Hydrogen energy, as a clean and efficient energy carrier, its safe storage is the key. TiFe-based alloys have become a research hotspot due to their advantages such as high theoretical hydrogen storage capacity and low cost. However, their application is limited by drawbacks such as easy surface oxidation, harsh activation conditions and poor cycling stability. Modification strategies of TiFe-based alloys in recent years are reviewed, with a focus on the influences of mechanical alloying, non-stoichiometric design, element substitution and surface treatment on the hydrogen storage performance of TiFe alloys. Future research directions and priorities of TiFe-based alloys are also discussed, providing theoretical guidance for practical applications.

Solid-state hydrogen storage technology is regarded as a key link in the development of the hydrogen energy industry chain due to its excellent volumetric hydrogen storage density and intrinsic safety characteristics. Among numerous hydrogen storage materials, AB₅-type rare earth-based hydrogen storage alloys have become a research hotspot because of their mild activation conditions, efficient hydrogen absorption and desorption under normal temperature and pressure, as well as excellent PCT plateau characteristics and outstanding anti-toxicity performance. However, the basic alloy LaNi₅ cannot be directly applied due to problems such as low hydrogen absorption and desorption plateau pressure, low hydrogen storage capacity, and poor cycle stability. To address the above issues, alloying regulation of AB₅-type hydrogen storage alloys has been widely recognized as an effective solution. This review systematically summarizes the effects of common element substitution on the A- and B- sides on the structural properties of AB₅-type hydrogen storage alloys and their underlying mechanisms, and systematically summarizes the existing problems and future research directions, which can provide theoretical guidance for the optimal design of high-performance AB₅-type hydrogen storage alloys.

With the acceleration of global energy transition, hydrogen energy has received widespread attention due to its high energy density and clean characteristics. Among hydrogen storage technologies, solid-state hydrogen storage is considered the most promising approach because of its high safety and large volumetric energy density. However, solid-state hydrogen storage materials face a dilemma between achieving high hydrogen density and maintaining suitable operating temperatures, a trade-off that severely limits their practical applications. In recent years, data-driven technologies have shown significant potential in material design, performance prediction, and catalyst optimization, providing new avenues for the development of novel hydrogen storage materials. This paper systematically reviews the research progress of data-driven technologies in the field of solid-state hydrogen storage, focusing on three key aspects: First, the construction and application of high-quality databases to provide reliable support for model training; second, forward and inverse design of alloys based on machine learning, achieving efficient prediction and optimization of material properties; and third, the use of multi-agent platforms such as Cat-Advisor for intelligent screening and optimization of magnesium-based dehydrogenation catalysts through multimodal processing of literature information. The article also discusses challenges such as inadequate characterization of catalyst microstructures, limited inverse design capabilities, and difficulties in extracting high-quality data from multiple sources. It envisions the prospects of advancing solid-state hydrogen storage material research and development towards systematization and intelligence through the integration of AI, multimodal intelligent agents, and improvements in database quality.

Metal nitrogen hydride hydrogen storage materials, represented by Li-Mg-N-H, is recognized as one of the most potential solid-state materials for hydrogen storage due to its excellent hydrogen storage capacity, good reversibility of hydrogen absorption/desorption reaction, and ideal thermodynamic properties. However, the core challenges faced by this system are the complexity of its hydrogen absorption and desorption reactions and the high kinetic barriers. In this paper, the main composition and hydrogen storage performance of the system, performance optimization methods including chemical composition adjustment, nanostructure design, catalytic modification and practical applications of the system were systematically reviewed. The catalytic modification focused on the effect and mechanism of alkali metal based compounds, metal borohydride, transition metals and their compounds, rare earth compounds, carbon materials as catalysts. Finally, the key research directions of the system for practical applications are discussed.

Magnesium-based hydrogen storage materials have attracted much attention due to their high hydrogen storage density, abundant Mg resources, relatively low cost and good reversibility. However, their high hydrogen desorption temperature and slow kinetic performance have restricted their practical application. The design of magnesium-based hydrogen storage alloys with high hydrogen storage capacity, excellent kinetic/thermodynamic performance and cyclic stability is of great significance for the safe storage and transportation of hydrogen energy in the future. This paper systematically summarizes the research progress in the preparation of magnesium-based hydrogen storage materials by alloying, focuses on sorting out the action mechanisms of different types of elements and the regulation laws of alloying processes on the microstructure of materials, discusses the challenges and development prospects faced by the alloying strategy, and is expected to point out the direction for the research on magnesium-based solid-state hydrogen storage materials.

The global energy crisis is becoming increasingly severe. Hydrogen, with its advantages of environmental friendliness, abundant resources, and high energy density, has emerged as one of the most promising new energy carriers. Hydrogen storage and transportation serve as the critical link between hydrogen production and utilization, forming a key component of the hydrogen application system. Solid-state hydrogen storage materials, recognized for their large storage capacity, high volumetric density, and excellent safety performance, are considered the most promising solution for hydrogen storage. Among them, hydrogen generation by hydrolysis of solid-state hydrogen storage materials offers a safe and efficient method for releasing hydrogen. With advantages such as high safety and convenience, high energy density and controllable reactivity, as well as diverse chemical reaction mechanisms and material systems, it presents a highly promising technological pathway for hydrogen storage and transportation, making it an ideal choice for on-demand, portable, and online hydrogen supply. This article systematically reviews the research progress and technical principles of hydrogen generation by hydrolysis from solid-state hydrogen storage materials, analyzes the hydrogen storage characteristics and current development status both domestic and international of various hydrolytic hydrogen generation materials, and introduces the application scenarios, challenges, and bottlenecks of this technology. Based on this analysis, the article proposes a focused approach to tackling key issues in four areas:1 material modification and catalytic system optimization;2 innovation in hydrolysis reaction systems and operation modes;3 material system innovation and large-scale production;4 standardization system construction.

Hydrogen storage and transportation challenges severely impede the large-scale utilization of hydrogen energy in daily life and industry. Therefore, the development of safe and efficient new storage and transportation technologies becomes an urgent need in the current field. Among various hydrogen storage techniques, light metal hydrides are favored for their high safety. However, they usually struggle to achieve a favorable balance between kinetics, thermodynamic stability, hydrogen storage capacity and cycling stability. This limitation severely hinders their commercial application. Existing optimization strategies, such as nanoconfinement, alloying, and catalyst addition, have achieved important progresses but fall short of enabling practical application of these materials. In recent years, the introduction of external fields has provided a new method for optimizing the hydrogen storage performance of metal hydrides and demonstrated significant application potential. The traditional modification of light metal hydrides and the influence of external fields on their hydrogen storage properties are comprehensively reviewed, with a particular focus on the effect of light on metal hydrides. The aim is to provide theoretical references and practical directions for further optimization of the hydrogen storage properties of metal hydrides.

As one of the most promising clean energy sources in the 21st century, the storage and transportation technology of hydrogen energy is a key bottleneck restricting its widespread application. Solid-state hydrogen storage technology has attracted widespread attention due to its high safety and potential high energy density, among which hydrogen storage alloy materials are one of the main research directions. The research status and typical applications of low-pressure solid-state hydrogen storage alloys have been reviewed, focusing on the hydrogen storage performances, modification methods and application progress of A_nB_m intermetallic compounds such as AB, AB₂, AB₅, etc., BCC solid solution alloys vanadium-based and titanium-based alloys and magnesium-based alloys. At the same time, further focusing on the contradiction between techno-economics and safety, combined with the current practical application, hydrogen storage alloys can be divided into low-temperature type and high-temperature type according to their working characteristics. The techno-economics of low-temperature alloys A_nB_m alloys and BCC solid solution alloys is facing cost challenges, as the price of AB₅ materials is rather high, The cost of the metal raw materials for equivalent hydrogen storage is higher than 5 000 yuan/kg H₂, and the cost of vanadium-based BCC solid solution alloys is about 4 000 yuan/kg H₂ although ferrovanadium master alloy is introduced. However, its safety advantages are significant. Thanks to the low pressure operating range 0.1-5.0 MPa and good air stability, it is classified as a low-risk system and has been used in hydrogen storage by ships and forklifts. In contrast, high-temperature magnesium-based alloys show the potential of raw material cost in terms of techno-economics the price of magnesium raw materials < 40 000 yuan/t, but the nanosizing and alloying process significantly pushes up the comprehensive cost. Its safety has obvious hidden dangers, due to the inherent flammability of the material ignition point of 473 ℃ and high dehydrogenation temperature requirements 200-300 ℃, and thus is evaluated as a high-risk system. With the overcoming of technical bottlenecks and the improvement of the industrial chain, low-pressure solid-state hydrogen storage alloys are expected to play a greater role in transportation, industry, energy and other fields.

Metal hydrides and lightweight coordinated metal hydrides have become a preferred solution for hydrogen storage owing to their high hydrogen storage density and high security. Nevertheless, the harsh operation temperature for dehydrogenation severely limits their further development and application. Benefitting from the alteration of the dehydrogenation pathway and the reduction in reaction enthalpy, reactive hydride composites RHCs have been shown to significantly enhance the hydrogen desorption thermodynamics in comparison with single hydrogen storage materials. Furthermore, the effective enhancement of both the kinetic and cycling properties can be achieved by the combination of catalytic doping methods. In this paper, a systematic review of recent research progress in the field of RHCs was presented, while the hydrogen desorption mechanism and the research progress on catalytic doping modification of a variety of RHCs were discussed in detail. Finally, the focus and development direction of future research were outlined based on the challenges currently being faced by RHCs.

Hydrogen energy is an effective approach to reduce carbon emissions in the maritime sector and promote the green and sustainable development of marine power. Solid-state hydrogen storage technology, with advantages such as high volumetric hydrogen storage density and good operational safety, provides a highly promising solution to the safe and efficient storage of hydrogen fuel for marine applications. The principles, classifications, and characteristics of solid-state hydrogen storage technology were reviewed. The current application status of this technology in the maritime field was elaborated. The challenges faced by this technology in the application of the shipping industry were analyzed, and the future development trends were also prospected. The aim is to provide certain theoretical reference for promoting the wide application of solid-state hydrogen storage technology in the maritime field.

Hydrogen energy is an ideal energy carrier for the transition from fossil energy to renewable energy. However, due to the flammable and explosive nature of hydrogen, the development of safe and efficient hydrogen storage technologies remains a key challenge in the application of hydrogen energy. Vanadium-based body-centered cubic BCC hydrogen storage alloys have a theoretical hydrogen storage capacity of up to 3.8% at room temperature, significantly higher than traditional AB₅ and AB₂ type hydrogen storage alloys, thus demonstrating great application potential. However, in practical applications, this type of alloy still faces problems such as low reversible hydrogen storage capacity, poor cycle stability, and high raw material costs. This paper systematically reviews the research progress of vanadium-based BCC type hydrogen storage alloys, with a focus on the issue of high cost. It analyzes in detail three strategies for reducing alloy costs and discusses the key challenges faced by each strategy. On this basis, it provides prospects for future research directions, offering a reference for the design and development of high-performance and low cost hydrogen storage alloys.

Metal hydride MH - hydrogen compressors MHHC or thermal sorption compressors MH TSC can convert thermal energy into compressed hydrogen gas. Compared with traditional mechanical hydrogen compression methods, the main advantage is the use of low-grade heat sources instead of electricity. Its benefits include simple design and operation, no moving parts, compact structure and safety and reliability. Metal hydride materials or hydrogen compression materials, as an important component of this type of thermal engine, possess several fundamental characteristics to achieve efficient performance in hydrogen compression. The application scenarios, basic principles and main types and characteristics of metal hydrides as hydrogen compression materials for regulating hydrogen pressure technology are summarized.

Solid-state hydrogen storage based on metal hydrides is considered a highly promising method for hydrogen storage. However, the inherently low thermal conductivity of metal hydride powders severely restricts the reaction efficiency during hydrogen absorption/desorption in metal hydride beds, posing a critical bottleneck for the large-scale application of solid-state hydrogen storage technology. Accurate measurement of the effective thermal conductivity of metal hydride beds, along with targeted strategies for improvement, is of great significance for the optimal design, performance enhancement, and cost control of solid-state hydrogen storage devices. Mainstream measurement methods for the effective thermal conductivity of metal hydride beds are systematically reviewed, and the applicability, advantages, and disadvantages of various testing approaches are compared and analyzed. Technical pathways for enhancing the thermal conductivity of beds, focusing on structural optimization and material compounding, are summarized. Research progress in numerical simulations of heat and mass transfer in one-dimensional, two-dimensional, and three-dimensional metal hydride beds is reviewed, and the scope of application and accuracy differences among various models are analyzed. The relevant research findings can provide theoretical support and technical reference for the optimized design of heat and mass transfer structures in solid-state hydrogen storage devices.

The capacity degradation of super-lattice rare earth-Mg-Ni-based alloys is ascribed to decomposition of [A₂B₄] subunits and mismatch between [A₂B₄] and [AB₅] subunits. To achieve a stable super-lattice structure, Sm-Mg-Ni based AB₂-type alloys with similar structures to the [A₂B₄] subunit were prepared. XRD patterns reveal that the alloys maintain a stable MgCu₄Sn structure after hydrogen absorption and desorption cycles. Based on stable [A₂B₄] subunits, super-lattice Sm-Mg-Ni-based Sm_0.55Mg_0.25Y_0.20Ni_2.95Al_0.15 hydrogen storage alloy was prepared. The alloy consists of PuNi₃ phase and Ce₂Ni₇ phase. The hydrogen storage capacity at 298 K is 1.53%mass fraction. When the temperature reaches 323 K, the maximum hydrogen absorption capacity can be reached within 60 s. After 20 cycles of hydrogen absorption and desorption, the supe-lattice structure remains unchanged and the capacity retention rate can reach 96.3%.

Ti-V hydrogen storage alloys exhibit significant application potential in the fields of hydrogen energy storage, transportation and power generation due to their high hydrogen storage capacity and favorable kinetic properties. Firstly, the hydrogen storage mechanism of Ti-V solid solution alloys, the positions occupied by H atoms in hydrogen storage alloys, and the changes in the crystal structure of solid solution hydrogen storage alloys during hydrogen absorption and desorption are elucidated. Secondly, the effects of various preparation methods arc melting, vacuum induction melting, powder metallurgy and ball milling on the microstructure and hydrogen storage performance of Ti-V solid solution hydrogen storage alloys are systematically summarized. Thirdly, the modification of Ti-V hydrogen storage alloys by different elements is investigated, and the effects and characteristics of different elements on the substituting of Ti and V atoms in the alloy are studied. Finally, the application prospects of Ti-V hydrogen storage alloys is prospected.

Offshore wind power-to-hydrogen is a crucial approach for developing marine renewable energy, and hydrogen storage technology serves as the key to realizing energy transfer. Focusing on offshore scenarios, the feasibility of applying solid-state hydrogen storage technology has been investigated. A system model of "offshore wind power-electrolytic hydrogen production-solid-state hydrogen storage-maritime transportation to shore" is constructed, with MgH₂ as the hydrogen storage medium, to analyze the impacts of parameters such as electrolyzer configuration ratio and hydrogen storage capacity on system performance. The results show that the ratio of electrolyzers to wind power directly affects system energy efficiency, requiring a trade-off between power consumption and equipment utilization. Increasing hydrogen storage capacity can reduce hydrogen curtailment rate, but the marginal benefit diminishes. The economic viability of the system is constrained by multiple factors, necessitating a comprehensive consideration of energy efficiency and costs. This research provides a theoretical basis for the selection of hydrogen storage technologies in offshore wind power-to-hydrogen systems.

Mg-based solid state hydrogen storage material has been considered as one of the efficient hydrogen sto-rage carriers in virtue of its high hydrogen sorption capacity, abundant deposit and low cost. Unfortunately, the high thermodynamics stability 74.7 kJ/mol and sluggish hydrogen storage kinetics impede seriously its commercial application. Despite the traditional approaches including alloying, elemental catalyzing and solid solution, etc. A large amount of research has confirmed the fact that the dual-modifications upon the thermodynamics/kinetics of Mg-based material via nanoengineering in nanoscale can be successfully achieved and consequently, the significant enhancement of hydrogen storage performance further accelerates its industrial application in future. In this paper, the basic logic of nanoengineering has been clarified and the synthesis of nanomaterial and nanoconfinement technology in recent years are also systematically summarized and reviewed from the perspective of preparative technique and dimension. Meanwhile,the structure-function relationship between microstructure,catalyzing effects and the optimal hydrogen storage performances has been summarized. Eventually, the review makes a comment about the merit/demerit and probable application and development direction of nanoengineering for incoming hydrogen storage industry. Further, the reference and inspiration for the design and development of a new generation of high-performance magne-sium-based solid-state hydrogen storage materials via nanoengineering is highly expected in this review.

Hydrogen storage alloy as an anode material has an important influence on the performance of Ni-MH secondary batteries. To further improve the cycling stability of hydrogen storage alloy electrode materials with RE-Mg-Ni system superlattice structure, Mg-free A₅B₁₉ Gd_1-xSm_xNi_3.33Mn_0.17Co_0.2Al_0.1 0≤x≤1 alloy was designed and investigated. The effects of the substitution of Gd by the rare-earth Sm element on the alloy′s annealing microstructure, hydrogen storage in the gas, and electrochemical properties were systematically investigated. The results show that after annealing at 1 273 K, the alloy microstructure consists of 2H-Ce₂Ni₇-type main phase and 3R-Ce₅Co₁₉-type dual phase. With the increase of Sm content x, the abundance of 2H-Ce₂Ni₇-type main phase increases, and the 3R-Ce₅Co₁₉-type phase gradually decreases. Meanwhile, the cellular parameters a, c, V of the 2H-Ce₂Ni₇-type phase and the 3R-Ce₅Co₁₉-type phase all increase gradually with increasing Sm content. The effect of rare earth Sm on the gas hydrogenation behavior of the alloys is more pronounced. After the addition of Sm, the alloys exhibit a certain tendency of hydrogen-induced amorphization during hydrogen absorption and desorption. With the increase of Sm content, the maximum hydrogen absorption capacity of the alloys gradually increases, and the PCT curve platform for hydrogen storage and the enthalpy of formation of alloy hydrides of ΔH^Θ are significantly reduced. The electrodes of the alloys containing Sm exhibit good charge/discharge activation properties. With the increase of Sm content, the discharge capacity of the electrodes increases from 279.6 mAh/g to 378.4 mAh/g at x=1.0. After 100 charge/discharge cycles, the alloy electrodes maintain good capacity retention S100 = 94.3%-98.8%, with a slight decrease in capacity retention rate as Sm content increases. When Sm content x > 0, the alloy electrodes exhibit good high-current discharge performance, with HRD₉₀₀ values ranging from 84.7% to 87.6%, respectively. The x = 1.0 alloy combines a high discharge capacity 378.4 mAh/g, good cycling stability S100=94.3%, and high-rate discharge performance HRD₉₀₀ = 84.7%, demonstrating excellent overall electrochemical properties.

Metal-based solid-state hydrogen storage technology is one of the critical pathways to address hydrogen storage and transportation challenges. Among these materials, magnesium-based materials have attracted significant attention due to their high hydrogen storage capacity 7.6%, low cost, and favorable reversibility. However, the high dehydrogenation temperature and sluggish kinetics remain unresolved. The mechanisms of rare earth elements and their compounds in enhancing the hydrogen absorption and desorption performance of magnesium-based hydrogen storage materials are focused on, with a systematic review of the research progress in rare earth element alloying and catalytic modification of rare earth materials. Studies demonstrate that rare earth alloying significantly reduces thermodynamic barriers through lattice reconstruction and the optimization of hydrogen diffusion channels, enabling Mg-RE alloys to complete dehydrogenation within 10 min. Rare earth catalysts lower the initial dehydrogenation temperature of MgH₂ to below 220 ℃ via interfacial electron transfer and multiphase synergistic effects. Nevertheless, challenges such as reliance on rare earth resources and unclear phase transition mechanisms in composite systems persist as bottlenecks for large-scale applications. Future research should integrate material design with green preparation processes to advance magnesium-based hydrogen storage materials toward high-density, low-energy consumption, and long-cycle life development, thereby facilitating the scaling-up of the hydrogen energy industry.

Efficient and safe storage and transportation of hydrogen is a crucial step in realizing the utilization of hydrogen energy. Magnesium-based hydrogen storage materials are regarded as one of the promising media for hydrogen storage and transportation due to their high hydrogen storage density, excellent cycling performance, and abundant resources. However, their practical application is hindered by strong thermodynamic stability, slow reaction kinetics, and stringent technical requirements for hydrogen storage systems. In recent years, rare earth elements or rare earth compounds have been successfully introduced into magnesium-based hydrogen storage materials through various strategies, significantly improving the hydrogen absorption and release performance of the materials. The research progress of rare earth in magnesium-based hydrogen storage materials in recent years is systematically summarized. The roles of rare earth in the design, preparation technology, alloying, structural characteristics, as well as additives or catalysts of magnesium-based hydrogen storage materials are focused on. Future research directions are also looked forward to.

To enhance hydrogen absorption/desorption kinetics while reducing Mg-H bond stability without compromising storage capacity, rare earth elements of La and Y, transition metal Ni, and In were incorporated into the Mg-based alloy. The In-containing alloy was subjected to melt spinning to produce an amorphous-nanocrystalline structure. Crystallization annealing at 400 ℃ for 4 h was performed to enhance the hydrogen storage properties. The phase transformations and structural evolution of Mg₉₀La₂Y₂Ni₆ and Mg₉₀La₂Y₂Ni_4.8In_1.2 alloys were systematically characterized before and after hydrogenation. The results revealed that melt spinning yielded a predominantly amorphous structure with nanocrystalline domains in the Mg₉₀La₂Y₂Ni_4.8In_1.2 alloy. The as-cast Mg₉₀La₂Y₂Ni₆and Mg₉₀La₂Y₂Ni_4.8In_1.2, annealed Mg₉₀La₂Y₂Ni_4.8In_1.2alloys consisted of Mg, Mg₂Ni, La₂Mg₁₇, and YNi₃ phases. In doping resulted in the formation of MgIn and Mg₂NiIn solid solutions within the Mg and Mg₂Ni matrices, respectively. Notably, In incorporation induced lattice contraction in Mg while expanding the Mg₂Ni lattice parameters. Crystallization annealing facilitated complete crystallization, achieving homogeneous element distribution and microstructure refinement. The newly generated grains and grain boundaries established additional pathways for hydrogen diffusion. Kinetic measurements demonstrated that the annealed Mg₉₀La₂Y₂Ni_4.8In_1.2 alloy exhibited optimal hydrogen storage capacity at 260-320 ℃, and can completely dehydrogenation within 500 s at 320 ℃ and within 1 500 s at 260 ℃, with a significantly reduced activation energy of 63.36 kJ/mol.

To address the insufficient cycling stability of La-Ni based superlattice hydrogen storage alloys, a series of La_1-xY_xNi_3.75Mn_0.2Al_0.15x=0,0.2,0.4,0.6,0.8,1.0 alloys were prepared by arc melting followed by annealing at 1 273 K for 24 h. The influence of A-site Y substitution on structural evolution and electrochemical properties was systematically investigated. Rietveld refinement of XRD data revealed phase transitions and anisotropic lattice contraction induced by varying Y content. Electrochemical characterization, including galvanostatic charge-discharge, cycling tests, pressure-composition-temperature PCT measurements, exchange current density analysis, and kinetic evaluations, clarified the role of Y in regulating discharge capacity, cycling stability, and high-rate dischargeability. The results demonstrate that moderate Y substitution x=0.6 optimizes the unit cell volume and hydrogen diffusion channels, suppresses hydrogen-induced amorphization and corrosion, and significantly enhances the discharge capacity 390.7 mAh/g, capacity retention S₁₀₀=85.8%, and kinetic performance. In contrast, excessive Y incorporation leads to structural deterioration and severe capacity fading. This study systematically elucidates the structural regulation effect of Y in La-Ni based superlattice alloys and its profound influence on hydrogen storage performance, providing theoretical insights and experimental guidance for the design of advanced Ni-MH battery anode materials.

The reaction of MgH₂ with water to produce a large amount of hydrogen is conducive to the development of hydrogen energy in the field of fuel cells, but its slow hydrogen production rate and the key problem of the dense layer of MgOH₂ limit its application. In this paper, multiple hydrolysis experiments were conducted using sea salt solutions with concentrations of 0.3 mol/L, 0.9 mol/L, 1.7 mol/L, and 2.5 mol/L, respectively, together with 0.1 g of MgH₂. Hydrolysis kinetics curves were measured at different temperatures. The resulting hydrolyzed products underwent analysis of phase and morphology using XRD and SEM scanning techniques, and the hydrolysis mechanism was examined. The influence of sea salt solutions of different concentrations on the particle surface were analyzed. The hydrolysis kinetics process and activation energy were analyzed by linear fitting using the Avrami-Erofeev and Arrhenius equations. In the study, it was found that the hydrolysis performance and surface activity were improved the best when the sea salt solution with a concentration of 0.9 mol/L reacting with 0.1 gMgH₂.At high temperatures, the hydrolysis activation energies of 0.3 mol/L, 0.9 mol/L, 1.7 mol/L, and 2.5 mol/L sea salt solutions were determined to be 33.1±0.4, 26.1±0.5, 36.3±0.8, and 40.1±0.2 kJ/mol, respectively, and the fastest hydrolysis hydrogen evolution rates were 11.33, 12, 10.66, and 11.33 mL/g·s, confirming the effect of concentration on hydrolysis kinetics. These remarkable hydrolysis properties of MgH₂ are significant for the study of magnesium-based alloy hydrides.

Ionic liquids IL as electrolyte solutions possess a wide electrochemical stability window and excellent safety performance, However, the high viscosity and low conductivity of IL solutions pose certain challenges when they are applied in electrochemical devices. In order to effectively enhance the electrical conductivity of ionic liquids and to explore their application in proton-type batteries, an aqueous ionic liquid solution [EMIM][Ac]+x H₂O was used as the electrolyte. Through testing and analysis, the structural and physicochemical properties changes of the aqueous [EMIM][Ac]+xH₂O ionic liquid solution were studied. The amorphous a-Si thin film negative electrode, sintered NiOH₂ positive electrode, and the aforementioned aqueous ionic liquid solution were used as the electrolyte to assemble a battery. The influence of the aqueous ionic liquid solution on the electrochemical perfor-mance of the battery and the negative electrode of the a-Si thin film was investigated. The research results show that when the volume fraction x of water is greater than or equal to 30%, a hydrogen bond network structure dominated by H₂O molecules gradually forms in the aqueous ionic liquid solution. This is conducive to the rapid conduction of protons through the Grotthuss mechanism. As the water content increases, the viscosity of [EMIM][Ac]+x H₂O volume fraction solution significantly decreases, the conductivity gradually increases, the wettability between the solution and the silicon film electrode gradually enhances, and at the same time, the electrochemical window of the solution gradually decreases from 3.53 V to 2.24 V. When water is added to the [EMIM][Ac] ionic liquid, it can significantly enhance the performance of the battery. When the volume fraction of water x is 30%, the charge transfer impedance Rct of the a-Si thin film material is the smallest. At this time, the discharge capacity of the corresponding battery reaches the maximum value of 1 700.82 mAh/g. After 100 charge-discharge cycles, the capacity retention rate S100 of the battery is 93%. When the volume fraction of water x is between 30% and 40%, the high-rate discharge performance HRD1000 of the battery is 87.03% to 94.80%, demonstrating excellent high-current discharge performance. This research provides a new idea for the development of high-energy-density proton-type batteries.

This study prepared annealed La_0.6Y_0.4Ni_3.75Al_0.15Mn_0.1 superlattice hydrogen storage alloys using a vacuum arc melting furnace and a vacuum tube annealing furnace. The alloys were treated with a 10 mol/L NaOH solution at 90 ℃ to investigate the effect of alkali treatment on the surface structure,properties,and electrochemical performance of the hydrogen storage alloys. XRD results indicated that the untreated alloy consisted of polytypic phases including CaCu₅,2H-Pr₅Co₁₉,and 3R-Ce₅Co₁₉,and the phase structure remained unchanged after alkali treatment. SEM observations revealed that the surface morphology of the alloy transformed from an initially rough and uneven state to a smooth and flat characteristic. EDS and XPS analysis showed that a Ni-rich layer and NiOH₂ formed on the alloy surface,which can act as a catalytic layer to accelerate the hydrogen electrode reaction. The dissolution and precipitation of Al and Mn elements in the alkali environment promoted Ni enrichment,thereby enhancing the corrosion resistance of the alloy and facilitating hydrogen adsorption. As the alkali treatment time increased,the activation performance, maximum discharge capacity,and other related electrochemical properties of the alloy electrode first increased and then decreased. When the treatment time was 3 h,the maximum discharge capacity of the alloy electrode increased from 313.1 mAh/g untreated to 368.9 mAh/g,and the high-rate discharge performance HRD₁₂₀₀ improved from 33.88% to 67.97%. The exchange current density and hydrogen diffusion coefficient exhibited the same trend. The alkali treatment altered the surface state of the hydrogen storage alloy, provided more active sites, optimized the contact between the electrode and the electrolyte,reduced polarization impedance,enhanced electrochemical activity and stability,and accelerated the kinetics of the hydrogen electrode reaction.

Lightweight high-entropy alloys of Mg₄₅Ti₁₅Al₂₇Co₆Ag₇, Mg₄₀Ti₂₀Al₂₇Co₆Ag₇, and Mg₃₀Ti₃₀Al₂₇Co₆Ag₇ were prepared by high-energy ball milling. The effects of different Mg/Ti ratios on the alloy microstructure and hydrogen storage performance were analyzed using scanning electron microscopy SEM, X-ray diffraction XRD, transmission electron microscopy TEM, and gas-phase hydrogen absorption and desorption experiments. The results show that the Mg₄₅Ti₁₅Al₂₇Co₆Ag₇, Mg₄₀Ti₂₀Al₂₇Co₆Ag₇ and Mg₃₀Ti₃₀Al₂₇Co₆Ag₇ alloys are composed of FCC phases, HCP phases and a small amount of Co-rich phases. Reducing the Mg/Ti ratio from 3∶1 to 2∶1 slightly promotes an increase in the FCC phase content, thereby enhancing the hydrogen storage capacity of the alloy. However, reducing the Mg/Ti ratio from 3∶1 to 1∶1 slightly increases the FCC phase content but causes the HCP phase to transform into a stable, non-hydrogen-absorbing Al₉Co₂ phase after hydrogen absorption and desorption. The FCC phase in the alloy exhibits stronger hydrogen absorption and desorption capabilities. Since the Co-rich phase and Al₉Co₂ phase cannot absorb hydrogen, but the Al₉Co₂ phase facilitates the hydrogen desorption process, the Mg/Ti ratio of 1∶1 significantly reduces the hydrogen absorption capacity of the alloy while increasing the hydrogen desorption rate.

La_0.6Y_0.4Ni_3.75Al_0.15Mn_0.2 superlattice hydrogen storage alloys were prepared using a vacuum arc melting furnace. The alloys were subjected to annealing treatments at temperatures ranging from 900 ℃ to 1 050 ℃ under a 0.2 MPa Ar atmosphere for 10 h. The effects of annealing temperature on the alloy′s structure and properties were studied using X-ray diffraction and electrochemical testing methods. The results show that at 900 ℃, the alloy consisted of A₅B₁₉-type Pr₅Co₁₉ and Ce₅Co₁₉ phases, and AB₅-type CaCu₅ phase. When the temperature was increased to 950 ℃, the phase abundance (mass fraction) of CaCu₅ decreased from 5% to 2.5%, while the phase abundance of Ce₅Co₁₉ and Pr₅Co₁₉ increased from 57.6% and 37.5% to 58.1% and 39.4%, respectively. At this temperature, the A₅B₁₉-type phase reached its maximum phase abundance, comprising 97.5% (mass fraction). When the temperature was increased to 1 000 ℃, the phase abundance of CaCu₅ increased to 11% (mass fraction). At 1 050 ℃, excessive loss of Mn resulted in the formation of A₂B₇-type Ce₂Ni₇ phase. The alloy exhibited optimal electrochemical properties at an annealing temperature of 950 ℃, where the A₅B₁₉ phase content peaked. The maximum discharge capacity was 318.5 mA·h/g, and after 100 cycles, the capacity retention (S₁₀₀) was 72.5%. The high-rate discharge performance (HRD₁₂₀₀) at a current density of 1 200 mA/g was 77.6%. Therefore, the adjustment of phase abundance through annealing treatment significantly improved the comprehensive electrochemical performance of La-Y-Ni-based alloys.

AB₅-type lanthanum-nickel hydrogen storage alloy is highly promising for engineering applications due to its rapid hydrogen absorption and desorption rates at room temperature. However, large-scale hydrogen production processes, such as fossil fuel reforming and biomass gasification, often introduce impurity gases which can impair the performance of hydrogen storage alloys. To impact of common impurity gases found in hydrogen sources, namely O₂, CO₂, H₂S, N₂, CO, H₂O, CH₄, Ar, and He, on the hydrogen storage characteristics of AB₅-type LaNi₅ alloys has been investigated. First-principles calculations and pressure-composition-temperature PCT experimental tests were employed to explore the poisoning mechanisms of these impurities on the alloy′s performance, evaluates the adsorption strengths of the impurity gases, and examine the microscopic changes in the electronic structure of the hydrogen storage alloys during poisoning. The results indicate that, compared to hydrogen, O₂, CO₂, H₂S, N₂, and CO are preferentially adsorbed onto the material′s surface. Among these gases, O₂, H₂S, and CO exhibit larger relative adsorption energy values of 2.57 eV, 1.91 eV and 1.21 eV, respectively. Oxygen O₂ and hydrogen sulfide H₂S undergo dissociative adsorption on the LaNi₅ surface. O₂ dissociates into O atoms, which adsorb onto the hydrogen absorption active sites. H₂S dissociates into SH and H species, which then stably adsorb at the active sites. The remaining gases are adsorbed on the LaNi₅ surface in their molecular forms. The effect of impurity gases on the hydrogen storage performance of the alloy was also verified by PCT experimental tests, which showed that CO and O₂ deteriorated the hydrogen storage performance of LaNi₅ more seriously, with a decrease of 40% and 10%, respectively.

A series of heterogeneous Gyroid structures with axially graded porosity were designed based on conical surface equations and fabricated using selective laser melting (SLM). Quasi-static compression tests and finite element simulations were conducted to systematically investigate the effects of porosity gradient and loading direction on the mechanical properties and energy absorption characteristics of the porous structures. The results indicate that Gyroid axial gradient porous structures exhibit anisotropic mechanical behavior. When loaded perpendicular to the gradient direction, the structures demonstrated a strengthening effect, attributed to stress concentration in low-porosity regions. In contrast, loading parallel to the gradient direction led to strength degradation, resulting from progressive collapse initiated in high-porosity regions. The extent of strengthening or weakening was positively correlated with the gradient range. The energy absorption efficiency of Gyroid axial gradient porous structures was generally lower than that of their homogeneous counterparts, primarily due to incompatible deformation at porosity gradient interfaces, which impeded stress transfer. The structure with a 70%-30% porosity gradient loaded perpendicular to the gradient direction exhibited the best overall mechanical and energy absorption performance, with a yield strength of 92.1 MPa and a plateau stress of 163.1 MPa, representing increases of 15.86% and 10.42%, respectively, compared to the homogeneous structure. Its maximum energy absorption reached (63.06±0.53) MJ/m³, comparable to that of the homogeneous structure (63.97 MJ/m³).

As a key piece of ground equipment widely used in China's water injection oil production technology, the safe and stable operation of the plunger water injection pump directly impacts the production efficiency, oil quality, and overall output of oilfields. The plunger rod and combination valve in the plunger water injection pump are critical, vulnerable, and corrosive components, and their proper functioning is essential to the water injection and oil recovery process. This study focuses on the failed plunger rod and combination valve from the water injection station of the Xingzichuan Oil Production Plant in the Yanchang Oilfield. The causes of failure were systematically analyzed using various methods, including material analysis, metallographic structure observation, and microhardness testing. The microscopic morphology of the corrosion scale on the surface of the failed components was observed using a scanning electron microscope (SEM), and the phase composition of the corrosion scale was further analyzed using X-ray diffraction (XRD) technology. The results reveal that the base material of the failed plunger rod is 27SiMn steel, with a metallographic structure consisting of cementite and ferrite, while the material of the failed combination valve is 2Cr13 stainless steel, primarily exhibiting martensite. SEM analysis showed significant cracking and peeling of the coating on the plunger rod surface, with noticeable corrosion pits in localized areas, while the combination valve exhibited numerous small pitting pits and honeycomb-like corrosion areas. XRD analysis identified that the corrosion scale on the surface of the failed components is primarily composed of CaCO₃ and FeOOH, which contributed to the failure of the water injection pump components. The findings of this research provide a theoretical foundation for addressing the corrosion issues in water injection pump components within water injection oil production systems and offer technical recommendations for improving the corrosion resistance of these components. By further optimizing related technologies, the service life of components can be extended, enhancing the safety and stability of oilfield water injection and oil production systems, and offering critical support for oilfield production.

Waste amorphous Fe-Si-B flake powders were compacted into magnetic powder cores, and the microstructural evolution and magnetic properties of the internal particles were investigated by changing the heat treatment temperature. The results show that α-FeSi and Fe₂B nanocrystalline phases began to precipitate at a heat treatment temperature of 380 ℃, which is lower than the crystallization exothermic temperature measured by thermal analysis. At 420 ℃, an average grain size of the magnetic powder cores was 13.62 nm, approaching the exchange interaction length (15-20 nm), but partial agglomeration occurred between grains. Additionally, the grain sizes of the precipitated α-FeSi and Fe₂B phases were comparable, with the volume fraction of Fe₂B phase being significantly lower than that of the α-FeSi phase. Increasing the heat treatment temperature led to rapid grain growth of both α-FeSi and Fe₂B phases, resulting in an increased average magnetic anisotropy constant, and degradation of overall magnetic performance. The magnetic powder cores treated at 420 ℃ exhibited relatively superior AC magnetic properties, with an effective permeability of 64.5, total losses of 251.9 mW/cm³ (10 mT, 1 MHz), and a DC bias characteristic of 60.0% (at 8 000 A/m). These experimental results provide critical insights for the modification and recycling of waste amorphous Fe-Si-B materials.

In order to improve the mechanical properties such as hardness, tensile strength, and elongation of ferrosilicon alloy materials, the influence of casting cooling rate on the mechanical properties of ferrosilicon alloy was studied. After preparing ferrosilicon alloy samples using silica, coke, and iron oxide scales and casting them, three cooling methods of natural cooling, air cooling, and water cooling were implemented, with corresponding cooling rates of 0.5, 12.7, and 660.0 ℃/min, respectively. Test the mechanical properties such as compression characteristics, tensile characteristics, and microhardness of the cooled alloy sample. The results showed that with the increase of casting cooling rate, the tensile strength, elongation and hardness of ferrosilicon alloy were significantly improved. In the compression performance test, the sample cooled by water at 660.0 ℃/min exhibited higher stress values and better compressive performance. At the same time, friction and wear performance tests showed that the sample cooled by water had the smallest weight loss and the best wear resistance. In the hardness test under high temperature environment, the sample cooled by water has the smallest decrease in hardness and better thermal stability performance. Water cooling has shown significant advantages in improving the mechanical properties, wear resistance, and high-temperature stability of ferrosilicon alloys. It is recommended to prioritize the use of rapid cooling technology in practical production.

Based on micromagnetics theory,magnetic behavior of Ce_1.66Mg_1.34Co₉/α″-Fe₁₆N₂ nano composite bilayer film using the three-dimensional simulation tool OOMMF was systematically investigated. The effects of the hard magnetic phase thickness (L^h) and the soft magnetic phase thickness (L^s) on remanence (M_r), coercivity (H_c), and the maximum energy product ((BH)_max) were intensively studied, while also analyzing the energy variation during the magnetization reversal process. Under a fixed soft magnetic phase thickness L^s,it was found that with the increase in hard magnetic phase thickness L^h, both M_r and (BH)_max gradually decreased,whereas H_c remained relatively unchanged. The optimum (BH)_max was achieved when L^h was 10 nm. Conversely,under a fixed L^h,increasing the L^s led to a gradual increase in M_r,a decrease in H_c,and a gradual increase followed by a decrease in (BH)_max. The optimum (BH)_max occurred when L^s was 10 nm,corresponding to an enhancement of 987.60% compared to single-phase materials. Furthermore,a detailed analysis of the magnetic moment distribution revealed the process of magnetization reversal,from the saturated state to the reverse saturated state,providing a microscopic explanation of the magnetization process in the bilayer film system. By rationally optimizing the thickness combination of the hard and soft magnetic phases, the maximum energy product of the nano composite bilayer film can be significantly improved,resulting in superior comprehensive magnetic performance.

Adiabatic demagnetization refrigeration based on the magnetocaloric effect of magnetic materials is an important method for achieving sub-Kelvin temperatures. The combination of Gd³⁺ with light anion ligands facilitates an increased rare-earth/ligand ratio in magnetocaloric materials, leading to a significant magnetocaloric effect. To explore novel high-performance magnetocaloric materials, LiGdO₂ compound with a high rare-earth/ligand ratio was synthesized via high-temperature solid-state reactions and its magnetocaloric effects were investigated at low temperatures. From the thermomagnetic curves, an antiferromagnetic phase transition is observed in LiGdO₂ around 2.5 K, and strong antiferromagnetic interactions are determined by Curie-Weiss fitting. At 1.8 K, a high saturation magnetization of 166.5 A·m²/kg is recorded for LiGdO₂. When measured at 3.5 K under a magnetic field change of 7 T, a large magnetic entropy change of 30.3 J/(kg·K) is demonstrated by LiGdO₂. These results indicate that LiGdO₂ compound with high rare-earth/ligand ratios is highly competitive among magnetocaloric materials.

To analyze the stress distribution and deformation characteristics of high-strength bolts (HSBs) under lateral vibration loads, in order to evaluate their durability in complex stress environments, the research involves the establishment of mechanical models, simulation settings, and simulation verification for bolted connections. Through finite element simulation technology, the systematic simulations of bolt compression and random vibration loads are carried out, revealing the influence of preload force on stress redistribution in the contact area and deformation of the threaded structure. The research has shown that when the preload force is increased from 20 kN to 80 kN, the maximum stress amplitude at the bolt drilling site under compression conditions decreases by 21.4%, effectively suppressing local plastic deformation. Under the action of random vibration load, there is a 3-fold stress concentration phenomenon in the transition zone of the thread, and the risk of microcrack initiation in this area is significantly increased compared to other parts. This method quantifies the correlation characteristics between deformation and fracture, elucidates the progressive failure mechanism induced by slip at the threaded contact interface, and provides a key theoretical basis for the safe design and life prediction of bolted connections in engineering structures.

Amorphous silicon (a-Si), particularly hydrogenated amorphous silicon (a-Si:H), exhibits ultra-high electrochemical discharge capacity in ionic liquid electrolytes. However, conventional hydrogenation treatments typically require high temperatures, and the hydrogen content in the resulting films is limited. To investigate the relative contribution of heat treatment to the electrochemical performance of modified thin film electrodes, radio frequency magnetron sputtering was used to prepare a-Si thin films with similar thickness. These films were heat-treated at 200 ℃, 300 ℃, and 500 ℃ under high vacuum conditions for 2 h. The results showed that although the heat-treated films maintained an amorphous structure, they exhibited a trend toward crystallization. This structural transition reduced defect density and enhanced structural order. The electrochemical activity, discharge capacity, rate performance, and cycling stability of the thin film electrodes were significantly improved. Specifically, after heat treatment at 200 ℃, the maximum discharge capacity increased by 15.2%, and the capacity retention after 100 cycles improved from 74.8% (before treatment) to 81.4%. After heat treatment at 300 ℃ and 500 ℃, the discharge capacities increased by 54.4% and 59.2%, respectively, and the capacity remained stable after 100 cycles with no degradation. Vacuum heat treatment significantly optimized the performance of a-Si thin film electrodes by improving their structure, demonstrating promising potential for widespread application in energy storage systems such as nickel-metal hydride batteries.

A spectrophotometric method based on F-La-C₁₉H₁₅NO₈ was established to study the fluorine content in rare earth concentrates. Firstly, the sample was decomposed by perchloric acid, and fluorine was separated and enriched by steam distillation. Secondly, phenolphthalein was used to adjust the distillate to neutrality. Thirdly, alizarin aminocarboxylic complex hydrazone was used as a color reagent, acetone was used as a stabilizer, and water bath insulation color development. Finally, the absorbance of the solution was measured at a wavelength of 625 nm. At the same time,the optimal distillation conditions, amounts of color reagent and acetone, water bath temperature, color development time, absorption wavelength, and other conditions were determined. The precision and result comparison experiment showed that the relative standard deviation (RSD) was 2.26%-9.776% (number of measurements n=11),and the absolute error was -0.032%-0.183% which compared to the fluoride ion selective electrode experiment. The recovery experiment showed that the recovery was 96.00%-103.20%. This method is applicable for the determination of fluoride content ranging from 0.10%-2.00% (mass fraction) in rare earth concentrates.

To clarify the impact of post-weld heat treatment (PWHT) on strength and toughness of 1 600 MPa ultra-high-strength steel (UHSS) welded joints, quenching and tempering heat treatment was performed on tungsten inert gas(TIG)-welded joints. Microstructure of the joints was observed and characterized using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Tensile and impact tests were also carried out. Results indicate that the toughness of UHSS weld is reduced due to significant segregation of elements such as Cr, Mo, W, and Si. Quenching and tempering heat treatment can significantly reduce the degree of element in weld metal and transforms weld microstructure from martensite to tempered martensite, thereby improving weld toughness. Mechanical performance tests also reveal that hardness distribution of joints becames more uniform after heat treatment, with tensile strength of base metal and weld increasing to 1 744 MPa and 1 740 MPa, respectively. These findings provide theoretical basis and technical support for welding application of ultra-high-strength steel.

To enhance the performance of iron-rich cobalt-based coatings, three different compositions of coatings were fabricated on the surface of 45 steel by plasma cladding technology, including iron-rich cobalt-based alloy coatings (FeCo), iron-rich cobalt-based alloy composite coatings containing TiC (FeCo-TiC), and iron-rich cobalt-based alloy composite coatings containing TiC-W-Mo (FeCoWMo-TiC). Through comparative analysis of the microstructure, hardness and friction and wear properties of these three coatings, it was found that the microstructure of the FeCo coating is mainly composed of dendritic crystals and equiaxed crystals, and its phase composition is primarily γ-Co and CoC_x. The phase composition of the FeCo-TiC and FeCoWMo-TiC coatings consist of TiC, α(Fe,Co), M₂₃C₆ and M₇C₃ phases. The introduction of W and Mo elements helps to reduce the size of TiC particles in iron-rich cobalt-based alloy coatings. The iron-rich cobalt-based alloy coating TiC-W-Mo has the best hardness and friction and wear properties, followed by the iron-rich cobalt-based alloy coating TiC, while the iron-rich cobalt-based alloy coating has the lowest. The wear mechanisms of the three coatings are mainly abrasive wear and adhesive wear.

H13 steel has a high alloy content, and improper production process control or incorrect alloy usage can lead to elevated titanium (Ti) levels in the molten steel. When the Ti mass fraction exceeds 0.003%, Ti-rich liquid carbides or TiN inclusions may form, severely affecting the fatigue performance and service life of molds. Therefore, this production process achieves stable high-quality H13 steel ingot production by optimizing the chemical composition of H13 steel and strictly controlling the production process. The smelting process requires the use of alloys and materials with low phosphorus (P) and titanium (Ti) content during converter steelmaking and LF refining. Three slag-making operations are performed during converter production, with the first and second furnace slags completely removed. Before blowing, residual steel and slag in the converter hood and ladle must be cleaned thoroughly, and slag carryover during tapping must be strictly controlled. In the early stage of LF refining, chromium (Cr) content is adjusted to ensure a total LF slag volume of at least 30 kg/t, while maintaining low slag basicity of R. The LF slag composition ranges are: w(CaO)=50%-53%,w(Al₂O₃)=24%-28%,w(SiO₂)=13%-15%,w(MgO)=6%-8%,w(TFe+MnO)≤0.5%,R=3.5-4.0. LF refining time is 130-150 min. Before ingot casting, the mold temperature must be maintained between 50-80 ℃. During ingot body pouring, the casting speed is controlled at 0.4-0.5 t/min. After the ingot body is completed, the casting speed is reduced. For pouring the ingot head, the casting speed is controlled at 0.2-0.3 t/min. During the ingot casting process, argon sealing must be ensured while maintaining a steady rise in the molten steel level within the mold. Through these processes, the P mass fraction in H13 steel ingots is kept below 0.012%, and the Ti mass fraction is maintained at no more than 0.002 0%, effectively controlling the quantity and size of liquid carbides and TiN inclusions. The resulting microstructure exhibits excellent high-magnification and low-magnification features, with an impact energy of at least 300 J.