Storage Of Hydrogen Isotopes Research Articles

Unraveling the substitution and strain-induced hydrogen diffusion performance of ZrCo-based intermetallics

The intermetallic compound zirconium-cobalt (ZrCo) is one of promising alternative materials used in the industry of hydrogen isotope storage. Nevertheless, the deterioration of absorption/desorption kinetics induced by hydrogen-induced disproportionation severely impedes its large-scale promotion. This work concentrates on studying the hydrogen diffusion behavior of ZrCo hydrides due to element substitution combined with triaxial strain (−3% ∼ 3 %) under the framework of the first-principles study. The results indicate that the formation of small-volume hydrogen vacancies is facilitated by Ti substitution as well as compressive strain. Moreover, hydrogen diffusion barrier is reduced after the Ti substitution, leading to a significant increase in diffusion rate. When the Ti content reaches 15 %, it is more conductive to improving the dehydrogenation kinetics of hydride. As the compressive strain increases, the diffusion barrier is reduced to a minimum at −3%. In addition, the Ti substitution and strain play a synergistic effect for enhancing hydrogen diffusion rate. Also, it is found that the performance of hydrogen diffusion and dehydrogenation kinetics is attributed to lattice stability associated with the density of states at the Fermi level. This work provides a new insight to improve dehydrogenation kinetics of ZrCoH3 by taking into account element substitution and external strain.

Hydrogen storage performance of LaNi3.95Al0.75Co0.3 alloy with different preparation methods

Rare-earth AB5-type La–Ni–Al hydrogen storage alloys are widely studied due to their extensive application potentials in hydrogen isotope storage, hydrogen isotope isolation and hydrogen compressors, etc. Good hydriding/dehydriding kinetics, easily activation, high reversibility are important factors for their practical application. However, their overall hydrogen storage performance, especially plateau pressure and hydrogen absorption/desorption durability need to be further optimized. In this study, the microstructures and the hydrogen storage properties of as-cast, annealed, and melt-spun LaNi3.95Al0.75Co0.3 alloys were investigated. The experimental results of XRD and SEM showed that all alloys contained a pure CaCu5 type hexagonal structure LaNi4Al phase. The cell volume increased in an order of annealed ​> ​melt-spun ​> ​as-cast, resulting in a lower hydrogen absorption/desorption plateau pressure and a more stable hydride phase. The hydrogen storage capacity of three alloys was almost the same. The slope factor of the annealed and melt-spun alloys is smaller than the as-cast alloy, indicating that heat-treatment process can make the alloys more uniform. For the cycle stability of the alloys, the hydrogen absorption rate of the annealed alloy and melt-spun alloy was much faster than that of the as-cast alloy after 500 cycles. The melt-spun alloy showed high pulverization resistance during hydrogen absorption/desorption, and exhibited an excellent cycling retention of 99% after 500 cycles, suggesting that melt-spinning process can enhance the cycle stability and improve the cycle life of the alloy.

Achieving excellent cycle stability in Zr–Nb–Co–Ni based hydrogen isotope storage alloys by controllable phase transformation reaction

Hydrogen isotope (deuterium and tritium) as a special form of hydrogen energy, its storage in an efficient and safe way has been paid more and more attention by researchers in recent years. ZrCo alloy is regarding as the one and only promising material for large-scale storage of hydrogen isotope. However, poor cycle life and inferior capacity retention restrict its engineering application. Herein, we propose a co-substitution strategy of Nb (for Zr) and Ni (for Co) in ZrCo alloy to overcome the defects. Significantly, Zr0.8Nb0.2Co0.8Ni0.2 alloy exhibits ultralong cycle life (97.6% retention) and remarkable capacity (2.42 H (f. u.)) in 100 cycles, which far exceeds all existing hydrogen isotope storage alloys (Pd, U and other ZrCo-based alloys). These outstanding performances are entirely revealed from two aspects: stable homogeneous structural phase transformation process of parent structure (Zr0.8Nb0.2Co0.8Ni0.2H0.3-B33 ↔ Zr0.8Nb0.2Co0.8Ni0.2H2.8-B33″) and ordered migration mechanism of H atom (layered and linear de-/intercalation). Our attractive insights into the ultralong cycle life of ZrCo-based alloys through homogeneous structural phase transformation will serve as a pioneer on cycle optimization in the field of hydrogen storage materials.

Regulating local chemistry in ZrCo-based orthorhombic hydrides via increasing atomic interference for ultra-stable hydrogen isotopes storage

Developing a universal and reliable strategy for the modulation of composition and structure of energy storage materials with stable cycling performance is vital for hydrogen and its isotopes storage advanced system, yet still challenging. Herein, an ultra-stable lattice structure is designed and verified to increase atomic chaos and interference for effectively inhibiting disproportionation reaction and improving cycling stability in ZrCo-based hydrogen isotopes storage alloy. After screening in terms of configuration entropy calculation, we construct Zr1−xNbxCo1−2xCuxNix (x = 0.15, 0.2, 0.25) alloys with increased atomic chaos, and successfully achieve stable isostructural de-/hydrogenation during 100 cycles, whose cycling capacity retentions are above 99%, much higher than 22.4% of pristine ZrCo alloy. Both theoretical analysis and experimental evidences indicate the high thermo-stability of orthorhombic lattice in Zr0.8Nb0.2Co0.6Cu0.2Ni0.2 alloy. Notably, the increased atomic chaos and interference in Zr0.8Nb0.2Co0.6Cu0.2Ni0.2 alloy causes regulation in hydrogen local chemical neighborhood, thereby confusing the hydrogen release order, which effectively eliminates lattice distortion and unlocks an ultra-stable lattice structure. This study provides a new and comprehensive inspiration for hydrogen atoms transport behaviors and intrinsic reason of stable orthorhombic transformation, which can contribute to paving the way for other energy storage materials modulation.

Honeycomb ZrCo Intermetallic for High Performance Hydrogen and Hydrogen Isotope Storage

Honeycomb ZrCo Intermetallic for High Performance Hydrogen and Hydrogen Isotope Storage

Synthesis, Characterization, and Hydrogen Isotope Storage Properties of Zr1-x Ti x Co and Zr1-x Hf x Co Alloys (x = 0.1, 0.2)

In the present study, the effect of Hf and Ti substitution of Zr in the ZrCo alloy, used for hydrogen isotope storage, has been investigated in order to ascertain the improvement of the anti-disproportionation property of ZrCo hydrides. The ultimate goal of the investigation is to develop a safe and economically viable solution for the long-term storage of deuterium and tritium. The intermetallic compounds Zrl-xTixCo and Zrl-xHfxCo (x = 0.1, 0.2) were prepared and their suitability for hydrogen isotope storage, protium (H) and deuterium (D), was investigated. The alloys were synthesized by arc melting under a controlled argon atmosphere and characterized by scanning electron microscope and X-ray diffraction analysis. The hydrogen isotope storage behavior of these alloys was probed by loading and unloading protium and deuterium. We present the pressure, composition, and temperature measurements for desorption, together with the thermodynamic parameters (enthalpy and entropy) of these alloys. The experimental results show that Ti and Hf substitution in the ZrCo alloys is suitable for fast delivery of hydrogen isotopes, even after their long-term storage.

In situ transmission electron microscopy studies of 30 keV H2+ and He+ dual-beam irradiated Pd: defect generation and microstructural evolution under varied temperatures and foil thicknesses

To fully understand the tritium aging behavior of palladium (Pd), an important material applied in hydrogen isotope storage and tritium engineering, an in situ irradiation of 30 keV H2+ and He+ dual beam was performed for the investigation of the microstructural evolution in Pd. The irradiation dose, temperature, and sample thickness obviously affected the morphology, distribution characteristics, density, and size of dislocation loops, bubbles, and bubble-loop complexes. Highly dense loops were aggregating at lowered temperatures, whereas the loop density dropped dramatically, producing bubble-loop complexes at elevated temperatures. Most of loops were 1/3<111> Frank loops with quasi-circular under a low dose at 573 K and then transformed to 1/2<110> perfect loops with wavy and polygonal shape at a high dose. The difference in growth behavior between faulted and perfect loops suggested that there was a critical transform loop size ~32 nm in diameter. The heterogeneity in size and shape of bubbles could be attributed to the interaction between bubbles and the periphery loop. Moreover, the hydrogen resulted in the formation of larger bubbles when compared with the single-beam helium irradiation. The unfaulting transition of loops led to bubble redistribution. The corresponding mechanisms of in situ irradiation experimental results were discussed.

Positive impacts of tuning lattice on cyclic performance in ZrCo-based hydrogen isotope storage alloys

ZrCo alloy is considered a promising hydrogen isotope storage material used in nuclear fusion reactors, but its large-scale promotion is inhibited by its poor cycling stability induced by disproportionation. To enhance the cycling stability of ZrCo-H systems, tuning lattice by Pd substitution for Co is performed in this work. The prepared ZrCo0.6Pd0.4 alloy mainly consists of the CrB-type orthorhombic phase (B33), sharing an identical lattice structure with its hydrided phase (ZrCoH3); thus, stable homogeneous structural dehydrogenation/hydrogenation reaction is constructed for the first time with remarkably low lattice fluctuation and dehydrogenation activation energy, in favor of restraining disproportionation. Hence, a highest capacity of 1.45 wt% and optimum capacity retention of 96.67% after 50 dehydriding/hydriding cycles is achieved in ZrCo-H systems. Our work proposes the great potential of tuning lattice for improving the cycling performance in hydrogen isotope storage materials.

T-10 Tokamak Hydrocarbon Films as Storage of Hydrogen and Hydrocarbon Isotopes

The results of the study of the properties and structural features of amorphous hydrocarbon films CDx (x ~ 0.5) obtained in the plasma discharge of the T-10 tokamak are presented, which characterize these films as a hydrocarbon system with carbon sp3 + sp2 states (mainly with sp3 states). The films form a branched three-dimensional fractal carbon network with a fractal structure and a high specific surface. Such a CDx system facilitates accumulation and storage of both hydrogen isotopes and hydrocarbons in a stable state. Its desorption characteristics can be improved by the catalytic effect of iron impurities.

Achieving Excellent Cycle Stability in Zr-Nb-Co-Ni Based Hydrogen Isotope Storage Alloys by Controllable Phase Transformation Reaction

Achieving Excellent Cycle Stability in Zr-Nb-Co-Ni Based Hydrogen Isotope Storage Alloys by Controllable Phase Transformation Reaction

The free-standing nanoporous palladium for hydrogen isotope storage

Herein, we present hydrogen isotope storage properties of the free-standing monolithic nanoporous palladium (NP–Pd) with different microstructure feature sizes. The NP-Pd samples fabricated by dealloying from Pd–Al alloy and the samples possess high surface area with all of the open pores and ligaments both at nanoscale, which provide the large quantities of reaction sites. The NP-Pd exhibits efficient hydrogen (H2) separation property from deuterium (D2) with distinguishable absorbing and desorbing plateau pressures. The samples own high and reversible H2 and D2 storage capacities with the absorption values up to 0.61 and 0.595 at room temperature. The hydrogen isotope storage capacities increase with the ligament sizes of the NP-Pd samples, which have been high temperature annealed with the larger ligament size more than 10 nm. While for the fresh dealloyed NP-Pd samples with rough surface and ligament size much smaller than 10 nm, the capacity does not follow this behavior. Therefore, a theoretical model based on the existence of the different storage sites at subsurface and interior region is established, which can be used to predict the hydrogen absorption capacity of nanoporous Pd with different structure size. This work reveals both fundamental insights and practical guidance for nanoporous materials design and fabrication, which can be applied in hydrogen isotope separation and storage applications in green energy fields.

Research Progress on the Anti-Disproportionation of the ZrCo Alloy by Element Substitution.

Hydrogen-induced disproportionation (HID) during the cycles of absorption and desorption leads to a serious decline in the storage capacity of the ZrCo alloy, which has been recognized as the biggest obstacle to its application. Therefore, the prerequisite of a ZrCo application is to solve its anti-disproportionation problem in the field of rapid hydrogen isotope storage. Beyond surface modification and nanoball milling, this work systematically reviews the method of element substitution, which can obviously improve the anti-disproportionation. From a micro angle, as hydrogen atoms that occupy the 8e site in the ZrCoH3 lattice are instable and are considered to be the driving force of disproportionation, researchers believe that element substitution by changing the occupation of hydrogen atoms at the 8e site can improve the anti-disproportionation of the alloy. At present, Ti/Nb substitutions for the Zr terminal among substitute elements have an excellent anti-disproportionation performance. In this work, up-to-date research studies on anti-disproportionation and its disproportionation mechanism of the ZrCo alloy are introduced by combining experiments and simulations. Moreover, the optimization of the alloy based on the occupation mechanism of 8e sites is expected to improve the anti-disproportionation of the ZrCo alloy.

The functioning mechanism of Al valid substitution for Co in improving the cycling performance of Zr–Co–Al based hydrogen isotope storage alloys

In order to optimize the hydrogen isotope storage properties of ZrCo alloy and promote its application in the storage and delivery system (SDS), ZrCo alloy is modified by partial substitution of Co with Al and subsequent melt spinning process. The microstructure and hydrogen isotope storage properties, especially the cycling performance, of ZrCo1-xAlx (x = 0–0.15) samples were thoroughly investigated. It is found that all as-cast Al-substituted alloys are consisted of a main phase of ZrCo, while the segregation of Al element at grain boundary is more serious with the increase of Al doping content, which restrains the valid substitution content of Al for Co in ZrCo phase. The initial activation performances of the Al-substituted alloys are enhanced and excellent hydriding kinetics are maintained. With the increase of Al substitution content in ZrCo phase of ZrCo1-xAlx (x = 0–0.15) alloys, the initial saturated hydrogen capacities of α solid-solution phase are improved significantly, which is attributed to the decline of valence electron concentrations (VEC) for Al-substituted alloys. Further analysis shows that the hydrogenation-dehydrogenation process of ZrCo1-xAlx (x = 0–0.15) alloys after multiple cycles has been altered as intercalation and de-intercalation of hydrogen atoms between ZrCo phase and α phase, leading to cycling capacity stabilization. More importantly, the improved terminal saturated hydrogen capacities of α phase in the Al-substituted alloys, which represents enhanced final cycling stable capacities, is linked with the increase of initial saturated hydrogen capacities of α phase after Al substitution for Co in ZrCo phase. In addition, the valid substitution content of Al for Co in ZrCo phase is further increased without any element segregation for ZrCo0.9Al0.1 alloy processed by melt spinning, which behaves further optimized final cycling stable capacity of 0.93 wt%, and its variation of the hydrogenation and dehydrogenation paths is similar to those of the above samples. In this work, the mechanism of cycling capacity stabilization has been explored in detail, which provides guidance to improve the cycling stability of ZrCo-based hydrogen isotope storage alloys from point of phase structure of ZrCo alloy.

Numerical Comparison of Dehydriding Behaviors of Full-Scale Depleted Uranium Beds Equipped with Copper Foam or Copper Fins

In this study, a three-dimensional transient metal hydride model is applied to two different depleted uranium (DU) bed designs. One bed is designed to contain 1.86 kg DU for a hydrogen isotope storage capacity of 70 g, and it is loaded with copper foam to enhance internal heat transfer. The other bed is designed to contain 5.26 kg DU for a hydrogen isotope storage capacity of 200 g, and it uses copper fins to enhance internal heat transfer. A numerical study is conducted to analyze the dehydriding characteristics of two different DU bed designs. A parallel computing methodology is used to effectively reduce the computational turnaround time involved for full-scale DU bed geometries. The detailed simulation results show the evolution of temperature and hydrogen-to-metal atomic ratio contours at different hydrogen desorption stages and reveal the different DU dehydriding behaviors of the two DU beds. In sum, the present work elucidates the effects of key bed design parameters and helps identify optimal DU bed design strategies to effectively charge and discharge hydrogen isotopes.

Scale-Up Effects of Depleted Uranium (DU) Beds for Hydrogen Isotopes Storage

The purpose of this study is to investigate the influence of design parameters for the scale-up of the depleted uranium (DU) bed. The actual DU bed chosen for this study has a DU loading of 1.86 kg for a tritium capacity of 70 g and is cylindrical in shape and equipped with copper foam to enhance internal heat transfer. Based on the reference DU bed geometry, three different scale-up bed geometries to increase the amount of DU loading up to 9.3 kg were designed under different aspect ratios for comparison purposes and simulated using a three-dimensional transient DU hydride model developed in our previous studies. The simulation results are compared in terms of the evolution of the DU hydride temperature and H/U atomic ratio during the DU hydriding process. This study helps to identify key design parameters (e.g., it is critical to scale up the DU bed geometry).

Controlled Release of Hydrogen Isotopes from Hydride-Magnetic Nanomaterials.

In this work, hydrogen isotopes in the form of protium and deuterium were rapidly desorbed from magnetic-hydride iron oxide-palladium (Fe2O3-Pd) hybrid nanomaterials using an alternating magnetic field (AFM). Palladium (Pd), a hydride material with a well-known hydrogen isotope effect, was deposited on an Fe2O3 magnetic nanoparticle support by solution chemistries and used as a hydrogen isotope storage component. The morphological, structural, optical, and magnetic studies reveal that the Fe2O3-Pd nanoparticles are hybrid structures exhibiting both hydrogen isotope storage (Pd) and magnetic (Fe2O3) properties. The hydrogen isotope sorption/desorption behavior of metal hydride-magnetic nanomaterials was assessed by isothermal pressure-composition response curves (isotherms). The amount and rate of hydrogen isotope gas release was tuned by simply adjusting the strength of the magnetic field strength applied. Protium and deuterium displayed similar loading capacities, namely, H/M 0.55 and H/M = 0.45, but different plateau pressures. Significant differences in the kinetics of release for protium and deuterium during magnetic heating were observed. A series of magnetically induced charge-discharge cycling experiments were conducted showing that this is a highly reproducible and robust process.

A new strategy for remarkably improving anti-disproportionation performance and cycling stabilities of ZrCo-based hydrogen isotope storage alloys by Cu substitution and controlling cutoff desorption pressure

ZrCo1-xCux (x = 0–0.3) alloys for hydrogen isotope storage were prepared via induction levitation melting. The effects of partial substitution of Cu for Co on the microstructure, hydrogen storage properties including hydriding-dehydriding kinetics, thermodynamic characteristics, cycling stability and related mechanism have been systematically investigated. It is found that all synthesized alloy ingots consist of ZrCo main phase, the grain size is further refined but the segregation of Cu element at grain boundary is more serious with the increase of Cu content. The pressure-composition isotherms for dehydrogenation show that both ZrCoH3 and ZrCo0.9Cu0.1H3 hydrides undergo one-step desorption, while ZrCo0.8Cu0.2H3 and ZrCo0.7Cu0.3H3 hydrides experience two-step desorption since a new middle hydride phase of ZrCoH0.8 with CrB-type orthorhombic structure is discovered during their dehydrogenation. This result is proposed to be linked with the changed electronic structure and lattice distortion induced by Cu substitution. To compare their dehydriding kinetics, the apparent activation energies for hydrogen desorption of different hydride phases in the alloys are also calculated systematically, and the value of Ea for hydrogen desorption of ZrCoH3 phase is decreased from 118.02 kJ/mol to 95.90 kJ/mol, 77.98 kJ/mol and 78.65 kJ/mol, respectively. Prominent cycling stabilities of the Cu-substituted alloys are obtained and follow the trend: ZrCo0.8Cu0.2 > ZrCo0.7Cu0.3 > ZrCo0.9Cu0.1 > ZrCo. Specifically, the optimum cycling stable capacity of ZrCo-based alloy is increased from 0.4 wt % to 1.21 wt %. Furthermore, the ZrCo0.8Cu0.2 alloy exhibits further enhanced cycling stability during the cycle by controlling cutoff desorption pressure at 0.253 bar, where only the first-step dehydrogenation happens. Therefore, a new strategy for improving anti-disproportionation performance of ZrCo-based alloys by controlling cutoff desorption pressure is also proposed, which is in favor of the enhanced cycling stability and further application of Cu-substituted ZrCo-based alloys for hydrogen isotope storage and delivery in the International Thermonuclear Experimental Reactor (ITER).

Study on the modification of Zr-Mn-V based alloys for hydrogen isotopes storage and delivery

To ensure the safety and efficiency of hydrogen isotopes in the storage and delivery system (SDS), Zr-Mn-V based hydrogen isotopes storage alloys were prepared by induction levitation melting technique under Ar atmosphere. The effects of modification for Zr-Mn-V alloy of ZrMn2-xVx (x = 0, 0.4, 0.6, 0.8) and ZrMn1.4-yV0.6 (y = 0, 0.2, 0.4) on microstructure, hydriding kinetics, de-/hydrogenation thermodynamics, cycling stability and anti-disproportionation performance were systematically investigated. The results show that all alloys contain a main phase of ZrMn2 and little impure phase. Crucially, the lattice parameters of ZrMn2 phase increase after V substitution, as well as Mn decrease, leading the equilibrium pressure of dehydrogenation significantly decreases from 2.931 bar (ZrMn2-H) to 0.080 bar (ZrMn1.2V0.6-H) at 200 °C, and the corresponding enthalpy changes from 43.29 to 60.38 kJ mol−1 H2. Compared with ZrCo, ZrMn1.2V0.6 exhibits outstanding stability with 1.63 wt% during 20 cycles and scarcely losing on capacity through the anti-disproportionation measurement under the simulated SDS environment. Consequently, considering all the performances of ZrMn1.2V0.6 sample, it could be an alternative material for hydrogen isotopes storage and delivery to be applied in SDS.

Improvement on the kinetic and thermodynamic characteristics of Zr1-xNbxCo (x = 0–0.2) alloys for hydrogen isotope storage and delivery

In order to promote the application of ZrCo alloy in storage and delivery system of hydrogen isotope, Zr1-xNbxCo (x = 0–0.2) alloys were prepared by induction levitation melting method under argon atmosphere. The effects of Nb substitution for Zr on the microstructure, initial activation behavior, dehydrogenation thermodynamics, disproportionation behavior and cycling stability of Zr1-xNbxCo (x = 0–0.2) alloys were systematically investigated. The results show that all alloys contain a ZrCo main phase and a little secondary phase of ZrCo2. With the content of Nb increasing, the lattice parameters of ZrCo main phase decrease and the distribution of ZrCo2 secondary phase is more uniform. It is found that the initial activation period is remarkably reduced from 87.79 h for ZrCo to 8.08 h for Zr0.8Nb0.2Co. Meanwhile, the equilibrium pressure of hydrogen desorption is enhanced from 0.197 (x = 0) to 0.85 bar (x = 0.2) at 350 °C, which is beneficial to delivery of hydrogen isotope. Further experiments exhibit that the anti-disproportionation performance and cycling stability have been greatly improved after Nb partial substitution, which could be explained by the enlargement of the apparent activation energy from 147.8 kJ/mol (ZrCo) to 182.1 kJ/mol (Zr0.85Nb0.15Co) for disproportionation reaction.

Physicochemical conditions for effective hydrogen isotope storage and delivery in a uranium bed

This paper proposes physicochemical conditions for effective hydrogen isotope storage and delivery in a uranium bed. Effective physicochemical conditions for tritium storage and delivery are obtained by manipulating initial depleted uranium (DU) temperatures and hydrogen pressures and applying three distinct operation scenarios. These novel physicochemical conditions and operation scenarios enable higher and more constant hydrogen recovery and delivery rates. The results presented can be used to facilitate the storage and delivery of tritium for environmental protection and waste management in nuclear fission reactors, and for future commercial use in isotope industries and nuclear fusion fuel systems.