Hydride ion (H-) conduction materials have attracted significant attention for their potential in advanced clean energy storage and conversion. Moreover, understanding H- migration mechanisms is essential for controlling ionic transport in these materials and advancing next-generation energy technologies, given the quantum mechanical nature of hydrogen. Here, we investigate the role of nuclear quantum effects (NQEs) by comparing results obtained from thermostated ring polymer molecular dynamics (TRPMD) simulations with those from classical molecular dynamics (MD) simulations using a trained deep potential (DP) model. Our results show that the main manifestation of NQEs is not the conventional quantum tunneling often intuitively expected. Instead, they facilitate the cooperative H- migration mechanism at low temperatures. This is reflected in the increased mean square displacements (MSDs) and diffusion coefficients observed under these conditions. Notably, the temperature dependence of diffusion coefficients from TRPMD follows Arrhenius behavior, whereas that of classical MD deviates significantly at low temperatures. This work highlights the crucial role of NQEs in governing low-temperature transport and provides fundamental insights for the design of advanced H- conductors.

Significant progress has been made in materials development for hydride ion (H−) conduction and H−-mediated electrochemical devices. However, a gas-solid H− battery (g-HIB) that utilizes H2 and metals as the active materials of the electrodes and offers the potential for high capacity and energy density has yet to be developed. Here, a typical metal-hydrogen system, Mg-H2, is employed to build such a g-HIB. Experimental results validate that hydrogenation and dehydrogenation of the anode lead to electric energy output and input, respectively, in the Mg|3CeH3@BaH2|H2 developed. This g-HIB exhibits an initial capacity of 1,526 mAh/g and maintains a capacity retention of over 70% after 60 cycles. It operates effectively across a wide temperature range of −20°C to 90°C. The integration of this g-HIB with a secondary ion battery could create a novel hydrogen-electricity co-storage system that can be applied to hydrogen-electricity powertrains of fuel cell vehicles or drones to deliver a high hydrogen energy efficiency of 93.9%.

Lithium amide-lithium hydride composite (LiNH2-2LiH), a composite hydride with a high hydrogen capacity of 10.29 wt.%, has long been considered a promising candidate for hydrogen storage; however, its application is hindered by the thermodynamic stability and sluggish kinetics associated with N─H and Li─H bond cleavage and formation during thermally driven de/re-hydrogenation. Herein, we report that the photoexcitation of LiNH2 under UV illumination (0.8 W·cm-2) induces homolytic N─H bond cleavage and produces a distinctive photo-response with simultaneous evolution of H2, N2, and NH3. Coupling LiNH2 with LiH enables UV-driven hydrogen release with effective suppression of gaseous byproducts. Under high-intensity full-spectrum illumination (2.9  W·cm-2), the combined non-thermal and photothermal effects allow complete dehydrogenation of LiNH2-2LiH (>10.0 wt.%), and near-full reversibility over 6 cycles (capacity retention ca. 99%). We further realized direct hydrogen release from LiNH2-2LiH under natural sunlight. This photo-induced destabilization strategy provides a general route to activate strong bonds in amide-hydride composites and offers a promising approach toward solid-state hydrogen storage under mild conditions.

Using a CeH2|3CeH3@BaH2|NaAlH4 hydride-ion battery (HIB) model, we observed that capacity decay originates not only from the cathode material itself but also from anode potential drift caused by interfacial instability. We proposed stabilization strategies to mitigate these effects, highlighting that interfacial compatibility is crucial for the cycling stability of HIBs.

Hydride-ion (H-) electrochemistry offers a promising route for next-generation energy storage due to the low mass and high theoretical energy density of H-carriers. However, the development of rechargeable hydride-ion batteries has been impeded by the lack of suitable electrode materials capable of reversible H-insertion/extraction and by severe interfacial challenges in all-solid-state configurations. Rare-earth hydrides, particularly CeH3, exhibit remarkable dual hydride-ion and electron conductivity. The stable Fm 3 m crystal structure minimizes their volume variations during de/re-hydrogenation, e.g., the volume changes by about 1% from CeH3 to CeH2. These intrinsic properties enable CeH3 and CeH2 to be potential electrode materials for an all-solid-state hydride-ion battery. Using the recently developed hydride ion conductor CeH3@BaH2 as electrolyte, we built a CeH2|CeH3@BaH2|CeH3 battery which delivers an initial discharge capacity of 79.5 mA h g-1 and maintains 40 mA h g-1 after 175 cycles at room temperature. A tandem stack configuration achieving a voltage of similar to 0.7 V and a thick-electrode battery with an areal capacity exceeding 13 mA h cm-2 were also assembled, demonstrating superior structural stability and the potential for applications. This work highlights the great potential of rare-earth hydrides for advanced energy storage. (c) 2026 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Abstract Hydrogen storage remains a key challenge for widescale adoption of hydrogen as an energy vector. Lightweight complex hydrides offer high storage densities but suffer from hydrogen release/cyclability above the temperatures required for practical use. Here, we report on discoveries in ternary Reactive Hydride Composites (RHCs). We systematically tuned the LiBH₄ content in the well-established Mg(NH₂)₂ - LiH framework, achieving reversible hydrogen release at temperatures starting below 393 K and a capacity of 3.1 wt%; a decrease of 100 K compared to the Mg(NH₂)₂ - LiH system.This is a crucial step towards the use of complex hydride-based hydrogen carriers for stationary and onboard hydrogen storage applications. We demonstrate a reversible RHC within the utilisation range of low-grade waste heat from a fuel cell, alongside offering insight into the reaction pathways in these RHCs to inform the design of future materials.

Alkali metal-modified catalysts significantly enhance the hydrogen storage performance of MgH2, yet the fundamental mechanisms of their promotional effects remain poorly understood. This study systematically investigates how Na and K promote the hydrogenation of commercial Mg powder over TiO2-based catalysts through combined experimental and theoretical approaches. Experimental results demonstrate that Na/K-modified TiO2 dramatically improves Mg hydrogen absorption: the addition of 5 wt% K-TiO2 reduces the hydrogen absorption peak temperature from ca. 300 °C (pure Mg) to 90 °C. Notably, Mg + 5 wt% K-TiO2 achieves 5.5 wt% H2 absorption capacity within 60 min at 100 °C, representing a 37% improvement over TiO2-only composites. Density functional theory calculations reveal that electron transfer from Na and K to TiO2 creates an electron-enriched interface, substantially reducing the energy barriers for hydrogen dissociation and diffusion. These findings elucidate how alkali metal promoters modulate electronic structure and reaction kinetics, providing a mechanistic foundation for rational design of advanced hydrogenation catalysts.

Hydride ion (H-) is expected to promote innovation in hydrogen energy storage and conversion because of its unique characteristics of low mass and high redox potential. However, fast ion conduction, critical for advancing electrochemical technologies, remains a challenge for H- conductors. Mixed-anion hydrides exhibit tunability in both structure and functionality, positioning them as promising systems for H- conduction. However, their development is hindered by harsh synthesis conditions. Herein, we develop an approach that incorporates oxygen treatment under mild conditions of 0.4 MPa and 450 degrees C, thereby enabling the efficient synthesis of a novel mixed-anion oxynitride hydride (Ba3La2O4.4N0.81H0.77) from its precursory nitride hydride. Experimental and simulative results indicate that Ba3La2O4.4N0.81H0.77 crystallizes in the Pnma space group and that H- migration is vacancy-mediated. Consequently, Ba3La2O4.4N0.81H0.77 achieves an H- conductivity more than two orders of magnitude higher than its precursor, with an optimum conductivity of 2.52 x 10-2 S cm-1 at 420 degrees C. Using Ba3La2O4.4N0.81H0.77 as electrolyte, a primary hydride ion battery operating in a mid-temperature range is demonstrated. This finding underscores the promise of these materials in H--based energy storage applications such as hydride ion batteries and electrochemical cells.

Electrochemical devices using hydride ions (H-) as charge carriers offer significant potential for hydrogen-based energy storage and conversion. However, only very few H- based electrochemical devices have been demonstrated, lacking details regarding the hydride ion-mediated reaction processes. In this work, we find that the NaAlH4 electrode can utilize at least 5.6 wt % H via an H--mediated reaction under ambient conditions. Further, the differences between H--mediated electrochemical reactions and traditional thermochemical processes are discussed from the perspectives of driving force, mass migration, and reaction kinetics. The thermally driven process is controlled by the enthalpy-entropy balance and the long-range mass transport. In contrast, the electrochemical pathway is driven by an electrochemical potential gradient and dominated by fast H- migration. Analyses of the interface and phase spatial distribution show that the electrode/electrolyte interfaces exhibit good compatibility at mild reaction conditions and suppression of detrimental phase separation. These findings highlight the unique advantages of H--mediated electrochemistry and provide a foundation for developing next-generation hydride-based energy storage and conversion technologies.

The poor stability of the interface between an electrode and an electrolyte leads to the occurrence of potential change.

Hydrogen storage remains a key challenge for widescale adoption of hydrogen as an energy vector. Lightweight complex hydrides offer high storage densities but suffer from hydrogen release/cyclability above the temperatures required for practical use. Here, we report on exciting novel discoveries in ternary Reactive Hydride Composites (RHCs). We systematically tuned the LiBH₄ content in the well-established Mg(NH₂)₂ - LiH framework, achieving reversible hydrogen release at temperatures starting as low as 350 K (77 ˚C) and a capacity of 3.1 wt%; a decrease of 100 K compared to the Mg(NH₂)₂ - LiH system. This is a crucial step towards the use of complex hydride-based hydrogen carriers for stationary and onboard hydrogen storage applications at ambient temperatures. These results offer insight into the reaction pathways in these RHCs and new insights for the design of next-generation solid-state hydrogen storage materials.

Owing to high thermal stability and large reaction enthalpy, MgH2 has high reaction temperatures and sluggish reaction kinetics in the dehydrogenation process, which consumes lots of energy. To achieve hydrogen release with low energy consumption, accelerated reaction rate, and high heating uniformity, this paper proposes a novel method of graphite responsive microwave-assisted thermal management with NaTiOxH catalyst. A multi-physics model of the 5 wt% NaTiOxH catalyzed MgH2 reactor integrated with a microwave generator is developed to investigate the reaction, heat and mass transfer process of hydrogen release. It is found that the graphite responsive microwave heating method could improve the temperature uniformity of reaction bed, reduce the energy consumption by at least 10.71% and save the hydrogen release time by 53.49% compared with the traditional electric heating method. Moreover, the hydrogen desorption thermodynamics could be improved with the increase of microwave power. The hydrogen release time is shortened by 19.55% with the increase of 20 W microwave power. Meanwhile, it is also concluded that the microwave excitation frequency of 2.1 GHz and the graphite content of 2 wt% have better heating performance. Therefore, it can be verified that the graphite responsive microwave heating helps to low-energy and accelerated hydrogen release from MgH2 hydrogen storage reactor.

As a negative charge carrier, the hydride ion (H-) is more energetic, polarizable and reactive than cations1. An H--mediated electrochemical process is fundamentally different from existing systems and enables the development of innovative electrochemical devices, such as rechargeable batteries, fuel cells, electrolysis cells and gas separation membranes2. Here we developed a core-shell hydride 3CeH3@BaH2, which exhibits fast H- conduction at ambient temperature and becomes a superionic conductor above 60 °C. This hydride allows us to construct an all-solid-state rechargeable H- battery CeH2|3CeH3@BaH2|NaAlH4, which operates at ambient conditions using NaAlH4 and CeH2 as cathode and anode materials, respectively. This battery has an initial specific capacity of 984 mAh g-1 and retains 402 mAh g-1 after 20 cycles. Using hydrogen as charge carriers can avoid the formation of detrimental metal dendrites, in principle, which creates new research avenues for clean energy storage and conversion.

The absence of safe and efficient hydrogen storage technologies is the major bottleneck for widespread applications of hydrogen energy. Reactive hydride composites with high gravimetric and volumetric hydrogen densities are ideal hydrogen storage materials. However, their traditional dehydrogenation processes normally involving electric-thermal-chemical energy conversion require high operating temperatures and substantial energy inputs to heat the reactor and oven. In this study, using LiBH4-2LiNH2 as a model system, that rapid dehydrogenation via a photo-thermal-chemical and/or photo-chemical energy conversion initiated by direct light irradiation is demonstrated and can be fulfilled in the presence of a catalyst and a photothermal agent. The experimental results revealed that the non-thermal effect of UV light plays a critical role in reducing the desorption temperature and enhancing the dehydrogenation kinetics. The collective photothermal and non-thermal effects drove over 8.0 wt.% hydrogen desorption from LiBH4-2LiNH2 within 5 min, which is ≈60 times faster than the thermal dehydrogenation process at the same temperature.

The Mg(NH2)2-2LiH composite has garnered extensive attention on account of its high theoretical hydrogen storage capacity (5.6 wt%) and favorable thermodynamic properties (ca. 40 kJ/mol-H2). However, the sluggish kinetics restricts its practical application. In this study, we investigated in detail the effect of BaH2 doping on the hydrogen absorption and desorption properties of Mg(NH2)2-2LiH. Experimental results demonstrated that the incorporation of BaH2 significantly enhances the hydrogen absorption/desorption kinetic performance compared to the pristine sample. The optimum overall performance was achieved for the sample doped with 0.05 BaH2. Its initial hydrogen release temperature and peak dehydrogenation temperature were decreased by 30 and 20 degrees C, respectively. The rate of hydrogen release during isothermal dehydrogenation at 160 degrees C was twice as fast as that of the undoped sample, and the interrelated activation energy was reduced from 112.8 to 72.2 kJ/mol. Additionally, the mechanism underlying improvement of the hydrogen storage performance in the Mg(NH2)2-2LiH composite by BaH2 was elucidated.

Progresses have been made in materials development for hydride ion (H−) conduction and H−-mediated electrochemical devices such as all-solid-state hydride ion batteries and cells. Gas-solid hydride ion battery (g-HIB), using H2 and light-weight metals as active materials of cathode and anode, respectively, offers potential for high capacity and energy density but has yet to be developed. Here, a typical metal-hydrogen system, Mg-H2, is employed to build such a g-HIB using the newly developed 3CeH3@BaH2 as electrolyte and LaNi5 as electrocatalyst. Experimental results validate that hydrogenation and dehydrogenation of the anode lead to electric energy output and input, respectively, over the Mg|3CeH3@BaH2|H2 developed. This g-HIB exhibits an initial capacity of 1526 mAh/g and maintains a capacity retention of over 70% after 60 cycles. It operates effectively across a wide temperature range of –20 to 90 ℃. Upon stacking, the battery generates an output voltage of 2.4 V and can power an LED bulb.

Hydride ion (H−) conductors have drawn much attention due to their potential applications in hydride-ion-based devices. Rare earth metal hydrides (REHx) have fast H− conduction which, unfortunately, is accompanied by detrimental electron conduction preventing their application as ion conductors. Here, REHx (RE = Nd, Ce, and Pr) with varied grain sizes, rich grain boundaries, and defects have been prepared by ball milling and subsequent sintering. The electronic conductivity of the ball-milled REHx samples can be reduced by 2–4 orders of magnitude compared with the non-ball-milled samples. The relationship of electron conduction and miscrostructures in REHx is studied and discussed based on experimental data and previously-proposed classical and quantum theories. The H− conductivity of all REHx is about 10−4 to 10−3 S cm−1 at room temperature, showing promise for the development of H− conductors and their applications in clean energy storage and conversion.

A recent finding shows that lattice deformation could transform the mixed electronic/hydride (H − ) conducting lanthanum trihydride (LaH 3 ) to a superionic H − conductor. Such a feature would enable the development of a brand-new all-solid-state hydride ion battery. It is essential to elucidate the mechanism of such a phenomenon. Here, we disclose an abnormal freezing effect on the electronic conductivity ( σ e ) of the ball-milled LaH 3 ; that is, σ e can be lowered by over 2 orders of magnitude upon a low-temperature treatment. Low-temperature Raman reveals that at low temperatures, lattice deformation has a noticeable influence on the interaction of hydrogen at octahedral (H o ) and tetrahedral (H t ) sites, which may play a crucial role in hindering electron conduction. This freezing effect can significantly improve the ionic transfer number of rare earth-based H − conductors and provide a new direction to the development of solid electrolytes for low-temperature all-solid-state batteries.