Hydrogen Storage Characteristics Research Articles

The effect of CuI–PbI2 nanocomposite fabricated by the sonochemical route on electrochemical hydrogen storage characteristics

Hydrogen storage is an essential technique for developing hydrogen technology and electrochemical cells in stable energy, transport, and portable power. Hydrogen holds the maximum specific power of all fuels; nevertheless, its low ambient temperature density occurs in a lower energy density; therefore, there is a need to develop advanced storage procedures that own the potential for greater energy density. Therefore, this research incorporates the fabrication of novel nanocomposite (CuI–PbI2) by the sonochemical method, architectural, morphological observations, and relevant electrochemical hydrogen storage features. The electrochemical features with different morphology have revealed 515 and 585 mAh/g discharge capacity for bulk and nano-sized samples after 15 cycles, respectively.

Effect of Cooling Rate below Ms Temperature on Hydrogen Embrittlement of TRIP-Aided Martensitic Steels

Low alloy TRIP steel is expected to be applied to automobile bodies because of its high strength, high ductility, and excellent impact properties and press formability. It has been reported that the low alloy TRIP steel of hydrogen embrittlement resistance is improved by utilizing the hydrogen storage characteristics of highly stable retained austenite. Therefore, for the purpose of increasing the volume fraction of retained austenite, it was produced at various cooling rates below the martensite transformation start temperature. As a result, the volume fraction of retained austenite increased, and then the effect of hydrogen embrittlement decreased. The matrix phase and retained austenite is refined with decrees of the cooling rate. It is considered that the size and surface area of the retained austenite also affected the improvement of hydrogen embrittlement resistance.

A Review of Seasonal Hydrogen Storage Multi-Energy Systems Based on Temporal and Spatial Characteristics

The temporal and spatial characteristics of seasonal hydrogen storage will play a very important role in the coupling of multi-energy systems. This essay believes that there are several key issues worth noting in the seasonal hydrogen storage coupled multi-energy system, namely, hydrogen storage methods, coupling models, and benefit evaluation. Through research, this article innovatively divides seasonal hydrogen storage into two types: space transfer hydrogen storage technology and time transfer physical property conversion hydrogen storage technology. Then sort out the two most typical seasonal hydrogen storage multi-energy system application scenarios and their hydrogen storage unit models. Finally, it is shown that hydrogen storage methods should be selected according to different periods of time and regions, and the benefits should be evaluated before they can be used in practice. This review study is applicable to the process of coupling seasonal hydrogen storage in multi-energy systems. Hydrogen energy is used as an intermediate energy link for the selection, evaluation and modeling of the optimal selection and rational utilization.

Improvement of the hydrogen storage characteristics of MgH2 with a flake Ni nano-catalyst composite.

Magnesium hydride (MgH2) is considered to be one of the most promising hydrogen storage materials owing to its safety profile, low cost and high hydrogen storage capacity. However, its slow kinetic performance and thermal stability limit the possibility of practical applications. Herein, it is confirmed that the hydrogen storage performance of MgH2 can be effectively improved via doping with a flake Ni nano-catalyst. According to experimental results, a MgH2 + 5 wt% Ni composite begins to dehydrogenate at almost 180 °C and could dehydrogenate 6.7 wt% within 3 min at 300 °C. After complete dehydrogenation, hydrogen can be absorbed below 50 °C, and 4.6 wt% H2 can be absorbed at 125 °C within 20 min at a hydrogen pressure of 3 MPa. In addition, the activation energies of MgH2 hydrogen absorption and dehydrogenation decreased by 28.03 and 71 kJ mol-1, respectively. Cycling stability testing showed that the hydrogen storage capacity decreases significantly in the first few cycles and decreases slightly after 10 cycles. Furthermore, it was found that Mg2Ni/Mg2NiH4 was formed initially during the hydrogen absorption or desorption reaction on the surface of Mg/MgH2, which acted as a "hydrogen pump", accelerating the rates of hydrogen absorption and desorption.

Cross-sectional TEM investigation of Mg-LaNi5-Soot hybrids for hydrogen storage

Accumulatively roll bonded (ARB) Mg-LaNi5-Soot hybrid has emerged as a promising hydrogen storage material with enhanced hydrogen storage characteristics, which is amenable to scaled-up production. The key to understanding the hydrogen storage behaviour lies in the nanoscale structure of the hybrid and the associated mechanisms. The focus of the current study is on the use of cross-sectional transmission electron microscopy (TEM) to unravel the underlying mechanisms of hydrogen storage, in the Mg-LaNi5-Soot hybrid. The role of processing variables (ARB passes and strain) and the concomitant evolution of the microstructure (distribution of second phase particles (LaNi5 and soot)) are studied, keeping in view the diffusion of hydrogen and the nucleation of the hydride phase. It is established that the interface between Mg and second phase (LaNi5 and soot) plays a dominant role in the nucleation of the MgH2 phase. The MgH2 nucleation mechanism is studied under the ambit of the Johnson-Mehl-Avrami kinetic (JMAK) model. It is concluded that the internal interfaces provides sites for the nucleation of magnesium hydride.

Effect of hysteresis band control strategy on energy efficiency and durability of solar-hydrogen storage based microgrid in partial cloudy condition

Varying solar radiation during the partial cloudy condition may lead to the frequent switch ON/OFF events of the electrolyzer and fuel cell components in microgrid. The transient operation can ultimately lead to early degradation of these components leading to additional replacement costs. Present work is focused on the analysis of various operating modes on the operational characteristics of hydrogen storage based microgrid system during partial cloudy condition. Different operating modes for the electrolyzer and fuel cell are defined such as rated, variable power and hysteresis band control (HBC) for comparative study of system performance. Present study proposes a strategy in which the FC is operated at maximum efficiency power based on HBC. It was found that proposed HBC strategy significantly reduces the number of switch ON/OFF events of the fuel cell system and operational cost ≈ by 25% and 40%, respectively in microgrid as compared to conventional HBC.

Enhanced thermodynamic properties of ZrNiH3 by substitution with transition metals (V, Ti, Fe, Mn and Cr)

First-principles calculations based on Plane-Wave Self-Consistent Field (PWSCF) method, implemented in quantum espresso program, have been performed on ZrNiH3 substituted with transition metals (V, Ti, Fe, Mn, and Cr). The study aims to investigate the heat of formation in terms of material stability and desorption temperature. It is found that the substitution by transition metals, results in a significant enhancement in the thermodynamic properties accompanied by an increase of the volumetric and gravimetric hydrogen storage capacities. In addition, the obtained values of heat of formation and desorption temperature corroborate with that required by the U.S. Department of Energy (DOE) for stability and volumetric capacity criteria. Moreover, Mn and Fe elements are found to present the lowest substituting content (34%) to obtain optimum hydrogen storage characteristics (enthalpy of formation of - 40 kJ/mol.H2, decomposition temperature of 300 K and volumetric capacity of 134 g.H2/l), without affecting the electronic structure and the metallic character of ZrNiH3.

The influence of refractory metals on the hydrogen storage characteristics of FeTi-based alloys prepared by suspended droplet alloying

The influence of the addition of refractory metals (molybdenum and tantalum) on the hydrogenation properties of FeTi intermetallic phase-based alloys was investigated. The suspended droplet alloying technique was applied to fabricate FeTiTa-based and FeTiMo-based alloys. The phase composition and hydrogen storage properties of the samples were investigated. The samples modified with the refractory metals exhibited lower plateau pressures and lower hydrogen storage capacities than those of the FeTi reference sample due to solid solution formation. It was observed that the equilibrium pressures decreased with the amount of molybdenum, which is in good agreement with the increase in the cell parameters of the TiFe phase. Suspended droplet alloying was found to be a practical method to fabricate alloys with refractory metal additions; however, it is appropriate for screening samples with desired chemical and phase compositions rather than for manufacturing purposes.

Hydrogen storage of a mechanically milled carbon material fabricated by plasma chemical vapor deposition

Carbon materials were prepared by plasma chemical vapor deposition at different pressures without catalyst, and the structure and hydrogen storage characteristics of milled and unmilled samples of the materials were evaluated. Using this approach, we were able to fabricate graphite microcrystals with a crystallite size of several nanometers, and the crystallite size and surface area could be controlled by changing the pressure during plasma chemical vapor deposition. The hydrogen storage capacity of the unmilled materials was 0.3 wt%, but milling increased this value to 1.0 wt% by reducing the crystallite size and increasing the crystallite surface area.

Structure and electrochemical hydrogen storage characteristics of nanocrystalline and amorphous MgNi-type alloy synthesized by mechanical milling

Both element substitution and surface modification were utilized to enhance the electrochemical performances of Mg–Ni-based alloys. Nanocrystalline and amorphous Mg1−xCexNi0.9Al0.1 (x = 0–0.08) + 50 wt.% Ni hydrogen storage alloys were synthesized through mechanical milling. The sample alloys show excellent activation property and have good electrochemical hydrogenation and dehydrogenation property at normal temperature. The discharge capacity has a peak value with Ce content varying which is 461.6 mAh/g for 10-h milled alloy, while that of Ce0.04 alloy augments from 352.6 to 536.9 mAh/g with milling time extending from 5 to 30 h. Cycle stability is conspicuously improved with Ce content and milling duration augment. To be specific, when cycle number is fixed at 100, the capacity retention rate augments from 41% to 72% after Ce dosage rising from 0 to 0.08 for the 10-h milled alloy and from 58% to 76% after milling duration extending from 5 to 30 h for Ce0.06 alloy. Additionally, the electrochemical kinetics of the alloys own peak values with Ce proportion varying; however, they always rise with milling duration extending.

Hydrogen storage performances, kinetics and microstructure of Ti1.02Cr1.0Fe0.7-xMn0.3Alx alloy by Al substituting for Fe

For achieving good economic and environmental benefit, capacity of hydrogen storage alloys plays an important role in high-pressure-metal-hydride system of refueling station. Hydrogen storage characteristics of Ti1.02Cr1.0Fe0.7-xMn0.3Alx (0 ≤ x ≤ 0.1) alloys with main C14 structure were analyzed by Pressure-Composition-Temperature, XRD, HRTEM, SEM, EDS, ICP and XPS measurements, which were prepared by plasma arc melting and subsequent heat treatment. When Al content is lower than 0.05, it can improve the hydrogen reversible storage capacity from 1.58 to 1.65 wt% at 233 K. The pulverization resistances are enhanced by addition of Al (Al content: 0.05, 0.1), and the ductile fractures appear on the particle surfaces. Based on kinetic analysis, the dehydrogenation rates are fast with low activation energies between 7.4 and 9.9 kJ/mol. The mechanism for Al effecting the capacity is that, the big size effect dominates the capacity increase as Al content less than 0.05. Otherwise, higher Al2O3 content covering on the particles surface deteriorate hydrogen storage capacity as Al content exceeding 0.05. Among them, Ti1.02Cr1.0Fe0.68Mn0.3Al0.02 alloy has the best comprehensive properties for high-pressure metal hydride system in hydrogen refueling station. How to utilize the alloy to assemble the compressor and measure the toxicity resistance to impurity gas in H2 may be the future work.

Investigation of Hydrogen Storage Characteristics of MgH2 Based Materials with Addition of Ni and Activated Carbon

Magnesium-based materials are promising as hydrogen storage media due to their high theoretical hydrogen absorption capacity, abundance and low price. The subject of this study are the hydrogen sorption characteristics of the composites 80 wt % MgH2-15 wt % Ni-5 wt % activated carbon (synthesized from polyolefin wax, a waste product of polyethylene production at low pressure which will be denoted further in the text as POW) and 90 wt % MgH2-5 wt % Ni-5 wt % POW, prepared by ball milling under argon atmosphere. Structure, phase and surface composition of the samples before and after hydrogenation are determined by XRD and TEM. The maximum absorption capacity value of the composites at a temperature 573 K and after 60 min. of hydrogenation are 5.3 wt % H2 for the material with higher Ni content and 5.5 wt % H2 for the other sample. The presence of both additives—nickel and activated carbon derived from POW—has a positive impact on hydrogenation kinetics and the capacity achieved. The results from TEM characterization, e.g., the polycrystalline SAED (selected area electron diffraction) show the presence of graphite, Mg and monoclinic Mg2NiH4.

Synthesis of La2MgNi9 hydrogen storage alloy in molten salt

La2MgNi9 alloy is synthesized directly from the sintered mixture of La2O3 + NiO + MgO in the molten CaCl2 electrolyte by the electro-deoxidation method at 740 °C and the electrochemical hydrogen storage characteristics of the synthesized alloy are observed. Sintering (at 1200 °C for 2 h) converts the hygroscopic La2O3 (by the reaction with NiO) into the non-hygroscopic La2NiO4 and La3Ni2O7 phases. The X-ray diffraction peaks indicate that the electro-deoxidation causes LaOCl, Ni, LaNi5 and even target phase La2MgNi9 to form within 2 h process time. The molten salt synthesis process ends up with the final alloy structure of 79% La2MgNi9 and 21% retained LaNi5. The porous alloy structure (with approximately 31.66 m2g−1 specific surface area) is beneficial for higher hydrogen storage capacity and it is observed that La2MgNi9 alloy has promising discharge capacity which is approximately 280 mAhg−1. This work clearly indicates that the electro-deoxidation is a very effective method in the synthesis of the hydrogen storage materials.

Hydrogen storage characteristics of Li and Na decorated 2D boron phosphide

Thermodynamics and electronic investigations of Li/Na-functionalized BP monolayer reveals that it may operate as an attractive basis material for hydrogen storage applications.

Hydrogen storage properties and cycling degradation of single-phase La0.60R0.15Mg0·25Ni3.45 alloys with A2B7-type superlattice structure

Single-phase La–Mg–Ni-based alloys show promising hydrogen storage performance. In this paper, we report the gaseous hydrogen storage characteristics, especially cycling performance of a series of A2B7-type single-phase La0.60R0.15Mg0·25Ni3.45 (R = Pr, Nd and Gd) alloys. These alloys are composed of [AB5] and [A2B4] subunits stacking along c-axis in the ratio of 2:1. With cycling, degradation occurs which results in a sloped and increased plateau pressure, larger hysteresis and decreased hydrogen storage capacity. Structurally, the degradation is caused by the alloys’ lattice expansion/contraction which leads to significant microstrain and decrease in grain size. It is found that the alloy with R = Gd experiences minimal microstrain and preserves good crystallinity during hydrogen absorption/desorption owing to its almost equal [A2B4] and [AB5] subunit volumes. The R = Gd alloy achieved a cycling retention of 89.5% after 100 cycles compared with 79.8%–81.8% for the other two alloys. Additionally, the R = Gd alloy also possesses high reversibility, flat plateau and small hysteresis, showing a great potential in the hydrogen storage applications.

Functionalized graphene materials for hydrogen storage

With growing demands of energy and enormous consumption of fossil fuels, the world is in dire need of a clean and renewable source of energy. Hydrogen (H2) is the best alternative, owing to its high calorific value (144 MJ/kg) and exceptional mass-energy density. Being an energy carrier rather than an energy source, it has an edge over other alternate sources of energy like solar energy, wind energy, and tidal energy, which require a constant energy source dependent upon weather conditions. However, its utilization as an energy carrier has not yet been commercialized due to its poor storage performance, which is attributed to low gravimetric and volumetric densities of adsorbed hydrogen at ambient temperature and technological limitations in meeting the stringent parameters set by Department of Energy, USA. With exceptionally large surface area (2630 m2/g), porous nature, lightweight, and high chemical and thermal stability (melting point ~ 4510 K) along with the possibility of economical and scalable production, graphene-based solid-state porous materials have shown promising applications in efficient hydrogen storage. In this context, the present review discusses the recent advances and progress on the utilization of functionalized graphene, graphene oxide, and its derivatives for effective storage of hydrogen, along with important theoretical advancements via DFT calculations, first-principle calculations, and Monte Carlo Simulations, etc. Pristine graphene has poor hydrogen storage characteristics, and addition of dopants like boron and nitrogen or decoration by transition metals significantly improves the performance. In addition, graphene allows the tuning of surface curvature which can help in achieving a reversible hydrogen storage system with fast kinetics. The impact of external stimuli like electric field and strain on electronic structure of graphene is discussed with the applicability in achieving a highly controllable adsorption–desorption system. Finally, the review concludes with life cycle assessment of graphene-engineered composites for effective hydrogen storage applications, along with their energy and environmental implications.

The activation and hydrogen storage characteristics of the cup-stacked carbon nanotubes

In this study, the cup-stacked carbon nanotubes (CSCNTs) are chemically modified and used for the hydrogen storage for the first time. The SEM and TEM analyses indicate that because they are formed by the stacking of the truncated conical graphene layers the inner- and outer-edges of which are completely exposed, during KOH activation the catalyst particles at the tips of them can be removed completely. The graphene layers of them are exfoliated seriously to form plenty of microcavities. Moreover, many nanosized straight caves and through-holes are formed in the walls of them. As a result, the micropore volume of them increases twelve times and the maximum hydrogen adsorption capacity of them reaches over ten times that of the pristine CSCNTs. These increases exceed the reported data for the conventional coaxial CNTs activated by the same method. Our findings indicate that due to the special graphene layer stacking mode, the micropore structure of CSCNTs can be improved more significantly than the conventional CNTs during KOH activation. They may be a kind of promising carbon nanotube for hydrogen storage.

First-principle investigation for the hydrogen storage properties of NaXH3 (X= Mn, Fe, Co) perovskite type hydrides

In the present study, NaXH3 (X = Mn, Fe, Co) perovskite type hydrides have been investigated by performing first-principles calculation. The results of the structural optimizations show that all these compounds have negative formation energy implying the thermodynamic stability and synthesisability. The mechanical stability of these compounds has been studied with the elastic constants. Moreover, the polycrystalline properties like bulk modulus, Poisson's ratio, etc. have been obtained using calculated elastic constants of interest compounds. The electronic properties have been studied and band structures have been drawn with the corresponding partial density of states. These plots indicated that NaXH3 hydrides show metallic characteristics. The charge transfer characteristics in these compounds have been studied with the Bader partial charge analysis. The phonon dispersion curves and corresponding density of states indicated that NaXH3 compounds are dynamically stable compounds. The investigation on hydrogen storage characteristics of NaXH3 compounds resulted in hydrogen storage capacities of 3.74, 3.70 and 3.57 wt% for X = Mn, Fe and Co, respectively. The present study is the first investigation of NaXH3 perovskite type hydrides as known up to date and may provide remarkable contribution to the future researches in hydrogen storage applications.

Effects of volatilization of lithium on hydrogen storage characteristics of Mg–Ni–Li alloy

Abstract

Enhanced low temperature hydrogen desorption properties and mechanism of Mg(BH4)2 composited with 2D MXene

Mg(BH4)2 occupies a large hydrogen storage capacity of 14.7 wt%, and has been widely recognized to be one of the potential candidates for hydrogen storage. In this work, 2D MXene Ti3C2 was introduced into Mg(BH4)2 by a facile ball-milling method in order to improve its dehydrogenation properties. After milling with Ti3C2, Mg(BH4)2–Ti3C2 composites exhibit a novel “layered cake” structure. Mg(BH4)2 with greatly reduced particle sizes are found to disperse uniformly on Ti3C2 layered structure. The initial dehydrogenation temperature of Mg(BH4)2 has been decreased to 124.6 °C with Ti3C2 additive and the hydrogen liberation process can be fully accomplished below 400 °C. Besides, more than 10.8 wt% H2 is able to be liberated from Mg(BH4)2–40Ti3C2 composite at 330 °C within 15 min, while pristine Mg(BH4)2 merely releases 5.3 wt% hydrogen. Moreover, the improved dehydrogenation kinetics can be retained during the subsequent second and third cycles. Detailed investigations reveal that not only Ti3C2 keeps Mg(BH4)2 particles from aggregation during de/rehydrogenation, but also the metallic Ti formed in-situ serves as the active sites to catalyze the decomposition of Mg(BH4)2 by destabilizing the B–H covalent bonds. This synergistic effect of size reduction and catalysis actually contributes to the greatly advanced hydrogen storage characteristics of Mg(BH4)2.