Catalytic effects of FGO-Ni addition on the dehydrogenation properties of LiAlH4

LiAlH₄ is an ideal hydrogen storage material with a theoretical hydrogen storage capacity of 10.6 wt%. In order to reduce the hydrogen release temperature and increase the hydrogen release amount of LiAlH₄, multilayer graphene oxide and nickel (FGO-Ni) composite catalyst were prepared by physical ball milling and doped into LiAlH₄. The effect of FGO-Ni composite catalyst on the dehydrogenation performance of LiAlH₄ was studied by pressure-composition-temperature apparatus, scanning electron microscope (SEM) and X-ray diffractometer. The results show that, compared with pure LiAlH₄, the hydrogen release time of LiAlH₄ doped with 9 wt%FGO-3wt%Ni is obviously shortened about 90min at 150 °C and the hydrogen release amount of LiAlH₄ doped with 9 wt%FGO-3wt%Ni also increased 1.8 wt%. Importantly, the dehydrogenation amount of LiAlH₄ (9 wt%FGO)-3wt% could reach 4 wt% at 135 °C which was 4 times higher than that of the pure LiAlH₄. At the same temperature, the hydrogen release of pure LiAlH₄ was only 0.84 wt%. In contrast, doping FGO-Ni composite catalyst reduces the hydrogen release temperature of LiAlH₄ and weakens the hydrogen release barrier. Forthermore, SEM results showed that doping FGO-Ni reduced the agglomeration between LiAlH₄ particles and increased the specific surface area of the sample, which improving the hydrogen release properties of LiAlH₄.     

Ultra-fast dehydrogenation behavior at low temperature of LiAlH4 modified by fluorographite

LiAlH₄ modified by different weight ratios of fluorographite (FGi) can be synthesized through mechanical ball-milling and their dehydrogenation behaviors were investigated. LiAlH₄ particles distributed on the FGi surface with greatly decreased sizes are achieved, comparing with ball-milled pristine LiAlH₄. Greatly reduced dehydrogenation temperatures are discovered in LiAlH₄-FGi composites. Among these composites, LiAlH₄-40FGi composite exhibits an ultra-fast hydrogen release at very low temperature as 61.2 °C, and 5.7 wt% hydrogen is liberated in seconds. Besides, the released hydrogen is of high purity according to MS test. Furthermore, XRD analysis on the dehydrogenated products proves that FGi changes the dehydrogenation reaction pathway of LiAlH₄, through which the dehydrogenation reaction enthalpy change is remarkably reduced, leading to greatly improved hydrogen desorption properties. Such investigations have discovered the potential of solid-state way of producing hydrogen under ambient temperatures.     

Enhanced hydrogen storage performance of LiAlH4-MgH2-TiF3 composite

The mutual destabilization of LiAlH₄ and MgH₂ in the reactive hydride composite LiAlH₄-MgH₂ is attributed to the formation of intermediate compounds, including Li-Mg and Mg-Al alloys, upon dehydrogenation. TiF₃ was doped into the composite for promoting this interaction and thus enhancing the hydrogen sorption properties. Experimental analysis on the LiAlH₄-MgH₂-TiF₃ composite was performed via temperature-programmed desorption (TPD), differential scanning calorimetry (DSC), isothermal sorption, pressure-composition isotherms (PCI), and powder X-ray diffraction (XRD). For LiAlH₄-MgH₂-TiF₃ composite (mole ratio 1:1:0.05), the dehydrogenation temperature range starts from about 60 °C, which is 100 °C lower than for LiAlH₄-MgH₂. At 300 °C, the LiAlH₄-MgH₂-TiF₃ composite can desorb 2.48 wt% hydrogen in 10 min during its second stage dehydrogenation, corresponding to the decomposition of MgH₂. In contrast, 20 min was required for the LiAlH₄-MgH₂ sample to release so much hydrogen capacity under the same conditions. The hydrogen absorption properties of the LiAlH₄-MgH₂-TiF₃ composite were also improved significantly as compared to the LiAlH₄-MgH₂ composite. A hydrogen absorption capacity of 2.68 wt% under 300 °C and 20 atm H₂ pressure was reached after 5 min in the LiAlH₄-MgH₂-TiF₃ composite, which is larger than that of LiAlH₄-MgH₂ (1.75 wt%). XRD results show that the MgH₂ and LiH were reformed after rehydrogenation.     

Thermal decomposition of LiAlH4 chemically mixed with Lithium amide and transition metal chlorides

Thermogravimetric analysis of LiAlH₄ chemically mixed with different additives is reported for the application of hydrogen storage. Here, we illustrated the dehydrogenation properties of combined LiAlH₄/LiNH₂ (2:1) mixture and LiAlH₄ wet-doped with different transition metals (Sc, Ti, and V) in their chloride forms. Thermal gravimetric analysis of LiAlH₄/LiNH₂ system released 7.9 wt.% of hydrogen in three decomposition steps at temperatures between 75 and 280 °C under a heating ramp of 5 °C min⁻¹. The LiAlH₄ doped with transition metals showed the decrease of decomposition temperature down to 30–40 °C for both 1st and 2nd dehydrogenation steps as compared to as-received LiAlH₄. The catalytic activity in lowering the dehydrogenation temperature of LiAlH₄ doped with transition metals increases in the order of pure LiAlH₄ < V < Ti < Sc. The X-ray diffraction analysis, field emission scanning electron microscopy, and Fourier transformation infra-red spectroscopy techniques were carried out in support of the thermogravimetric results.     

LiAlH4–ZrCl4 mixtures for hydrogen release at near room temperature

The dehydrogenation temperature of LiAlH₄ was significantly reduced by the production of mixtures with ZrCl₄. Stoichiometric 4:1, and 5 mol % mixtures of LiAlH₄ and ZrCl₄ were produced by ball milling at room temperature and ?196 °C, and tested for dehydrogenation at low temperature. Cryogenic ball-milling resulted in an effective way to produce reactive mixtures for hydrogen release; because of achieving small aggregates size (5–20 μm) in 10 min of cryomilling while preventing substantial decomposition during preparation. Dehydrogenation reaction in the mixtures LiAlH₄/ZrCl₄ started around 31–47 °C under different heating rates. Partial dehydrogenation was proved at 70 °C: 4.4 wt % for the 5 mol% ZrCl₄–LiAlH₄ mixture, and 3.4 wt % for the best 4:1 stoichiometric mixture. Complete dehydrogenation up to 250 °C released 6.4 wt% and 4.1 wt%, respectively. Dehydrogenation reactions are exothermic, and the LiAlH₄/ZrCl₄ mixtures are unstable and difficult to handle. The activation energy of the exothermic reactions was estimated as 113.5 ± 9.8 kJ/mol and 40.6 ± 6.6 kJ/mol for 4LiAlH₄+ZrCl₄ and 5%mol ZrCl₄+LiAlH₄ samples milled in cryogenic conditions, respectively. The dehydrogenation pathway was changed in the LiAlH₄/ZrCl₄ mixtures as compared to pure LiAlH₄. Dehydrogenation reaction is proposed to form Al, LiCl, Zr, and H₂ as main products. Modification of the dehydrogenation reaction of LiAlH₄ was achieved at the cost of reducing the total hydrogen release capacity.     

Enhancing the dehydrogenation properties of LiAlH4 using K2NiF6 as additive

Lithium alanate (LiAlH₄) is a material that can be potentially used for solid-state hydrogen storage due to its high hydrogen content (10.5 wt%). Nevertheless, a high desorption temperature, slow desorption kinetic, and irreversibility have restricted the application of LiAlH₄ as a solid-state hydrogen storage material. Hence, to lower the decomposition temperature and to boost the dehydrogenation kinetic, in this study, we applied K₂NiF₆ as an additive to LiAlH₄. The addition of K₂NiF₆ showed an excellent improvement of the LiAlH₄ dehydrogenation properties. After adding 10 wt% K₂NiF₆, the initial decomposition temperature of LiAlH₄ within the first two dehydrogenation steps was lowered to 90 °C and 156 °C, respectively, that is 50 °C and 27 °C lower than that of the аs-milled LiAlH₄. In terms of dehydrogenation kinetics, the dehydrogenation rate of K₂NiF₆-doped LiAlH₄ sample was significantly higher as compared to аs-milled LiAlH₄. The K₂NiF₆-doped LiAlH₄ sample can release 3.07 wt% hydrogen within 90 min, while the milled LiAlH₄ merely release 0.19 wt% hydrogen during the same period. According to the Arrhenius plot, the apparent activation energies for the desorption process of K₂NiF₆-doped LiAlH₄ are 75.0 kJ/mol for the first stage and 88.0 kJ/mol for the second stage. These activation energies are lower compared to the undoped LiAlH₄. The morphology study showed that the LiAlH₄ particles become smaller and less agglomerated when K₂NiF₆ is added. The in situ formation of new phases of AlNi and LiF during the dehydrogenation process, as well as a reduction in particle size, is believed to be essential contributors in improving the LiAlH₄ dehydrogenation characteristics.     

Enhanced hydrogen storage properties of TiN–LiAlH4 composite

The hydrogen storage properties of LiAlH₄ doped efficient TiN catalyst were systematically investigated. We observe that TiN catalyst enhances the dehydrogenation kinetics and decreases the dehydrogenation temperature of LiAlH₄. The dehydrogenation behaviors of 2%TiN–LiAlH₄ are investigated using temperature programmed desorption (TPD), differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FTIR). Interestingly, the onset hydrogen desorption temperature of 2%TiN–LiAlH₄ sample gets lowered from 151.0 °C to 90.0 °C with a faster kinetics, and the dehydrogenation rate reached a maximum value at 137.2 °C. By adding a small amount of as-prepared TiN, approximately 7.1 wt% of hydrogen can be released from the LiAlH₄ at 130 °C. Interestingly, the result of the FTIR indicates that the 2%TiN–LiAlH₄ maybe restore hydrogen under 5.5 MPa hydrogen. Moreover, 2%TiN–LiAlH₄ displayed a substantially reduced activation energy for LiAlH₄ dehydrogenation.     

Comparative study on the dehydrogenation properties of TiCl4-doped LiAlH4 using different doping techniques

Lithium aluminum hydride (LiAlH₄) is an attractive hydrogen storage material because of its comparatively high gravimetric hydrogen storage capacity. In this study, titanium tetrachloride (TiCl₄), which is liquid at room temperature, was chosen as dopant because of its high catalytic efficiency regarding the dehydrogenation of LiAlH₄. Three low-energy doping methods (additive dispersion via ball milling at low rotation speed, magnetic stirring and magnetic stirring in ethyl ether) with different TiCl₄ concentrations were compared in order to obtain optimum dehydrogenation properties of LiAlH₄. At 80 °C, TiCl₄-doped LiAlH₄ can release up to 6.5 wt.%-H₂, which opens the way to use of exhaust heat of PEM fuel cells to trigger the hydrogen release from LiAlH₄.     

Significantly improved dehydrogenation of LiAlH4 destabilized by K2TiF6

The effects of K₂TiF₆ on the dehydrogenation properties of LiAlH₄ were investigated by solid-state ball milling. The onset decomposition temperature of 0.8 mol% K₂TiF₆ doped LiAlH₄ is as low as 65 °C that 85 °C lower than that of pristine LiAlH₄. Isothermal dehydrogenation properties of the doped LiAlH₄ were studied by PCT (pressure–composition–temperature). The results show that, for the 0.8 mol% K₂TiF₆ doped LiAlH₄ that dehydrogenated at 90 °C, 4.4 wt% and 6.0 wt% of hydrogen can be released in 60 min and 300 min, respectively. When temperature was increased to 120 °C, the doped LiAlH₄ can finish its first two dehydrogenation steps in 170 min. DSC results show that the apparent activation energy (E_a) for the first two dehydrogenation steps of LiAlH₄ are both reduced, and XRD results suggest that TiH₂, Al₃Ti, LiF and KH are in situ formed, which are responsible for the improved dehydrogenation properties of LiAlH₄.     

Improved reversible hydrogen storage of LiAlH4 by nano-sized TiH2

Transition metal halides are mostly used as dopants to improve the hydrogen storage properties of LiAlH₄, but they will cause hydrogen capacity loss because of their relatively high molecular weights and reactions with LiAlH₄. To overcome these drawbacks, active nano-sized TiH₂ (TiH₂^nano) prepared by reactive ball milling is used to dope LiAlH₄. It shows superior catalytic effect on the dehydrogenation of LiAlH₄ compared to commercial TiH₂. TiH₂^nano-doped LiAlH₄ starts to release hydrogen at 75 °C, which is 80 °C lower than the onset dehydrogenation temperature of commercial LiAlH₄. About 6.3 wt.% H₂ can be released isothermally at 100 °C (800 min) or at 120 °C (150 min). The apparent activation energies of the first two dehydrogenation reactions of LiAlH₄ are reduced by about 20 and 24 kJ mol⁻¹, respectively. Meanwhile, the regeneration of LiAlH₄ is realized through extracting the solvent from LiAlH₄·4THF, which is obtained by ball milling the dehydrogenated products of TiH₂^nano-doped LiAlH₄ in the presence of THF and 5 MPa H₂. This suggests that TiH₂ is also an effective catalyst for the formation of LiAlH₄·4THF.     

Enhanced dehydrogenation and rehydrogenation properties of LiBH4 catalyzed by graphene

The investigation of thermally induced dehydrogenation of LiBH₄ reveals that LiBH₄ doped with the graphene catalysts shows superior dehydrogenation and rehydrogenation performance to that of Vulcan XC-72, carbon nanotube and BP2000 doped LiBH₄. For doping with 20 wt.% graphene, thermal dehydrogenation of LiBH₄ is found to start at ca. 230 °C and a total weight loss of 11.4 wt.% can be obtained below 700 °C. With increased loading of graphene within a LiBH₄ sample, the onset dehydrogenation temperature and the two main desorption peaks from LiBH₄ are found to decrease while the hydrogen release amount is found to increase. Moreover, variation of the equilibrium pressure obtained from isotherms measured at 350–450 °C indicate the dehydrogenation enthalpy is reduced from 74 kJ mol⁻¹ H₂ for pure LiBH₄ to ca. 40 kJ mol⁻¹ H₂ for 20 wt.% graphene doped LiBH₄. Importantly, the reversible dehydrogenation/rehydrogenation process was achieved under 3 MPa H₂ at 400 °C for 10 h, with a capacity of ca. 4.0 wt.% in the tenth cycle. Especially, LiBH₄ is reformed and new species, Li₂B₁₀H₁₀, is detected after the rehydrogenation process.     

Enhancement of the H2 desorption properties of LiAlH4 doping with NiCo2O4 nanorods

Lithium aluminum hydride (LiAlH₄) is considered as an attractive candidate for hydrogen storage owing to its favorable thermodynamics and high hydrogen storage capacity. However, its reaction kinetics and thermodynamics have to be improved for the practical application. In our present work, we have systematically investigated the effect of NiCo₂O₄ (NCO) additive on the dehydrogenation properties and microstructure refinement in LiAlH₄. The dehydrogenation kinetics of LiAlH₄ can be significantly increased with the increase of NiCo₂O₄ content and dehydrogenation temperature. The 2 mol% NiCo₂O₄-doped LiAlH₄ (2% NCO–LiAlH₄) exhibits the superior dehydrogenation performances, which releases 4.95 wt% H₂ at 130 °C and 6.47 wt% H₂ at 150 °C within 150 min. In contrast, the undoped LiAlH₄ sample just releases <1 wt% H₂ after 150 min. About 3.7 wt.% of hydrogen can be released from 2% NCO–LiAlH₄ at 90 °C, where total 7.10 wt% of hydrogen is released at 150 °C. Moreover, 2% NCO–LiAlH₄ displayed remarkably reduced activation energy for the dehydrogenation of LiAlH₄.     

Effects of REF3 (RE = Y,La, Ce) additives on dehydrogenation properties of LiAlH4

The catalytic effects of rare earth fluoride REF₃ (RE = Y, La, Ce) additives on the dehydrogenation properties of LiAlH₄ were carefully investigated in the present work. The results showed that the dehydrogenation behaviors of LiAlH₄ were significantly altered by the addition of 5 mol% REF₃ through ball milling. The destabilization ability of these catalysts on LiAlH₄ has the order: CeF₃>LaF₃>YF₃. For instance, the temperature programmed desorption (TPD) analyses showed that the onset dehydrogenation temperature of CeF₃ doped LiAlH₄ was sharply reduced by 90 °C compared to that of pristine LiAlH₄. Based on differential scanning calorimetry (DSC) analyses, the dehydriding activation energies of the CeF₃ doped LiAlH₄ sample were 40.9 kJ/mol H₂ and 77.2 kJ/mol H₂ for the first and second dehydrogenation stages, respectively, which decreased about 40.0 kJ/mol H₂ and 60.3 kJ/mol H₂ compared with those of pure LiAlH₄. In addition, the sample doped with CeF₃ showed the fastest dehydrogenation rate among the REF₃ doped LiAlH₄ samples at both 125 °C and 150 °C during the isothermal desorption. The phase changes in REF₃ doped LiAlH₄ samples during ball milling and dehydrogenation were examined using X-ray diffraction and the mechanisms related to the catalytic effects of REF₃ were proposed.     

Low-temperature hydrogen release through LiAlH4 and NH4F react in Et2O

The application of hydrogen energy urgently requires a high-capacity hydrogen storage technology that can release hydrogen at low temperature. The composite of LiAlH₄ and NH₄F has a hydrogen storage capacity of up to 8.06 wt%, but the release of hydrogen requires a reaction temperature of about 170 °C, and the reaction is difficult to control. In this work, the reaction between LiAlH₄ and NH₄F is proposed to be carried out in diethyl ether to improve its hydrogen release performance. It exhibits good hydrogen release performance over a wide temperature range of −40–25 °C, and the hydrogen release capacity at −40 °C, −20 °C, 0 °C and 25 °C can reach 4.41 wt%, 6.79 wt%, 6.85 wt% and 7.78 wt%, respectively. The activation energy of the reaction is 38.41 kJ mol⁻¹, which is much lower than many previously reported catalytic hydrolysis systems that can release hydrogen at room temperature. Our study demonstrates a high-performance hydrogen storage system with very low operating temperature, which may lay the foundation for the development of practical mobile/portable hydrogen source in the north and the Arctic.     

LiBH4–VCl3 and LiAlH4–VCl3 mixtures prepared in soft milling conditions for hydrogen release at low temperature

Mixtures of LiBH₄/VCl₃ and LiAlH₄/VCl₃ in 5:1, 3:1, and 5% mol stoichiometries were prepared and tested for hydrogen release. The mixtures were prepared in 10 min of ball milling at room temperature or with cryogenic (N₂-liquid) cooling. The mixtures demonstrated diverse hydrogen release levels, but all of them started releasing hydrogen at low temperatures (33–66 °C) with a change in the reaction pathway as compared to pure LiBH₄ or LiAlH₄. The driving force for that is the formation of the stable salt LiCl. The best material was the 5% mol VCl₃ + LiAlH₄ cryogenic mixture because of the low-temperature dehydrogenation onset of 34 °C; and the dehydrogenation level of 5.1 wt.%, and 6.4 wt.% that was achieved upon heating at 100 °C and 250 °C, respectively.     

Mechanochemical modification of LiAlH4 with Fe2O3 - A combined DFT and experimental study

LiAlH₄ is a promising material for hydrogen storage, having the theoretical gravimetric density of 10.6 wt% H₂. In order to decrease the temperature where hydrogen is released, we investigated the catalytic influence of Fe₂O₃ on LiAlH₄ dehydrogenation, as a model case for understanding the effects transition oxide additives have in the catalysis process. Quick mechanochemical synthesis of LiAlH₄ + 5 wt% Fe₂O₃ led to the significant decrease of the hydrogen desorption temperature, and desorption of over 7 wt%H₂ in the temperature range 143–154 °C. Density functional theory (DFT)-based calculations with Tran-Blaha modified Becke-Johnson functional (TBmBJ) address the electronic structure of LiAlH₄ and Li₃AlH₆. ⁵⁷Fe Mössbauer study shows the change in the oxidational state of iron during hydrogen desorption, while the ¹H NMR study reveals the presence of paramagnetic species that affect relaxation. The electron transfer from hydrides is discussed as the proposed mechanism of destabilization of LiAlH₄ + 5 wt% Fe₂O₃.     

Preparation of a new Ti catalyst for improved performance of NaAlH4

Three effective Ti catalysts for NaAlH₄ were made by stoichiometrically reacting TiCl₃ with LiAlH₄ in tetrahydrofuran (THF), NaAlH₄ in THF, and LiAlH₄ in diethyl ether (Et₂O). The solid products produced after drying were named ex situ catalysts and designated respectively as Ti(Li)T, Ti(Na)T and Ti(Li)E. NaAlH₄ was dry doped with 2 mol% of these ex situ catalysts, and for comparison, NaAlH₄ was conventionally wet doped with 2 mol% TiCl₃ in THF that made in situ catalyst (designated as TiCl₃). All four doped samples were dry ball milled, and hydrogenation and dehydrogenation studies were carried out over five cycles. Temperature programmed desorption, constant temperature desorption, and constant temperature cycling curves showed that the effectiveness of these catalysts decreased as Ti(Li)T > Ti(Na)T > TiCl₃ > Ti(Li)E. Ti(Li)T ex situ catalyst, being the best Ti catalyst, markedly decreased the dehydrogenation temperature, improved both the hydrogenation and dehydrogenation kinetics with sustained rates over cycling, and exhibited the least loss of hydrogen storage capacity over cycling. Ti(Li)T ex situ catalyst exhibited properties commensurate with some of the best NaAlH₄ catalysts to date, such as CeCl₃, ScCl₃ and Ti nanocluster. It is easy to make, readily available and relatively inexpensive.     

Recent advances in catalyst-enhanced LiAlH4 for solid-state hydrogen storage: A review

LiAlH₄ is regarded as a potential material for solid-state hydrogen storage because of its high hydrogen content (10.5 wt%). However, its high decomposition temperature, slow dehydrogenation kinetics and irreversibility under moderate condition hamper its wider applications. Mechanical milling treatment and doping with a catalyst or additive has drawn significant ways to improve hydrogen storage properties of LiAlH₄. Microstructure or nanostructure materials were developed by using a ball milling technique and doping with various types of catalysts or additives which had dramatically improved the efficiency of LiAlH₄. However, the state-of-the-art technologies is still far from meeting the expected goal for the applications. In this paper, the overview of the recent advances in catalyst-enhanced LiAlH₄ for solid-state hydrogen storage is detailed. The remaining challenges and the future prospect of LiAlH₄–catalyst system is also discussed. This paper is the first systematic review that focuses on catalyst-enhanced LiAlH₄ for solid-state hydrogen storage.     

Enhanced hydrogen storage properties of 4MgH2 + LiAlH4 composite system by doping with Fe2O3 nanopowder

In this paper, the hydrogen storage properties and reaction mechanism of the 4MgH₂ + LiAlH₄ composite system with the addition of Fe₂O₃ nanopowder were investigated. Temperature-programmed-desorption results show that the addition of 5 wt.% Fe₂O₃ to the 4MgH₂ + LiAlH₄ composite system improves the onset desorption temperature to 95 °C and 270 °C for the first two dehydrogenation stage, which is lower 40 °C and 10 °C than the undoped composite. The dehydrogenation and rehydrogenation kinetics of 5 wt.% Fe₂O₃-doped 4MgH₂ + LiAlH₄ composite were also improved significantly as compared to the undoped composite. Differential scanning calorimetry measurements indicate that the enthalpy change in the 4MgH₂–LiAlH₄ composite system was unaffected by the addition of Fe₂O₃ nanopowder. The Kissinger analysis demonstrated that the apparent activation energy of the 4MgH₂ + LiAlH₄ composite (125.6 kJ/mol) was reduced to 117.1 kJ/mol after doping with 5 wt.% Fe₂O₃. Meanwhile, the X-ray diffraction analysis shows the formation of a new phase of Li₂Fe₃O₄ in the doped composite after the dehydrogenation and rehydrogenation process. It is believed that Li₂Fe₃O₄ acts as an actual catalyst in the 4MgH₂ + LiAlH₄ + 5 wt.% Fe₂O₃ composite which may promote the interaction of MgH₂ and LiAlH₄ and thus accelerate the hydrogen sorption performance of the MgH₂ + LiAlH₄ composite system.     

Ti-doped LiAlH4 for hydrogen storage: Rehydrogenation process,reaction conditions and microstructure evolution during cycling

One-step rehydrogenation of Ti-doped LiAlH₄ from its dehydrogenated precursor (Ti-doped LiH/Al), proceeds in Me₂O solution under mild conditions (25 °C; 50–100 bar H₂). The formation process, the effects of reaction conditions (temperature and H₂ pressure) on the yield of LiAlH₄, and the microstructure evolution during hydrogenation–dehydrogenation cycles were investigated comprehensively. No evidence was obtained for the intermediate Li₃AlH₆ in the product. Higher temperatures adversely affect the yield and stability of the Ti-doped LiAlH₄ product. High hydrogen pressure favors the formation of LiAlH₄ but the influence of pressure in the range 50–100 bar is slight if other variables are maintained constant. The cycling performance depends on the microstructure of the material: larger particle size; lower surface area; and the formation of less active Ti clusters and Ti–Al alloys upon cycling correspond to a decrease in cycling performance. Incorporation of an extra ball milling stage before each rehydrogenation significantly improves the cycling performance.