enhance its dehydrogenation performances. According to the volumetric release curves, the initial dehydrogenation temperature of the sample Li1.3Na1.7AlH6 + 5 wt.%Ti3C2 was lowered by 35 K from that of the pristine Li1.3Na1.7AlH6. The dehydrogenation enthalpy values of Li1.3Na1.7AlH6 + 5 wt.%Ti3C2 (46.9 KJ mol H2−1) was also slightly lower than that of pristine Li1.3Na1.7AlH6 (49.7 KJ mol H2−1). It means that the doped Ti3C2 was actively involved in the reaction with Li1.3Na1.7AlH6 during the dehydrogenation process. The investigation by X-ray photoelectron spectroscopy (XPS) demonstrated that the reaction between Ti element and Li1.3Na1.7AlH6 was definitely carried out in which the zero valence of Ti was transformed into Ti3+.

Improvement of hydrogen storage properties in MgH2 catalysed by K2NbF7

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.

Improved hydrogen storage properties of LiBH4 confined with activated charcoal by ball milling

In order to enhance the hydrogen storage properties of LiBH4, activated charcoal (AC) was used as the scaffold to confine LiBH4 in this paper. Ball milling was used to prepare LiBH4/AC composites. Experimental results show that dehydrogenation properties of ball-milled LiBH4/AC (LiBH4/AC-BM) are greatly improved compared with that of pristine LiBH4, ball-milled LiBH4 (LiBH4-BM) and hand-milled LiBH4/AC (LiBH4/AC-HM). The onset dehydrogenation temperature of LiBH4 for LiBH4/AC-BM is around 160 °C, which is 170 °C lower than that of pristine LiBH4. At around 400 °C, LiBH4/AC-BM finishes the dehydrogenation with a hydrogen capacity of 13.6 wt%, which is approximately the theoretical dehydrogenation capacity of pure LiBH4 (13.8 wt%), while the dehydrogenation processes for LiBH4-BM and LiBH4/AC-BM do not finish even when they were heated to 600 °C. The isothermal dehydriding measurements show that it takes only 15 min for LiBH4/AC-BM to reach a dehydrogenation capacity of 10.1 wt% at 350 °C, whereas the pristine LiBH4 and the LiBH4/AC-HM release hydrogen less than 1 wt% under the same conditions. The dehydrogenation process and the effect of AC were discussed.

Reversible hydrogen sorption and kinetics of hydrogen storage tank based on MgH2 modified by TiF4 and activated carbon

By doping with 5 wt % TiF4 and activated carbon (AC), onset and main dehydrogenation temperatures of MgH2 significantly reduce (ΔT = 138 and 109 °C, respectively) with hydrogen capacity of 4.4 wt % H2. Up-scaling to storage tank begins with packing volume and sample weight of 28.8 mL and ∼14.5 g, respectively, and continues to 92.6 mL and ∼60.5–67 g, respectively. Detailed hydrogen sorption mechanisms and kinetics of the tank tightly packed with four beds of MgH2TiF4-AC (∼60.5 g) are investigated. De/rehydrogenation mechanisms are detected by three temperature sensors located at different positions along the tank radius, while hydrogen permeability is benefited by stainless steel mesh sheets and tube inserted in the hydride beds. Fast desorption kinetics of MgH2TiF4-AC tank at ∼275–283 °C, approaching to onset dehydrogenation temperature of the powder sample (272 °C) suggests comparable performances of laboratory and tank scales. Hydrogen desorption (T = 300 °C and P(H2) = 1 bar) and absorption (T = 250 °C and P(H2) = 10–15 bar) of MgH2TiF4-AC tank provide gravimetric and volumetric capacities during the 1st-2nd cycles of 4.46 wt % H2 and 28 gH2/L, respectively, while those during the 3rd-15th cycles are up to 3.62 wt % H2 and 23 gH2/L, respectively. Due to homogeneous heat transfer along the tank radius, de/rehydrogenation kinetics superior at the tank center and degrading forward the tank wall can be due to poor hydrogen permeability. Particle sintering and/or agglomeration upon cycling yield deficient hydrogen content reproduced.

A novel solid-solution MXene (Ti0.5V0.5)3C2 with high catalytic activity for hydrogen storage in MgH2

A novel solid-solution MXene (Ti0.5V0.5)3C2 is successfully synthesized by exfoliating a solid-solution MAX phase (Ti0.5V0.5)3AlC2, and its catalytic effect on the hydrogen storage reaction of Mg is systemically evaluated for the first time. Typical layer morphology is observed for the prepared (Ti0.5V0.5)3C2, which exhibits a better catalytic activity than that of Ti3C2. The addition of 10 wt% (Ti0.5V0.5)3C2 remarkably reduces the dehydrogenation onset temperature of MgH2 by 70 °C, from 266 to 196 °C. At 250 °C, approximately 5.0 wt% H2 is released from the 10 wt% (Ti0.5V0.5)3C2-containing MgH2 within 20 min. The dehydrogenated sample rapidly absorbs 4.8 wt% H2 within 5 s at 120 °C; these hydrogenation kinetics are much more superior even to the well-studied Nb2O5 catalyst. The apparent activation energy is calculated to be 77.3 kJ/mol for the MgH2-10 wt% (Ti0.5V0.5)3C2 sample, which is only around half of that of the pristine MgH2 (153.8 kJ/mol). This is responsible for the remarkably reduced dehydrogenation operating temperature. Moreover, the chemical states of (Ti0.5V0.5)3C2 during dehydrogenation are also analysed and discussed.

Enhancing hydrogen storage performances of MgH2 by Ni nano-particles over mesoporous carbon CMK-3

Nano-dispersed Ni particles over mesoporous carbon material CMK-3 (Ni/CMK-3) was fabricated by means of impregnation-reduction strategy using precursor NiCl2 · 6H2O, which is beneficial to improving the de/rehydrogenation performances of MgH2. The dehydrogenation onset temperature of MgH2–Ni/CMK-3 is significantly lowered by 170 K from that of pristine MgH2 (around 603 K). Totally 5.9 wt% of hydrogen absorption capacity is liberated within 1 h at a temperature of 423 K under a pressure of 3 MPa. This composite can absorb 3.9 wt% hydrogen even at a temperature of 328 K under 3 MPa H2. Activation energy values of both dehydrogenation (43.4 kJ mol−1) and rehydrogenation (37.4 kJ mol−1) for MgH2–Ni/CMK-3 are greatly enhanced from those of as-milled MgH2. Ni/CMK-3 also slightly destabilizes the dehydrogenation of MgH2 by 1.5 kJ mol The enhanced performances can be attributed to the synergistic effects of both destabilization and activation from nano-dispersed Ni particles.

Synthesis of Mg-based composite material with in-situ formed LaH3 and its hydrogen storage characteristics

In this work, a Mg-based composite material with in-situ formed LaH3, Mg2NiH4-LiBH4 + 20 wt% LaH3, was prepared by ball milling LiBH4 and hydrogenated LaMg2Ni and Mg2Ni powder mixture, followed by heat treatment at 573 K. The onset dehydrogenation temperature of the composite is reduced by 50 K compared with that of Mg2NiH4-LiBH4. The LaH3-doped composite shows faster kinetics, absorbing 1.43 wt% hydrogen within 100 s at 423 K, which is 6.5 times faster than Mg2NiH4-LiBH4. Moreover, the composite releases 1.24 wt% hydrogen within 500 s at 573 K, 0.69 wt% higher than Mg2NiH4-LiBH4. The activation energy of the composite is reduced by 8.2 and 80 kJ/mol compared with that of Mg2NiH4-LiBH4 and commercial MgH2, respectively. The improvement in hydrogen storage properties is attributed to the fact that LaH3 promotes the generation of nano-sized spongy Mg structure, which has good catalytic activity during the subsequent hydrogenation/dehydrogenation process.

Facile Synthesis and Superior Catalytic Activity of Nano-TiN@N-C for Hydrogen Storage in NaAlH4.

Herein, we synthesize successfully ultrafine TiN nanoparticles (<3 nm in size) embedded in N-doped carbon nanorods (nano-TiN@N-C) by a facile one-step calcination process. The prepared nano-TiN@N-C exhibits superior catalytic activity for hydrogen storage in NaAlH4. Adding 7 wt % nano-TiN@N-C induces more than 100 °C reduction in the onset dehydrogenation temperature of NaAlH4. Approximately 4.9 wt % H2 is rapidly released from the 7 wt % nano-TiN@N-C-containing NaAlH4 at 140 °C within 60 min, and the dehydrogenation product is completely hydrogenated at 100 °C within 15 min under 100 bar of hydrogen, exhibiting significantly improved desorption/absorption kinetics. No capacity loss is observed for the nano-TiN@N-C-containing sample within 25 de-/hydrogenation cycles because nano-TiN functions as an active catalyst instead of a precursor. A severe structural distortion with extended bond lengths and reduced bond strengths for Al-H bonding when the [AlH4]- group adsorbs on the TiN cluster is demonstrated for the first time by density functional theory calculations, which well-explains the reduced de-/hydrogenation temperatures of the nano-TiN@N-C-containing NaAlH4. These findings provide new insights into designing and synthesizing high-performance catalysts for hydrogen storage in complex hydrides.

Improved Dehydrogenation Performance of Li-B-N-H by Doped NiO

In order to improve the dehydrogenation properties of the Li-B-N-H system, a flower-like NiO was successfully synthesized using the hydrothermal method. The effect of the NiO on the dehydrogenation properties of the LiBH4-2LiNH2 system was studied. The results showed that the dehydrogenation properties of the LiBH4-2LiMH2 system were significantly enhanced by doping with NiO. The composite doped with 5 wt. % NiO exhibited optimal hydrogen storage properties. It released about 10.5 wt. % hydrogen below 300 °C, and the onset dehydrogenation temperature was only 90 °C, 110 °C lower than that of LiBH4-2LiNH2. The isothermal dehydrogenation experiment indicated that the LiBH4-2LiNH2-5 wt. % NiO composite released 8.8 wt. % hydrogen within 15 min at 150 °C. Structural analysis revealed that the as-prepared NiO was reduced to metallic Ni, which worked as an active catalytic species in the remainder of the dehydrogenation process. The Mass Spectrometer (MS) analyses showed that the doped NiO inhibited the content of NH3 released in the process of the dehydrogenation of LiBH4-2LiNH2-NiO.

Effects of TiF3 addition on the hydrogen storage properties of 4MgH2 + Cd composite

In this paper, the best performance of the MgH2 destabilized system with different ratios of Cd (1:1, 2:1, 3:1 and 4:1) have been studied for the first time. Remarkable enhancements on the onset dehydrogenation temperature, as well as the isothermal de/rehydrogenation kinetics were shown by the 4MgH2 + Cd composite. In order to improve the hydrogen storage properties of the 4MgH2 + Cd, TiF3 was added and its catalytic effects were investigated. Temperature programmed dehydrogenation result had revealed that the onset dehydrogenation temperature was improved once the 10 wt% TiF3 was incorporated into the 4MgH2 + Cd system. The absorption and desorption kinetics were also improved compared to the un-doped 4MgH2 + Cd composite system. The scanning electron microscope result had displayed that the 4MgH2 + Cd + 10 wt% TiF3 had the smallest particle size compared to the pure and the ball-milled MgH2, as well as the 4MgH2 + Cd composite system. The X-ray diffraction results had demonstrated the formation of an intermediate compound, Mg3Cd, which was formed during the heating process. For the TiF3-doped sample, it is reasonable to conclude that the in-situ formed TiH2 and F-containing species play a synergetic role to encourage interactions between the MgH2 and the Cd and thus further ameliorate the performances of the hydrogen storage of 4MgH2 + Cd composite system.

Role of Metal Electronegativity in the Dehydrogenation Thermodynamics and Kinetics of Composite Metal Borohydride-LiNH2 Hydrogen Storage Materials.

The composites of M(BH4) n-LiNH2 (1/2 n molar ratio, n = 1 or 2, M = Ca, Mg, Li) were synthesized by liquid ball milling. Samples were characterized by X-ray diffraction, thermogravimetry-differential thermal analysis-mass spectroscopy (TG-DTA-MS), and kinetic models (Achar differential/Coats-Redfern integral method). The higher-electronegativity metal M in M(BH4) n-4LiNH2 (M = Ca, Mg) samples not only enables [BH4]- group to release easily, so as to facilitate the interaction of [BH4]- and [NH2]- groups, but also restrains the NH3 release and slightly decreases the onset dehydrogenation temperature concluded by TG-MS. Moreover, in stage 1 (200-350 °C), the kinetics performances of M(BH4) n-4LiNH2 (M = Ca, Mg) samples are distinctly improved, that is, the activation energies of them are reduced by ca. 30% compared to those of sample LiBH4-2LiNH2. The outstanding contribution of the replacement of M(BH4) n with high-electronegativity metal ion is to both improve the kinetics performance by changing the kinetics mechanism and decrease the temperature range of the initial dehydrogenation region.

Graphene‐Tailored Thermodynamics and Kinetics to Fabricate Metal Borohydride Nanoparticles with High Purity and Enhanced Reversibility

AbstractDue to their ultrahigh theoretical capacity, metal borohydrides are considered to be one of the most promising candidate hydrogen storage materials. Their application still suffers, however, from high operating temperature, sluggish kinetics, and poor reversibility. Designing nanostructures is an effective way of addressing these issues, but seeking suitable approaches remains a big challenge. Here, a space‐confined solid‐gas reaction to synthesize Mg(BH4)2 nanoparticles supported on grapheme is reported, which serves as the structural support for the dispersed Mg(BH4)2 nanoparticles. More notably, density functional theory calculations reveal that graphene could weaken both the MgH bonds of MgH2 and BB bonds of B2H6, which could thermodynamically and kinetically facilitate the chemical transformation to synthesize Mg(BH4)2 with high purity. Because of the synergistic effects of both the significant reduction in particle size and the catalytic effect of graphene, an onset dehydrogenation temperature of ≈154 °C is observed for Mg(BH4)2 nanoparticles, and a complete dehydrogenation could be achieved at a temperature as low as 225 °C, with the formation of MgB2 as the by‐product. This work provides a new perspective to tailoring the thermodynamics and kinetics of chemical reactions toward the favorable synthesis of functional inorganic materials.

Improvement in hydrogen storage properties of MgH2 catalyzed with BaTiO3 additive

The MgH2+20 wt. % BaTiO3 composites is prepared by ball milling MgH2 with 20 wt. % BaTiO3, and the effect of BaTiO3 on the hydrogen storage properties of the MgH2 is investigated. TPD (Temperature-programmed-desorption) results showed that with addition of BaTiO3, the onset dehydrogenation temperature of the composite is 270 °C, which is 149 ºC lower than that of pure MgH2. And the hydrogen absorption / desorption rates of MgH2 + 20 wt.% BaTiO3 are 2.21 times and 2.12 times of pure MgH2 at certain temperatures and hydrogen pressures, respectively. Furthermore, BaTiO3 additives decreased the dehydriding activation energy of MgH2 from 116 kJ/mol to 108 kJ/mol. BaTiO3 plays an effective catalyst role in the hydrogenation / dehydrogenation process of MgH2.

Catalytic effect of graphene on the hydrogen storage properties of Mg-Li alloy

The Mg-Li-xgraphene(Gp) (x = 0,1,3,5) composites were synthesized by sintering and ball-milling, and the catalytic effect of the graphene on the hydrogen storage properties of the Mg-Li-xGp(x = 0,1,3,5) composites was investigated. Experimental results indicated that the addition of the graphene enhanced the reversible hydrogenation reaction of the Mg-Li alloy and reduced significantly the onset hydrogenation/dehydrogenation temperature of the Mg-Li alloy. For example, the reversible hydrogenation reaction occurred in the case of the Mg-Li-xGp(x = 3,5) composites at 300 °C, while it did not occur in the case of the Mg-Li alloy at the same temperature. The onset temperature of dehydrogenation for Mg-Li alloy was about 338 °C, by comparison, and the onset temperature of dehydrogenation for Mg-Li-xGp(x = 3,5) composites decreased to 276 °C. In addition, the Mg-Li-xGp(x = 1,3,5) composites could release more than 90% of the hydrogen absorbed when heated at a rate of 2 °C/min from room temperature to 353 °C, while only 39% of the hydrogen absorbed in the Mg-Li alloy was released in the same condition, which is resulted from the decrease of the apparent activation energy (Ea) of dehydrogenation for the Mg-Li alloy with the graphene addition. Graphene acts as a catalyst, thereby lowering the reaction barrier for dehydrogenation of the Mg-Li alloy, which in turn promotes the reversible hydrogenation/dehydrogenation reaction of the alloy.

Enhanced thermal diffusivity and dehydrogenation of 2LiNH2[sbnd]MgH2 by doping with super activated carbon

Doping with the additives in metal-N–H system has been regarded as one of the most effective approaches to improve its hydrogen storage properties. Herein, we prepared super activated carbon (SuperC) through the activation of commercial activated carbon by KOH and evaluated its effect on dehydrogenation properties of 2LiNH2MgH2. Our studies show that doping with SuperC could effectively lower its dehydrogenation temperatures. For instance, 2LiNH2MgH2–10 wt% SuperC can release 4.86 wt% of hydrogen upon heating up to 300 °C with the onset and peak dehydrogenation temperatures of 71 °C and 168 °C, respectively. Moreover, the release of byproduct NH3 was successfully suppressed. Measurement of thermal diffusivity suggests that the enhanced dehydrogenation properties may be ascribed to the improved heat transfer for solid-solid reaction resulting from doping with SuperC.

Catalytic effect of SrTiO3 on the hydrogen storage behaviour of MgH2

Abstract The effects of SrTiO3 on the hydrogen storage properties of MgH2 have been studied for the first time. The onset dehydrogenation temperature of the MgH2-10 wt% SrTiO3 is found to be 275 °C, which is 55 °C lower as compared to the as-milled MgH2. The composite is able to absorb 4.3 wt% of hydrogen in 60 min instead of 1.1 wt% for the as-milled MgH2. Meanwhile, the composite is able to release 5.3 wt% of hydrogen in 17 min compared to 1.9 wt% by the as-milled MgH2 at 320 °C. The calculated Ea of the MgH2-10 wt% SrTiO3 is 109 kJ/mol, which is 26.3 kJ/mol lower than the calculated Ea of the as-milled MgH2. The SrTiO3 is not decomposed during the ball milling and the re/dehydrogenation processes. The catalytic effect shown by the SrTiO3 is owing to its ability to change the physical structure of the MgH2 particles during the ball milling process.

Preparations and de/re-hydrogenation properties of LixNa3-xAlH6 (x=0.9–1.3) non-stoichiometric compounds

Mixed alkali alanates LixNa3-xAlH6 have been successfully synthesized by means of grinding mixtures of Li3AlH6 and Na3AlH6 in specific molar ratios. Non-stoichiometric LixNa3-xAlH6 compounds with single perovskite-type structures (space group Fm-3m) can be formed only within the composition range of x = 0.9–1.3. Li1.3Na1.7AlH6 exhibits superior hydrogen storage properties over other LixNa3-xAlH6 compounds. Its onset dehydrogenation temperature (∼423 K) was lowered by more than 40 K from other samples in temperature programmed dehydrogenation (TPD) curves. Also, the dehydrogenation capacity of Li1.3Na1.7AlH6 (3.45 wt.%) is the highest among the compounds. The dehydrogenation enthalpy values of LixNa3-xAlH6 decreased as x increased from 0.9 to 1.3 according to the results by isothermal pressure-composition (PCI) curves and van't Hoff plots. It shows that the dehydrogenation Li1.3Na1.7AlH6 (49.7 kJ mol H2−1) was greatly destabilized from that of LiNa2AlH6 (68.1 kJ mol H2−1). Furthermore, the apparent activation energy of dehydrogenation for Li1.3Na1.7AlH6 (138.1 kJ mol−1) was remarkably lowered from that of LiNa2AlH6. This illustrates that Li1.3Na1.7AlH6 exhibits enhanced dehydrogenation kinetics from that of LiNa2AlH6.