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The intermittent nature of renewable energy generation can be tackled by integrating them with electrochemical energy storage, which can also close the gap between supply and demand effectively. It has recently been demonstrated that Si3N4‐based negative electrodes are a promising option for lithium‐ion batteries due to their large theoretical capacity and appropriate working potential with extremely low polarization. In the present work, Si3N4 was utilized as anode material in all‐solid‐state lithium‐ion battery with lithium borohydride as a solid electrolyte and Li foil placed as a counter electrode. The electrochemical properties were investigated using galvanostatic charge/discharge profiling whereas the mechanism of lithiation delithiation was investigated in detail using x‐ray diffraction (XRD). The highest capacity of the composite materials was obtained as 1700 mAhg−1 at 0.05 C current rate in the first cycle, which is reduced to 370 in 5 cycles. However, a stability in the capacity was observed in subsequent cycles and a retention of almost 88% could be achieved in 150 cycles. The interfacial resistance before and after the electrochemical cycling was observed as 326 Ω and 13 kΩ, respectively which is also supported by the microstructural investigations where the cracks are observed because of thermochemical reactions. [ABSTRACT FROM AUTHOR]

LiBH4 with high hydrogen storage density, is regarded as one of the most promising hydrogen storage materials. Nevertheless, it suffers from high dehydrogenation temperature and poor reversibility for practical use. Nanoconfinement is effective in achieving low dehydrogenation temperature and favorable reversibility. Besides, graphene can serve as supporting materials for LiBH4 catalysts and also destabilize LiBH4 via interfacial reaction. However, graphene has never been used alone as a frame material for nanoconfining LiBH4. In this study, graphene microflowers with large pore volumes were prepared and used as nanoconfinement framework material for LiBH4, and the nanoconfinement effect of graphene was revealed. After loading 70 wt% of LiBH4 and mechanically compressed at 350 MPa, 8.0 wt% of H2 can be released within 100 min at 320 °C, corresponding to the highest volumetric hydrogen storage density of 94.9 g H2 L-1 ever reported. Thanks to the nanoconfinement of graphene, the rate-limiting step of dehydrogenation of nanoconfined LiBH4 was changed and its apparent activation energy of the dehydrogenation (107.3 kJ moL-1) was 42% lower than that of pure LiBH4. Moreover, the formation of the intermediate Li2B12H12 was effectively inhibited, and the stable nanoconfined structure enhanced the reversibility of LiBH4. This work widens the understanding of graphene's nanoconfinement effect and provides new insights for developing high-density hydrogen storage materials. [ABSTRACT FROM AUTHOR]

In the present work, single, double and triaxial (tensile/compression) strains were applied to lithium borohydride LiBH 4 using Density Functional Theory (DFT) based on Perdew-Burke-Ernzerhor for solids (PBEsol) approach. The results show that the structural properties change with the deformation amplitude. The total density of state (TDOS) and partial density of state (PDOS) studies show that the LiBH 4 complex hydride is an insulator with an energy band gap of 6.73 eV and the width of the valence and conduction bands vary with the change of the strain amplitude. The deformation energy shows that triaxial deformation on LiBH 4 complex hydride requires more energy than single and double strains. Hence, these deformations are found responsible for the decrease of the thermodynamic properties of LiBH 4 hydride. Specifically, under a maximum uni/bi/triaxial compressive strain of ε = −9%, the enthalpy of formation and decomposition temperature decrease by 3.25 %, 7.59 %, and 36.54 %, respectively. While, under a maximum uni/bi/triaxial tensile strain of ε = +9 %, the enthalpy of formation and decomposition temperature decrease by 3.85 %, 11.83 %, and 26.44 %, respectively, compared to unstrained hydride. Consequently, the findings are in excellent agreement with the standards of the U.S. Department of Energy (DOE) (ΔH f = −40 Kj/mol.H 2 and T d = 289–393 K) for hydrogen storage in the solid state. • Study of the thermodynamic properties of LiBH 4 under deformation conditions. • Compressive deformation improves the hydrogen storage performances of LiBH 4. • The results comply with the criteria imposed by the DOE (Department of Energy) for practical applications of H 2 storage. [ABSTRACT FROM AUTHOR]

This paper highlights the hydrogen storage performance of surface oxidized LiBH 4 (Lithium borohydride) system incorporated with NiO nanostructures under 250 °C. Surface oxidized LiBH 4 system was impregnated with hydrothermally synthesized mesoporous NiO nanorods (NiONR) and NiO nanoplates (NiONP) using simple ultrasonication method. Hydrogen sorption and desorption studies has been investigated for LiBH 4 /NiONR and LiBH 4 /NiONP systems for the first time. The Brunauer-Emmett-Teller results showed that the specific surface area of NiONR, NiONP, LiBH 4 /NiONR and LiBH 4 /NiONP systems were 77.92, 88.12, 96.67 and 101.65 m2/g, respectively. Hydrogenation followed by isothermal dehydrogenation at 250 °C revealed that the LiBH 4 /NiONR and LiBH 4 /NiONP systems released ∼3.44 wt% and 4.02 wt% of hydrogen respectively in 60 min. Using the Kissinger's relation, the activation energy (E a) was calculated as 69.28 and 63.23 kJ/mol for LiBH 4 /NiONR and LiBH 4 /NiONP systems, respectively. The dehydrogenation rate of LiBH 4 /NiONP system was found to be greater than that of LiBH 4 /NiONR system due to its large surface area and lower activation energy. The reported results revealed that nickel oxide nanostructures incorporated surface oxidized LiBH 4 systems provide new opportunities for the solid-state hydrogen storage applications. [Display omitted] • Hydrogen sorption/desorption studies were investigated for the LiBH 4 /NiO systems. • The surface area of LiBH 4 /NiONR and LiBH 4 /NiONP are 96.7 and 101.6 m2/g respectively. • LiBH 4 /NiONP and LiBH 4 /NiONR desorb 4.0 and 3.4 wt% of hydrogen at 250 °C in 1 h. [ABSTRACT FROM AUTHOR]

In this work, the combined effects of anion substitution (with Br− and I−) and SiO2 addition on the Li-ion conductivity in LiBH4 have been investigated. Hexagonal solid solutions with different compositions, h-Li(BH4)1−α(X)α (X = Br, I), were prepared by ball milling and fully characterized. The most conductive composition for each system was then mixed with different amounts of SiO2 nanoparticles. If the amount of added complex hydride fully fills the original pore volume of the added silica, in both LiBH4-LiBr/SiO2 and LiBH4-LiI/SiO2 systems, the Li-ion conductivity was further increased compared to the h-Li(BH4)1−α(X)α solid solutions alone. The use of LiBH4-LiX instead of LiBH4 in composites with SiO2 enabled the development of an optimal conductive pathway for the Li ions, since the h-Li(BH4)1−α(X)α possesses a higher conductivity than LiBH4. In fact, the Li conductivity of the silica containing h-Li(BH4)1−α(X)α is higher than the maximum reached in LiBH4-SiO2 alone. Therefore, a synergetic effect of combining halogenation and interface engineering is demonstrated in this work. [ABSTRACT FROM AUTHOR]

In this paper, the methods used to enhance the conductivity of LiBH4, a potential electrolyte for the construction of solid-state batteries, are summarized. Since this electrolyte becomes conductive at temperatures above 380 K due to a phase change, numerous studies have been conducted to lower the temperature at which the hydride becomes conductive. An increase in conductivity at lower temperatures has generally been obtained by adding a second component that can increase the mobility of the lithium ion. In some cases, conductivities at room temperature, such as those exhibited by the liquid electrolytes used in current lithium-ion batteries, have been achieved. With these modified electrolytes, both lithium metal and lithium-ion cells have also been constructed, the performances of which are reported in the paper. In some cases, cells characterized by a high capacity and rate capability have been developed. Although it is still necessary to confirm the stability of the devices, especially in terms of cyclability, LiBH4-based doped electrolytes could be employed to produce solid-state lithium or lithium-ion batteries susceptible to industrial development. [ABSTRACT FROM AUTHOR]

In this work, the combined effects of anion substitution (with Br− and I−) and SiO2 addition on the Li-ion conductivity in LiBH4 have been investigated. Hexagonal solid solutions with different compositions, h-Li(BH4)1−α(X)α (X = Br, I), were prepared by ball milling and fully characterized. The most conductive composition for each system was then mixed with different amounts of SiO2 nanoparticles. If the amount of added complex hydride fully fills the original pore volume of the added silica, in both LiBH4-LiBr/SiO2 and LiBH4-LiI/SiO2 systems, the Li-ion conductivity was further increased compared to the h-Li(BH4)1−α(X)α solid solutions alone. The use of LiBH4-LiX instead of LiBH4 in composites with SiO2 enabled the development of an optimal conductive pathway for the Li ions, since the h-Li(BH4)1−α(X)α possesses a higher conductivity than LiBH4. In fact, the Li conductivity of the silica containing h-Li(BH4)1−α(X)α is higher than the maximum reached in LiBH4-SiO2 alone. Therefore, a synergetic effect of combining halogenation and interface engineering is demonstrated in this work.

Electrochemical energy storage is considered a remarkable way to bridge the gap between demand and supply due to intermittent renewable energy production. All-solid-state batteries are an excellent alternative and are known to be the safest class of batteries. In the present scenario to accomplish the energy demands, high-capacity and stable anodes are warranted and can play a vital role in technology upgradation. Among the variety of anodes, alloying-type anodes are superior due to their high gravimetric capacity and stability. In the present work, zinc metal was implemented as electrode material in an all-solid-state lithium-ion battery. This anode material was tested with two different solid-state electrolytes, i.e., lithium borohydride (LiBH4) and halide-stabilized LiBH4 (i.e., LiBH4.LiI). In a coin cell, Li foil was placed as a counter electrode. The establishment of a reaction mechanism during the charging and discharging was obtained through X-ray diffraction (XRD) and cyclic voltammetry (CV). Systematic studies using the temperature dependence performance were also conducted. The volumetric density with both electrolytes was found at more than 3000 mAh/cm3. The coulombic efficiency for the electrode material was also observed at ~94%. These impressive numbers present zinc electrodes as a promising material for future electrode material for all-solid-state Li-ion batteries. [ABSTRACT FROM AUTHOR]

In this paper, the methods used to enhance the conductivity of LiBH4, a potential electrolyte for the construction of solid-state batteries, are summarized. Since this electrolyte becomes conductive at temperatures above 380 K due to a phase change, numerous studies have been conducted to lower the temperature at which the hydride becomes conductive. An increase in conductivity at lower temperatures has generally been obtained by adding a second component that can increase the mobility of the lithium ion. In some cases, conductivities at room temperature, such as those exhibited by the liquid electrolytes used in current lithium-ion batteries, have been achieved. With these modified electrolytes, both lithium metal and lithium-ion cells have also been constructed, the performances of which are reported in the paper. In some cases, cells characterized by a high capacity and rate capability have been developed. Although it is still necessary to confirm the stability of the devices, especially in terms of cyclability, LiBH4-based doped electrolytes could be employed to produce solid-state lithium or lithium-ion batteries susceptible to industrial development.

• Ti + O co-doped LiBH 4 are introduced by Ti substitution for Li and O for B/H. • Modification of Ti + O on enhanced dehydrogenation of LiBH 4 depends on occupation sites. • Decrease of Li − B/H and B − H interactions leads to destabilized LiBH 4 for favorable H-desorption. • Formation of Ti − H and O − H bonds acts as thermodynamic force for LiBH 4 destabilization. The present work gives the occupation energies, hydrogen dissociation energies and electronic structures of pure (Li 8 B 8 H 32 /Li 16 B 16 H 64), Ti-doped (Li 7 TiB 8 H 32 /Li 15 TiB 16 H 64) and Ti + O co-doped LiBH 4 (Li 7 TiB 7 OH 32 /Li 15 TiB 15 OH 64 and Li 7 TiB 8 OH 31 /Li 15 TiB 16 OH 63) using first-principles calculations, with the aim of providing new insights into the enhanced dehydrogenation of LiBH 4 modified by Ti and O. The results show that Ti + O incorporation in LiBH 4 lattice is energetically favorable in terms of occupation energy, relative to Ti adding. Ti and Ti + O modification not only suppresses B 2 H 6 formation upon H-desorption, but also destabilizes LiBH 4 for favorable H-desorption. The decreased B − H and Li − B/H interactions contributes to LiBH 4 destabilization, and the formed Ti − H and O H bonds acts as thermodynamic driving force for this destabilization. In our studies, Ti + O enable hydrogen dissociation energy to reach the minimum at Li 7 TiB 7 OH 32 /Li 15 TiB 15 OH 64 not at Li 7 TiB 8 OH 31 /Li 15 TiB 16 OH 63. Thus, suitable Ti + O co-substitution is needed to achieve significant enhancement in LiBH 4 dehydrogenation. [ABSTRACT FROM AUTHOR]

Hydrogen energy has been recognized as “Ultimate Power Source” in the 21st century. It is a boon in these days of energy crunches and concerns about climate change because of the characterized advantages, such as high energy density, large calorific value, abundant resource, zero pollution, zero carbon emission, storable and renewable. State-of-the-art perspectives on tuning the stable thermodynamics and sluggish kinetics of dehydrogenation and re-hydrogenation of LiBH4, which has been regarded as a promising hydrogen storage alternative for onboard energy carrier applications have been discussed. Five major technological approaches are involved, including nanoengineering, catalyst modification, ions substitution, reactant destabilization and a novel process termed as high-energy ball milling with in-situ aerosol spraying (BMAS). It is worth noting that BMAS has the potential to help overcome the kinetic barriers for thermodynamically favorable systems like LiBH4 ​+ ​MgH2 mixture and provide thermodynamic driving force to enhance hydrogen release at a lower temperature.

LiBH 4 (LB in short) with a hydrogen capacity as high as 18.5 wt% and a low molecular weight (21.78 g mol−1) is among the most promising candidates for the hydrogen-based economy. However, current major technologies in (re)generation of LB rely heavily on energy-intensive processes, which greatly prohibits practical scaling-up of applications. Here we report a sustainable and effective approach to (re)generate LB via converting renewable H+ in crystalline water into H-, achieving a desirable yield of ∼50%. This one-step synthesis method relies on the reaction between spent fuels, specifically LiBO 2 · x H 2 O, and Mg-based alloys to form LB under ambient atmosphere. Notably, our approach surpasses the efficiency of other conventional method, such as LiH-B-H 2 and MgH 2 -LiBO 2 systems, which not only bypasses the energy-intensive dehydration procedure of LiBO 2 · x H 2 O (∼470 ℃) but also eliminates the use of costly hydrides or high-pressure H 2. Our findings indicate that Mg participated in the regeneration process prior to Al in Mg-Al alloys and [BH 4 ]- is gradually evolved from other intermediate species [BH x (OH) 4- x ]- (x = 0, 1, 2, 3). By combining hydrogen release and efficient storage of hydrogen-rich substrate in a closed materials cycle, this study may shed light on a promising step toward application of renewable hydrogen in a fuel cell-based hydrogen economy. • A hydrogen cycle with the couple hydrolysis and regeneration of LiBH 4 is achieved in the present work. • The regeneration technology for LiBH 4 is not only energy and cost effective, but also circumvents the need for troublesome heat-wasting procedures and expensive hydrides. • The regeneration yield of LiBH 4 is 50%, sourcing its essential hydrogen from renewable water. • The study demonstrates the universal applicability of regenerating LiBH 4 through the utilization of Mg-based reducing agents and LiBO 2 · x H 2 O. [ABSTRACT FROM AUTHOR]

Electrochemical energy storage is considered a remarkable way to bridge the gap between demand and supply due to intermittent renewable energy production. All-solid-state batteries are an excellent alternative and are known to be the safest class of batteries. In the present scenario to accomplish the energy demands, high-capacity and stable anodes are warranted and can play a vital role in technology upgradation. Among the variety of anodes, alloying-type anodes are superior due to their high gravimetric capacity and stability. In the present work, zinc metal was implemented as electrode material in an all-solid-state lithium-ion battery. This anode material was tested with two different solid-state electrolytes, i.e., lithium borohydride (LiBH4) and halide-stabilized LiBH4 (i.e., LiBH4.LiI). In a coin cell, Li foil was placed as a counter electrode. The establishment of a reaction mechanism during the charging and discharging was obtained through X-ray diffraction (XRD) and cyclic voltammetry (CV). Systematic studies using the temperature dependence performance were also conducted. The volumetric density with both electrolytes was found at more than 3000 mAh/cm3. The coulombic efficiency for the electrode material was also observed at ~94%. These impressive numbers present zinc electrodes as a promising material for future electrode material for all-solid-state Li-ion batteries.

Hydrogen has become a promising energy source due to its efficient and renewable properties. Although promising, hydrogen energy has not been in widespread use due to the lack of high-performance materials for hydrogen storage. Previous studies have shown that the addition of Al-based compounds to LiBH4 can create composites that have good properties for hydrogen storage. In this work, the dehydrogenation performances of different composite systems of 2LiBH4+ M (M = Al, LiAlH4, Li3AlH6) were investigated. The results show that, under a ball to powder ratio of 25:1 and a rotation speed of 300 rpm, the optimum ball milling time is 50 h for synthesizing Li3AlH6 from LiH and LiAlH4. The three studied systems destabilized LiBH4 at relatively low temperatures, and the 2LiBH4-Li3AlH6 composite demonstrated excellent behavior. Based on the differential scanning calorimetry results, pure LiBH4 released hydrogen at 469°C. The dehydrogenation temperature of LiBH4 is 416°C for 2LiBH4-Li3AlH6 versus 435°C for 2LiBH4-LiAlH4 and 445°C for 2LiBH4-Al. The 2LiBH4-Li3AlH6, 2LiBH4-LiAlH4, and 2LiBH4-Al samples released 9.1, 8, and 5.7 wt.% of H2, respectively. Additionally, the 2LiBH4-Li3AlH6 composite released the 9.1 wt.% H2 within 150 min. An increase in the kinetics was achieved. From the results, it was concluded that 2LiBH4-Li3AlH6 exhibits the best dehydrogenation performance. Therefore, the 2LiBH4-Li3AlH6 composite is considered a promising hydrogen storage material.

Flexible, water-resistant, and air-stable hydrogen storage material (named PMMA-LiBH4/GMF), consisting of LiBH4 nanoparticles confined by poly (methylmethacrylate) (PMMA) and reduced graphene oxide (rGO) modified melamine foam (GMF), were prepared by a facile method. PMMA-LiBH4/GMF can recover original shape after compression at the strain of 50% and exhibits highly hydrophobic property (water contact angle of 123°). Owing to the highly hydrophobic property and protection of PMMA, PMMA-LiBH4/GMF demonstrates outstanding water-resistance and air-stability. Significantly, the onset dehydrogenation temperature of PMMA-LiBH4/GMF at first step is reduced to 94°C, which is 149°C less than that of LiBH4/GMF, and the PMMA-LiBH4/GMF desorbs 2.9 wt% hydrogen within 25 min at 250°C, which is obviously more than the dehydrogenation amount of LiBH4/GMF under the same conditions. It's our belief that the flexible, water-resistant and air-stable PMMA-LiBH4/GMF with a simple preparation route will provide a new avenue to the research of hydrogen storage materials.

Novel porous hollow carbon nanospheres (HCNS) have been synthesized and utilized as scaffold for LiBH 4 –Mg(BH 4) 2 eutectic borohydride (LMBH). Large loading amounts of LMBH (33, 50 and 67 wt%) have been melt-infiltrated into HCNS, and the significantly improved dehydrogenation properties have been discovered. The LMBH@HCNS composites not only exhibit high actual dehydrogenation amounts and fast hydrogen desorption rates, but also an increased reversible hydrogen storage capacities after three cycles without obvious degradation. Further structural tests have revealed that the over-infiltrated LMBH covering the spherical surface of HCNS could also contribute to the improved hydrogen storage behaviors, due to a strong interfacial adhesion effect that avoid LMBH from aggregation during de/rehydrogenation cycles. • High-loading nanoconfined LiBH 4 -Mg(BH 4) 2 composites are prepared. • Enhanced dehydrogenation properties are discovered in LMBH@HCNS composites. • Over-infiltrated LMBH in LMBH@HCNS composites can be realized. [ABSTRACT FROM AUTHOR]

Lithium borohydride (LiBH 4) has received much attention due to its high hydrogen density of 18.5 wt%. However, in the hydrolytic process for hydrogen supply, the sluggish kinetics of LiBH 4 and the agglomeration of by-product greatly limit its wide utilization. In this work, transition-metal chlorides (CoCl 2 , NiCl 2 , FeCl 3) are firstly adopted to explore the hydrogen liberation behaviors of LiBH 4. The hydrolysis kinetics can be well-controlled by tuning the concentration of chlorides. Among the above chlorides, CoCl 2 displays much faster reaction kinetics, delivering a hydrogen generation rate ranging from 421 to 41701 mL min−1 g−1 with a maximum conversion of 95.3%, much higher than the value of 225 mL min−1 g−1 H 2 with Pt–LiCoO 2. The maximum gravimetric hydrogen density may reach 8.7 wt% at H 2 O/LiBH 4 = 2–6 mol/mol. Furthermore, NH 3 is introduced to solve the issue of uncontrollable kinetics of LiBH 4 by forming its ammoniates, where LiBH 4 ·NH 3 catalyzed by CoCl 2 could stably release over 4350 mL g−1 H 2 per unit weight of LiBH 4 within 30 min at 40 °C, with a hydrogen density of ∼7.1 wt% and a hydrogen yield of 97.0%. Our approaches adopting non-noble metal chlorides are efficient and affordable for hydrogen supply to PEMFCs via hydrolysis of LiBH 4 -based materials. • LiBH 4 -based materials catalyzed by non-noble metal chlorides are investigated for the first time. • The gravimetric hydrogen density of LiBH 4 hydrolysis may reach 8.7 wt%. • The hydrolysis kinetics of LiBH 4 could be well-controlled by CoCl 2 solution. • The conversion yield of LiBH 4 ·NH 3 nearly reaches 97% with a gravimetric hydrogen density of ∼7.1 wt%. • The catalytic effect of CoCl 2 is better than NiCl 2 or FeCl 3.. [ABSTRACT FROM AUTHOR]

In the present study, an all-solid-state half-cell Li/ amorphous Si (a-Si) was fabricated using the guest Li+ ion conductor (15NaI∙LiBH4) as a solid electrolyte. Continuous lithiation/delithiation of the a-Si film was confirmed. At room temperature, the charge-discharge cycles were stable over 80 cycles with the high Coulombic efficiency of 99%. On the other hand, the poor rate performances are the problem; the capacities remained at approximately 1300 mAh/g at 12.7 μA/cm2. Heating the cell at 60 °C resulted in the improvement of the rate performance, which can be due to the improvement of the Li+ conductivity of 15NaI∙LiBH4. In order to understand the correlation between the microstructure and Li+ conductivity of 15NaI∙LiBH4, the as-milled sample was post-annealed and the variation in the microstructure was observed by transmission electron microscopy (TEM). It was indicated that the lattice defects, such as dislocation and lattice distortion, have a significant contribution for the Li+ ion conductivity of the 15NaI∙LiBH4. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchical N-doped carbon nanocages exhibit robust structure for confining LiBH 4. • 50LBH@NC-NbF 5 initiates dehydrogenation at 140.6 °C. • 50LBH@NC-NbF 5 can retain 93% reversible H 2 capacity after 20 cycles. • In-situ formed NbB 2 species is considered the final active and stable nanocatalyst. • N heteroatoms can anchor Nb cations and weaken B-H bonds proved by DFT calculations. A synergetic approach of nanoconfinement coupling with in-situ formed nanocatalysts was developed to fabricate a novel and robust nano-LiBH 4 system. The nanoconfining scaffold exhibits an unparalleled 3D hierarchical architecture featuring micro-, meso-, and macro-pores assembled by 2D interconnected nanosheets that consist of 0D hollow nitrogen-doped carbon nanocages. This structure possesses an accumulated pore width of 7.79 nm, extremely high pore volumes of 3.16 cm3/g, and a theoretical loading capacity of 67.9 wt% for LiBH 4. The in-situ formed NbB 2 species transformed from initial NbF 5 nanoparticles is confirmed as the final active nanocatalyst. It is worth mentioning that the defective N heteroatoms within the scaffold can serve the role of coordinating with Nb cations and weaken the B-H bonds as supported by the DFT calculations. With an optimized loading of 50 wt% LiBH 4 , the initial dehydrogenation temperatures can be reduced to 140.6 °C, and the system can rapidly release 7.55 wt% H 2 at 320 °C within 39 min. Furthermore, the nanoconfined system exhibits excellent low-temperature reversibility, retaining 93 % of its capacity after 20 cycles at 300 °C. This study provides innovative perspectives on the design of novel scaffold structures doped with defective heteroatoms for the nanoconfinement and synergetic catalysis of de/rehydrogenation for metal borohydrides. [ABSTRACT FROM AUTHOR]

All-solid-state Li-S batteries (use of solid electrolyte LiBH4) were prepared using cathodes of a homogeneous mixture of graphene oxide (GO) and reduced graphene oxide (rGO) with sulfur (S) and solid electrolyte lithium borohydride (LiBH4), and their electrochemical performance was reported. The use of LiBH4 and its compatibility with Li metal permits the utilization of Li anode that improves the vitality of composite electrodes. The GO-S and rGO-S nanocomposites with different proportions have been synthesized. Their structural and morphological characterizations were performed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the results are presented. The electrochemical performance was tested by galvanostatic charge-discharge measurements at a 0.1 C-rate. The results presented here demonstrate the successful implementation of GO-S composites in an all-solid-state battery.

Two-dimensional layered material of Ti 3 C 2 has been used to improve the hydrogen desorption properties of LiBH 4. The results of temperature-programmed dehydrogenation (TPD) and isotherm dehydrogenation (TD) demonstrate that adding the Ti 3 C 2 contributes to the hydrogen storage performance of LiBH 4. The dehydrogenation temperature decreases and the dehydrogenation rate increases with increasing the adding amounts of Ti 3 C 2. The onset dehydrogenation temperature of LiBH 4 + 40 wt% Ti 3 C 2 composite is 120 °C and approximately 5.37 wt% hydrogen is liberated within 1 h at 350 °C. Furthermore, the activation energy of LiBH 4 + wt.% Ti 3 C 2 is also greatly reduced to 70.3 kJ/mol, much lower than that of pure LiBH 4. The remarkable dehydrogenation property of the LiBH 4 + 40 wt% Ti 3 C 2 may be due to the layered active Ti-containing Ti 3 C 2 and the high surface area of MXene. • Ti 3 C 2 MXene significantly improve the dehydrogenation of LiBH 4. • Onset dehydrogenation temperature of LiBH 4 is reduced to 120 °C. • 5.37 wt% hydrogen in 40% Ti 3 C 2 composite is liberated within 1 h at 350 °C. • Improved dehydrogenation is due to layered and high surface area of MXene Ti 3 C 2. [ABSTRACT FROM AUTHOR]

The dehydrogenation reaction pathway and rate-limiting step of a nano-LiBH 4 + nano-MgH 2 mixture with a 0.5:1 molar ratio, which has been shown to have the ability to reversibly release and absorb ∼5.7 wt% H 2 at 265 °C, have been investigated in detail. The study reveals that the solid-state dehydrogenation kinetics of the MgH 2 + 0.5 LiBH 4 mixture at 265 °C is nucleation-and-growth controlled. The rate-limiting step for dehydrogenation via the two parallel reaction pathways has been identified through examination of the elementary reactions as the nucleation and growth of reaction products LiH and MgB 2. The interfacial area between MgH 2 and LiBH 4 plays a critical role in the nucleation and growth of LiH and MgB 2 , and thus influence the dehydrogenation kinetics and H 2 storage capacity of the MgH 2 + 0.5 LiBH 4 mixture. X-ray diffraction, SEM analysis and specific surface area measurements reveal that the evolution of the powder characteristics before and after isothermal hydrogen uptake/release cycles is consistent with the kinetics observation and analysis. This study indicates that to further improve the dehydrogenation kinetics of the MgH 2 + LiBH 4 mixture, the nucleation and growth rates of LiH and/or MgB 2 should be enhanced in the future, while the interfacial area between MgH 2 and LiBH 4 should be increased and maintained to be as large as possible during hydrogen uptake/release cycles. Image 1 • The solid-state dehydrogenation kinetics of the MgH 2 + LiBH 4 mixture is nucleation-and-growth controlled. • The rate-limiting step for dehydrogenation is the nucleation and growth of reaction products LiH and MgB 2. • The interfacial area between MgH 2 and LiBH 4 plays a critical role in the nucleation and growth of LiH and MgB 2. • Decay in the reaction kinetics is associated with particle growth and decrease in the interfacial area between reactants. [ABSTRACT FROM AUTHOR]

Abstract Boron sources in forms of SiB 4 /FeB/TiB 2 were used to react with LiF/LiH under hydrogen atmosphere to investigate their effectiveness for synthesizing LiBH 4 , a promising hydrogen storage material. Fourier transform infrared (FTIR) study revealed the formation of B H bond vibrations in these hydrogenated systems, and it demonstrated the generation of LiBH 4. When using FeB and TiB 2 , few amounts of B H bonds were formed in the hydrogenated samples either reacting with LiH or LiF. When utilizing SiB 4 , the formation of B H bonds was promoted for both systems mixing with LiH and LiF. The results imply that a stepwise process of LiBH 4- x →LiBH 4 possibly took place during the hydrogenation process. Importantly, SiB 4 LiH system exhibited the best hydrogenation performance. At moderate conditions of 250 °C and 10 MPa H 2 , LiBH 4 was successfully synthesized from this system. A facile synthesis pathway, SiB 4 (s) + 4LiH(s) + 6H 2 (g) → 4LiBH 4 (s) + Si(s), having a Δ r H m of −65 kJ/mol H 2 , was proposed. This study supports that the chemical state of boron in the reactant is an important factor affecting the generation of LiBH 4. A hydrogenation reaction between SiB 4 and CaH 2 or MgH 2 may be also applicable for synthesizing Ca(BH 4) 2 or Mg(BH 4) 2 , which are regarded as potential hydrogen storage materials. Graphical abstract Alternation of chemical state of B in forms of MB x facilitates the formation of LiBH 4 under moderate conditions. Image Highlights • Tuning chemical state of B could facilitate the formation of LiBH 4. • Formation of B H bonds was confirmed in SiB 4 /FeB/TiB 2 LiH/LiF systems. • Synthesis of LiBH 4 was facilitated in SiB 4 LiH under moderate conditions. • A facile hydrogenation reaction pathway was proposed. [ABSTRACT FROM AUTHOR]

The 0.55LiBH 4 -0.45Mg(BH 4) 2 (LMBH) eutectic composite is promising for solid-state hydrogen storage, as it exhibits a high hydrogen capacity and a very low initial dehydrogenation temperature. However, its main hydrogen release steps still require higher temperatures. In the present study, few-layer Ti 2 C has been synthesized and utilized as catalysts in the LMBH. Compositing LMBH with varying amounts of Ti 2 C (10, 20, 30, and 40 wt%) results in low initial dehydrogenation temperatures (164–110 °C), fast desorption rates and high hydrogen capacities (7.5–10.5 wt%) at a low temperature of 260 °C. The LMBH-30Ti 2 C composite yields 6.5 wt% H 2 even at as low as 200 °C. Additionally, the LMBH-30Ti 2 C composite could reversibly store 3.5 wt% H 2 during the second to fourth dehydrogenation cycles without degradation. The outstanding hydrogen storage performance could be attributed to decomposition driven by reactions between high-valence Ti ions and LMBH, the in-situ formation of the active metal Ti catalyst, and the prevention of aggregation in the Ti 2 C-doped LMBH. • Few-layer Ti 2 C is obtained by etching and ultrasonic exfoliation process. • LMBH-30Ti 2 C desorbs 6.5 wt% and 9.6 wt% H 2 at 200 °C and 260 °C within 5 h. • LMBH-30Ti 2 C reversibly stores 3.5 wt% H 2 at 260 °C without degradation. • The few-layer structure and multi-valent Ti make Ti 2 C a good catalyst for LMBH. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dehydrogenation properties of Bi + S/Se/Te co-doped LiBH 4 are investigated theoretically. • Bi + S/Se/Te co-doping yields a destabilized LiBH 4 with favorable H-desorption. • The decreased B-H interaction and formed Li-S/S/Te bond favor for LiBH 4 destabilization. • Bi + Se addition is more beneficial for LiBH 4 decomposition. A systematic study for the dehydrogenation of LiBH 4 modified with Bi and S/Se/Te was performed by first-principles density functional theory calculations. It is found that Bi-for-Li and S/Se/Te-for-H co-substitution allow lower occupation energy and total energy for Bi + S/Se/Te co-doped LiBH 4 , compared to Bi-for-Li and S/Se/Te-for-B co-substitution. Thus, corresponding compounds Li 7 BiB 8 XH 31 (X = S, M1; X = Se, M2; X = Te, M3), as well as pristine compound Li 8 B 8 H 32 (M0), are selected as representatives for hydrogen desorption energies and electronic structures calculations. Our calculated results show that Bi + S/Se/Te co-doping yields a destabilized LiBH 4 with enhanced dehydrogenation performance, with the atomic and molecular hydrogen desorption energies (E d -H and E d -H 2) and the scaled bond order between B-H (BOs B-H) all decreasing in the order of M0 > M3 > M2 > M1. This destabilization of LiBH 4 using Bi + S/Se/Te is attributed to the decrease of B-H covalent interactions, the formation of Li-S/Se/Te bonds, and the stronger electronegativity of Bi (relative to Li atom) and S/Se atoms (relative to H atom). Bi + S addition can lower the hydrogen desorption energies to −0.511 eV (E d -H) and 1.061 eV (E d -H). However, LiBH 4 with Bi + S additives may generate S-H interactions for H 2 S formation, causing a loss of reversibility for hydrogen storage. For this fact, Bi + Se co-doping should be beneficial for LiBH 4 decomposition. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Li-N-H doped with LiBH 4 can be rapidly heated up by microwave heating. • Li 4 BN 3 H 10 acts as the microwave absorber and catalyst in Li-N-H doped with LiBH 4. • Li-N-H+7.6 wt.%LiBH 4 desorbed completely at 250 °C within 30 min by microwave heating. • The activation energy for Li-N-H+7.6 wt.%LiBH 4 by microwave heating was 43.9 kJ/mol. Abstract Hydrogen desorption properties of Li-N-H system (composed of LiH+LiNH 2) doped with LiBH 4 as catalyst and microwave absorber have been investigated under microwave irradiation. The results showed that pure Li-N-H system can not be heated effectively by microwave irradiation, but it can be rapidly heated up to 500 °C within 5 min with 7.6 wt.% LiBH 4 addition by a microwave heating with a power of 400 W. Further study indicates that it is Li 4 BN 3 H 10 generated during the ball milling process that acts as the microwave absorber and catalyst. Li-N-H+7.6 wt% LiBH 4 by microwave heating desorbed 4.95 wt.% hydrogen which is 3.6 times more than that of Li-N-H +7.6 wt.% graphite by electric resistance heating at 250 °C within 30 min, indicating that the desorption kinetics of Li-N-H system is improved by the combination of the catalytic effect of Li 4 BN 3 H 10 and microwave irradiation. Furthermore, the isothermal kinetics of Li-N-H with 7.6 wt.% LiBH 4 under microwave irradiation were well fitted by Johnson-Mehl-Avrami-Kolmogorov (JMAK) model and the activation energy was 43.9 kJ/mol H 2 which is significantly lower than that under electric resistance heating, demonstrating that the desorption kinetics of Li-N-H with LiBH 4 addition could be effectively improved by microwave irradiation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A comparative study on dehydrogenation of Mg-doped LiBH 4 and Li 2 B 12 H 12 is made. • Mg can modify the dehydrogenation properties of LiBH 4 and Li 2 B 12 H 12. • Mg effect on dehydrogenation performance is more obvious in LiBH 4 than in Li 2 B 12 H 12. • Li 2 B 12 H 12 formation should be suppressed during dehydrogenation of LiBH 4 -MgH 2. Abstract In view of the decomposition of LiBH 4 -MgH 2 involving LiBH 4 -Mg or Li 2 B 12 H 12 -Mg, in the present study, a comparative study on the dehydrogenation performance of Mg-doped LiBH 4 and Li 2 B 12 H 12 (the intermediate compound of individual decomposition of LiBH 4) has been made using first-principles calculations. Our studies aim at providing new insights into the promoting hydrogen storage properties of LiBH 4 -MgH 2. The results show that the properties of LiBH 4 and Li 2 B 12 H 12 can be modified by Mg resulting in favorable H-desorption, due to that Li B/H bond is weakened and Mg B bond is formed as Mg addition. Nevertheless, it is noted that, compared to LiBH 4 systems, (1) Li 2 B 12 H 12 systems with relatively higher hydrogen dissociation energies are disadvantage to hydrogen desorption, due to the stronger B H, Li B and Li H bonds and the suppression of the formation of MgB 2 upon dehydrogenation; (2) Li 2 B 12 H 12 systems with unique B B bonds are unfavorable for hydrogen storage reversibility, since B B bonds is considered to be the main obstacle for rehydrogenation of metal borohydrides. From these, we believed that upon decomposition of LiBH 4 -MgH 2 , suppressing the formation of intermediate compound Li 2 B 12 H 12 should be of great importance for further improvement of hydrogen storage properties of LiBH 4 -MgH 2. [ABSTRACT FROM AUTHOR]

Abstract In this work, LiBH 4 –20 wt% PP composite was prepared by ball-milling with as-synthesized hierarchical pyrolysis polyaniline (PP) and LiBH 4 , and the hydrogen sorption performance as well as catalytic mechanism of the composite was studied. It is found that the onset desorption temperature of the composite decreases to 75 °C, almost 235 °C lower than that of the milled LiBH 4. Moreover, the composite could release 4.1 wt% H 2 and rehydrogenate a total of 4.4 wt% H 2 when the temperature raiseds up to 400 °C, showing an outstanding reversibility, which even 3.9 wt% H 2 can be kept after five cycles. Through scanning electron microscopy (SEM) observation and X-ray diffraction (XRD) analysis, we found that the PP surface forms some nanoholes after hydrogenation-dehydrogenation cycles, which leads to the confinement of some LiBH 4 in the PP nanoporous structure, therefore, the hydrogen sorption kinetics and reversibility are significantly enhanced. In addition, we also found the oxygenic groups of the PP can react with LiBH 4 forming LiBO 2 and Li 3 BO 3 , where the containing Li–B–O bonds loaded in the porous structure of the PP catalyze the hydrogenation reaction of LiBH 4. Graphical abstract The cycling absorption hydrogen curves of the LiBH 4 –20 wt% PP composite with 5 cycles at 400 °C under 5.0 MPa. The illustration is the cycling absorption capacity of the LiBH 4 –20 wt% PP composite within 60 min fx1 Highlights • Hydrogen storage properties of LiBH 4 were enhanced by pyrolysis polyaniline. • Pyrolysis polyaniline lowered the initial desorption temperature of LiBH 4 to 75 °C. • The LiBH 4 /pyrolysis polyaniline composite absorbed 3.9 wt% H 2 within 5 cycles. • The formed Li–B–O complexes catalyzed the decomposition and formation of LiBH 4. [ABSTRACT FROM AUTHOR]

Abstract: Ammonium perchlorate(AP) and LiBH4 can form an oxidation‐fuel energetic system, which provides a new development direction in designing novel mixed explosive formula. The microcalorimetry and self‐designed slow cook‐off setup were used to study thermal performance of AP/LiBH4 energetic powders and grains respectively. Experimental results show that heat release in microcalorimetry method for the mixed system at low temperature was due to the reaction between LiBH4 and residual water vapour. The oxidant gases from AP decomposition participate in the oxidation of LiBH4 at high temperature. The ignition temperature for the AP/LiBH4 grain was 270 °C and the explosion reactions were violent in slow cook‐off test. [ABSTRACT FROM AUTHOR]

A detailed analysis of the dehydrogenation mechanism and reversibility of LiBH4 doped by as-derived Al (denoted Al*) from AlH3 was performed by thermogravimetry (TG), differential scanning calorimetry (DSC), mass spectral analysis (MS), powder X-ray diffraction (XRD), scanning electronic microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results show that the dehydrogenation of LiBH4/Al* is a five-step reaction: (1) LiBH4 + Al → LiH + AlB2 + “Li-Al-B-H„ + B2H6 + H2; (2) the decomposition of “Li-Al-B-H„ compounds liberating H2; (3) 2LiBH4 + Al → 2LiH + AlB2 + 3H2; (4) LiBH4 → LiH + B + 3/2H2; and (5) LiH + Al → LiAl + 1/2H2. Furthermore, the reversibility of the LiBH4/Al* composite is based on the following reaction: LiH + LiAl + AlB2 + 7/2H2 ↔ 2LiBH4 + 2Al. The extent of the dehydrogenation reaction between LiBH4 and Al* greatly depends on the precipitation and growth of reaction products (LiH, AlB2, and LiAl) on the surface of Al*. A passivation shell formed by these products on the Al* is the kinetic barrier to the dehydrogenation of the LiBH4/Al* composite.

In this study, we analyze and compare the physical and electrochemical properties of an all solid-state cell utilizing LiBH4 as the electrolyte and aluminum as the active anode material. The system was characterized by galvanostatic lithiation/delithiation, cyclic voltammetry (CV), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). Constant current cycling demonstrated that the aluminum anode can be reversibly lithiated over multiple cycles utilizing a solid-state electrolyte. An initial capacity of 895 mAh/g was observed and is close to the theoretical capacity of aluminum. Cyclic voltammetry of the cell was consistent with the constant current cycling data and showed that the reversible lithiation/delithiation of aluminum occurs at 0.32 V and 0.38 V (vs. Li+/Li) respectively. XRD of the aluminum anode in the initial and lithiated state clearly showed the formation of a LiAl (1:1) alloy. SEM-EDS was utilized to examine the morphological changes that occur within the electrode during cycling. This work is the first example of reversible lithiation of aluminum in a solid-state cell and further emphasizes the robust nature of the LiBH4 electrolyte. This demonstrates the possibility of utilizing other high capacity anode materials with a LiBH4 based solid electrolyte in all-solid-state batteries. [ABSTRACT FROM AUTHOR]

The electronic structures and energies of neutral and anionic (LiBH4) x clusters ( x = 1 - 5) have been systematically studied by using density functional theory with the B3LYP/6-311++G(d, p) level. For investigating the importance of excess electrons on hydrogen storage capacity, the interactions between hydrogen atoms and the anionic (LiBH4) x clusters are also examined. The calculated formation energies of the anionic clusters show that the anionic clusters have a high thermal stability. It is found that hydrogen atoms are adsorbed on the anionic (LiBH4) x clusters chemically with adsorption energies in the range of −69.13 - −153.73 kcal/mol. The hydrogen storage capacity can be improved from 18.51% to 19.26 - 22.12% in weight percent depending on the size of various anionic (LiBH4) x clusters. Our calculation results show that the existence of excess electrons on the (LiBH4) x clusters can enhance the hydrogen storage capacity. The Mulliken charge analysis was performed to illustrate the interactions between H atoms and the anionic (LiBH4) x clusters. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

For all-solid-state lithium-sulfur batteries, the volume expansion effects of the sulfur cathode would cause the capacity decay, resulting in reducing the efficiency of the cell. In this work, nano-spherical sulfide polyacrylonitrile (NS-SPAN) is prepared with a uniform diameter of around 150 nm. While Li 4 (BH 4) 3 I as solid-state electrolyte effectively inhibits the growth of lithium dendrites and enhances the cycling performance. Then, NS-SPAN as the cathode is matched with Li 4 (BH 4) 3 I solid-state electrolyte to assemble the all-solid-state lithium-sulfur battery. At a current density of 0.2 mAcm−2 at 100 °C, the voltage of the Li–Li cell is able to maintain stable after 250 h cycling. After 150 cycles at 0.1 C, the lithium-sulfur battery still has a discharge capacity of 878.5 mAh g−1, with the coulombic efficiency of 99%. • SPAN plays a significant role in suppressing the shuttle effect and reducing the volume expansion. • Li 4 (BH 4) 3 I effectively inhibits the growth of lithium dendrites and enhances the cycling performance. • The Li-SPAN all-solid-state battery displays excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

The hydrogen desorption/absorption behaviors of LiAlH4/LiBH4 with a focus on the effects of catalysts, namely TiCl3, TiO2, VCl3, and ZrCl4, were investigated using a thermal-volumetric apparatus. The hydrogen desorption was performed from room temperature to 300 °C with a heating rate of 2 °C min−1. The LiAlH4–LiBH4 mixture with a molar ratio of 2:1 decomposed between 100 and 220 °C, and the hydrogen desorption capacity reached up to 6.6 wt %. Doping 1 mol % of a catalyst to the mixture resulted in the two-step decomposition and a decrease in the hydrogen desorption temperature. All the doped samples provided lower amountz of desorbed hydrogen than that obtained from the undoped one. No hydrogen absorption was observed under 8.5 MPa of hydrogen pressure and 300 °C for 6 h. Despite the fact each of the catalysts may affect the hydrogen storage behaviors of the mixture differently, none resulted in a change in the sample reversibility.

In this study, we analyze and compare the physical and electrochemical properties of an all solid-state cell utilizing LiBH4 as the electrolyte and aluminum as the active anode material. The system was characterized by galvanostatic lithiation/delithiation, cyclic voltammetry (CV), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). Constant current cycling demonstrated that the aluminum anode can be reversibly lithiated over multiple cycles utilizing a solid-state electrolyte. An initial capacity of 895 mAh/g was observed and is close to the theoretical capacity of aluminum. Cyclic voltammetry of the cell was consistent with the constant current cycling data and showed that the reversible lithiation/delithiation of aluminum occurs at 0.32 V and 0.38 V (vs. Li+/Li) respectively. XRD of the aluminum anode in the initial and lithiated state clearly showed the formation of a LiAl (1:1) alloy. SEM-EDS was utilized to examine the morphological changes that occur within the electrode during cycling. This work is the first example of reversible lithiation of aluminum in a solid-state cell and further emphasizes the robust nature of the LiBH4 electrolyte. This demonstrates the possibility of utilizing other high capacity anode materials with a LiBH4 based solid electrolyte in all-solid-state batteries.

LiBH4 is considered as a prominent solid state hydrogen storage material with 18.3wt% hydrogen storage capacity, while suffering sluggish dehydrogenation kinetics and poor reversibility. It is hypothesized that nano scale LiBH4 and catalyst mixture will show improved dehydrogenation performance. In this study, LiBH4 and Ni catalyst precursors were well mixed in organic solvent with activated carbon, followed by freeze drying and thermal reduction process. The as-prepared sample showed a nano Ni decorated LiBH4 clusters covered by the thin film of activated carbon, which helped reduce the doping amount of Ni catalyst and improve the reversibility of LiBH4. The onset of LiBH4 decomposition temperature was reduced to 243°C with the first main hydrogen releasing peak at 278°C. The sample desorbs 5.5wt% hydrogen within 1h at 330°C. Although underwent serious degradation, a partial reversibility was observed under 9MPa hydrogen pressure for 3h at 400°C. [ABSTRACT FROM AUTHOR]

2LiBH4/MgH2 system is a representative and promising reactive hydride composite for hydrogen storage. However, the high desorption temperature and sluggish desorption kinetics hamper its practical application. In our present report, we successfully introduce CoNiB nanoparticles as catalysts to improve the dehydrogenation performances of the 2LiBH4/MgH2 composite. The sample with CoNiB additives shows a significant desorption property. Temperature programmed desorption (TPD) measurement demonstrates that the peak decomposition temperatures of MgH2 and LiBH4 are lowered to be 315 °C and 417 °C for the CoNiB-doped 2LiBH4/MgH2. Isothermal dehydrogenation analysis demonstrates that approximately 10.2 wt% hydrogen can be released within 360 min at 400 °C. In addition, this study gives a preliminary evidence for understanding the CoNiB catalytic mechanism of 2LiBH4/MgH2 [ABSTRACT FROM AUTHOR]

Abstract: Using pseudopotential density functional theoretical methods, we systematically study the phase stability, structural properties and high-pressure behaviors of LiBH4. The total-energy calculations show that the orthorhombic structure with Pnma symmetry found by experiments [J. Alloys Compd. 346, 200 (2002)] is more stable than the other proposed structures at 0 K and 0 GPa. The calculated Pnma structural parameters agree well with experimental results. With the pressure extracted directly from first-principles calculations, we predict that the Pnma to Pnma* [Phys. Rev. Lett. 104, 215501 (2010)] and the Pnma* to P-421c structural phase transitions occur at 2.0 and 11.6 GPa respectively, accompanied with volume contractions of 1.02% and 2.78%. It may reduce the volume requirement of hydrogen storage. We find that the Vinet EOS fitting can introduce some errors in predicting structural phase transitions of LiBH4. A detailed study of the electronic structures reveals the bonding characteristics between B and H and between Li and H as well as the nonmetallic features of Pnma, Pnma* and P-421c structures. [Copyright &y& Elsevier]

The dehydrogenation/hydrogenation properties of LiBH4-xMg(OH)2 were systematically investigated. The results show that the LiBH4-0.3Mg(OH)2 composite possesses optimal dehydrogenation properties: approximately 9.6 wt% of hydrogen is released via a stepwise reaction with an onset temperature of 100 °C. In the range of 100–250 °C, a chemical reaction between LiBH4 and Mg(OH)2 first occurs to give rise to the generation of LiMgBO3, MgO and H2. From 250 to 390 °C, the newly developed LiMgBO3 reacts with LiBH4 to form MgO, Li3BO3, LiH, B2O3 and Li2B12H12 with hydrogen release. From 390 to 450 °C, the decomposition of LiBH4 and Li2B12H12 proceeds to release additional hydrogen and to form LiH and B. A further hydrogenation experiment indicates that the dehydrogenated LiBH4-0.3Mg(OH)2 sample can take up 4.7 wt% of hydrogen at 450 °C and 100 bar of hydrogen with good cycling stability, which is superior to the pristine LiBH4. [ABSTRACT FROM AUTHOR]