Mg-based hydrogen storage materials have drawn a lot of attention due to the merit of high hydrogen storage density, earth-abundant resources, and environmental friendliness. However, the slow kinetics, high hydrogen absorption/desorption temperature, and poor cycling stability of Mg-based hydrogen storage materials prevent them from being used on a large scale. The developments of new alloys, nano-structure control, catalytic modification, and multiphase composites, among other things, have made significant progress in Mg-based hydrogen storage materials in recent years. However, challenges still exist, such as high hydrogen storage capacity, moderate adsorption/desorption temperature, rapid reaction rate, and long cycling life. In this review paper, the types of hydrogen storage phases and their interface in Mg-based materials, and the control methods of their microstructure/interface characteristics are systematically summarized. The mechanism of the hydrogen storage phase, microstructure, and surface/interface modifications on the improved thermal/kinetic performance of hydrogen storage are highlighted. This review concludes with an outlook and prospects on the challenge of designing Mg-based hydrogen storage materials by controlling the hydrogen storage phase and the corresponding interface.

We demonstrate the growth of dendritic magnesium deposits with fractal morphologies exhibiting shear moduli in excess of values for polymeric separators upon the galvanostatic electrodeposition of metallic Mg from Grignard reagents in symmetric Mg-Mg cells. Dendritic growth is understood on the basis of the competing influences of reaction rate, electrolyte transport rate, and self-diffusion barrier.

China has the most abundant magnesium resources in the world. Magnesium and its alloys have the advantages of low density, high specific strength, good damping property, and exceptional electromagnetic-shielding and energy-storage characteristics. They are one of the most promising lightweight materials. The enhanced applications of magnesium alloys can save energy and reduce emissions and are significant to the new Chinese energy strategy. However, magnesium alloys have a hexagonal close-packed structure and exhibit relatively low ductility. A bottleneck in expanding the application of magnesium alloys is improving the ductility of magnesium alloys. For more than ten years, efforts have been made to improve the ductility and plastic deformation ability. Progress has been made in plastic-processing technologies of magnesium alloys. The novel alloy design theory “solid solution strengthening and ductilizing” and advanced preparation technologies such as “melt self-purification through varying temperature” have been established. Series of new magnesium alloys with good ductility and corresponding alloy grades have been developed, where the impurity content of iron can be reduced to below 10 × 10-6; the elongation was more than 60% for ultrahigh plasticity magnesium alloys and is above 10% for the ultrahigh-strength magnesium alloys (UTS > 550 MPa). New plastic-processing technologies, such as asymmetric extrusion, asymmetric rolling, asymmetric modification, cyclical multipass upsetting and squeezing, expansion control large ratio forging, and extrusion and forging composite forming, have been developed. These newly developed magnesium alloys and processing technologies weaken the basal texture in wrought magnesium alloys, improving the formability of sheets, tubes, profiles, and forgings and their product quality and reducing their product cost. These technologies have been successfully applied in the processing of magnesium sheets, pipe profiles, and forgings.

我国是世界上镁资源最为丰富的国家，镁及镁合金具有质轻、比强度高、阻尼减振、电磁屏蔽性能优良、储能特性好等优点，是最有潜力的轻量化材料之一，其推广应用对节能减排和能源转型战略具有重要意义。但镁合金具有密排六方晶体结构，塑性变形能力较差。如何改善镁合金的塑性变形能力是扩大镁合金应用的瓶颈问题之一。本文综述了10多年来，世界各国在改善镁合金塑性、提升镁合金塑性变形能力等方面所做的大量工作，及在镁合金塑性加工技术等方面取得的重要进展。发展了“固溶强化增塑”新型镁合金设计理论和“熔体变温自纯化”等关键制备技术，形成了一批高塑性变形镁合金材料和牌号，其中杂质Fe含量可降到10 × 10^-6以下，超高塑性镁合金延伸率可达到60%以上，超高强度(抗拉强度大于550 MPa)镁合金延伸率可以达到10%以上；开发了非对称挤压、非对称轧制、非对称改性、往复循环多道次镦挤开坯技术、扩收控制大比率锻造技术、挤锻复合成形技术等一批镁合金新型塑性加工技术。这些合金和技术使变形镁合金基面织构显著弱化，明显提高了变形镁合金板材、管型材和锻件的塑性成形能力和制品质量，产品成本大幅度降低，在板材、管型材和锻件制备加工中实现了成功应用。

Using first-principles calculations, we describe and compare atomistic lithiation, sodiation, and magnesiation processes in black phosphorous with a layered structure similar to graphite for Li-, Na-, and Mg-ion batteries because graphite is not considered to be an electrode material for Na- and Mg-ion batteries. The three processes are similar in that an intercalation mechanism occurs at low Li/Na/Mg concentrations, and then further insertion of Li/Na/Mg leads to a change from the intercalation mechanism to an alloying process. Li and Mg show a columnar intercalation mechanism and prefer to locate in different phosphorene layers, while Na shows a planar intercalation mechanism and preferentially localizes in the same layer. In addition, we compare the mechanical properties of black phosphorous during lithiation, sodiation, and magnesiation. Interestingly, lithiation and sodiation at high concentrations (Li2P and Na2P) lead to the softening of black phosphorous, whereas magnesiation shows a hardening phenomenon. In addition, the diffusion of Li/Na/Mg in black phosphorus during the intercalation process is an easy process along one-dimensional channels in black phosphorus with marginal energy barriers. The diffusion of Li has a lower energy barrier in black phosphorus than in graphite.

Rechargeable magnesium batteries have attracted wide attention for energy storage. Currently, most studies focus on Mg metal as the anode, but this approach is still limited by the properties of the electrolyte and poor control of the Mg plating/stripping processes. This paper reports the synthesis and application of Bi nanotubes as a high-performance anode material for rechargeable Mg ion batteries. The nanostructured Bi anode delivers a high reversible specific capacity (350 mAh/gBi or 3430 mAh/cm(3)Bi), excellent stability, and high Coulombic efficiency (95% initial and very close to 100% afterward). The good performance is attributed to the unique properties of in situ formed, interconnected nanoporous bismuth. Such nanostructures can effectively accommodate the large volume change without losing electric contact and significantly reduce diffusion length for Mg(2+). Significantly, the nanostructured Bi anode can be used with conventional electrolytes which will open new opportunities to study Mg ion battery chemistry and further improve its properties.

In this work we uncover a novel effect between concentration dependent ion pair formation and anion stability at reducing potentials, e.g., at the metal anode. Through comprehensive calculations using both first-principles as well as well-benchmarked classical molecular dynamics over a matrix of electrolytes, covering solvents and salt anions with a broad range in chemistry, we elucidate systematic correlations between molecular level interactions and composite electrolyte properties, such as electrochemical stability, solvation structure, and dynamics. We find that Mg electrolytes are highly prone to ion pair formation, even at modest concentrations, for a wide range of solvents with different dielectric constants, which have implications for dynamics as well as charge transfer. Specifically, we observe that, at Mg metal potentials, the ion pair undergoes partial reduction at the Mg cation center (Mg(2+) → Mg(+)), which competes with the charge transfer mechanism and can activate the anion to render it susceptible to decomposition. Specifically, TFSI(-) exhibits a significant bond weakening while paired with the transient, partially reduced Mg(+). In contrast, BH4(-) and BF4(-) are shown to be chemically stable in a reduced ion pair configuration. Furthermore, we observe that higher order glymes as well as DMSO improve the solubility of Mg salts, but only the longer glyme chains reduce the dynamics of the ions in solution. This information provides critical design metrics for future electrolytes as it elucidates a close connection between bulk solvation and cathodic stability as well as the dynamics of the salt.

Rational design of novel electrolytes with enhanced functionality requires fundamental molecular-level understanding of structure-property relationships. Here we examine the suitability of a range of organic solvents for non-aqueous electrolytes in secondary magnesium batteries using density functional theory (DFT) calculations as well as experimental probes such as cyclic voltammetry and Raman spectroscopy. The solvents considered include ethereal solvents (e.g., glymes) sulfones (e.g., tetramethylene sulfone), and acetonitrile. Computed reduction potentials show that all solvents considered are stable against reduction by Mg metal. Additional computations were carried out to assess the stability of solvents in contact with partially reduced Mg cations (Mg → Mg) formed during cycling (e.g., deposition) by identifying reaction profiles of decomposition pathways. Most solvents, including some proposed for secondary Mg energy storage applications, exhibit decomposition pathways that are surprisingly exergonic. Interestingly, the stability of these solvents is largely dictated by magnitude of the kinetic barrier to decomposition. This insight should be valuable toward rational design of improved Mg electrolytes.

Unlocking the full potential of rechargeable magnesium batteries has been partially hindered by the reliance on chloride-based complex systems. Despite the high anodic stability of these electrolytes, they are corrosive toward metallic battery components, which reduce their practical electrochemical window. Following on our new design concept involving boron cluster anions, monocarborane CB11H12(-) produced the first halogen-free, simple-type Mg salt that is compatible with Mg metal and displays an oxidative stability surpassing that of ether solvents. Owing to its inertness and non-corrosive nature, the Mg(CB11H12)2/tetraglyme (MMC/G4) electrolyte system permits standardized methods of high-voltage cathode testing that uses a typical coin cell. This achievement is a turning point in the research and development of Mg electrolytes that has deep implications on realizing practical rechargeable Mg batteries.© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Secondary non-aqueous magnesium-based batteries are a promising candidate for post-lithium-ion battery technologies. However, the uneven Mg plating behavior at the negative electrode leads to high overpotential and short cycle life. Here, to circumvent these issues, we report the preparation of a magnesium/black phosphorus (Mg@BP) composite and its use as a negative electrode for non-aqueous magnesium-based batteries. Via in situ and ex situ physicochemical measurements, we demonstrate that Mg ions are initially intercalated in black phosphorus two-dimensional structures, forming chemically stable MgP intermediates. After the formation of the intermediates, Mg electrodeposition reaction became the predominant. When tested in the asymmetric coin cell configuration, the Mg@BP composite electrode allowed stable stripping/plating performances for 1600 h (800 cycles), a cumulative capacity of 3200 mAh cm, and a Coulombic efficiency of 99.98%. Assembly and testing of the Mg@BP | |nano-CuS coin cell enabled a discharge capacity of 398 mAh g and an average cell discharge potential of about 1.15 V at a specific current of 560 mA g with a low decay rate of 0.016% per cycle for 225 cycles at 25 °C.© 2024. The Author(s).

A major bottleneck for the development of Mg batteries is the identification of liquid electrolytes that are simultaneously compatible with the Mg-metal anode and high-voltage cathodes. One strategy to widen the stability windows of current nonaqueous electrolytes is to introduce protective coating materials at the electrodes, where coating materials are required to exhibit swift Mg transport. In this work, we use a combination of first-principles calculations and ion-transport theory to evaluate the migration barriers for nearly 27 Mg-containing binary, ternary, and quaternary compounds spanning a wide chemical space. Combining mobility, electronic band gaps, and stability requirements, we identify MgSiN2, MgI2, MgBr2, MgSe, and MgS as potential coating materials against the highly reductive Mg metal anode, and we find MgAl2O4 and Mg(PO3)(2) to be promising materials against high-voltage oxide cathodes (up to similar to 3 V).

In recent decades rechargeable Mg batteries (RMB) technologies have attracted much attention because the use of thin Mg foils anodes may enable to develop high energy density batteries.  One of the most critical challenges for devolving  RMB is finding  suitable  electrolyte solutions that enable efficient and reversible Mg cells operation. Most RMB studies concentrate on the development of novel electrolyte systems, while only few studies have focused on the practical feasibility of using pure metallic Mg as the anode material. Pure Mg metal anodes have been demonstrated to be useful in studying the fundamentals of nonaqueous Mg electrochemistry. However, pure Mg metal may not be suitable for mass production of ultrathin foils (< 100 microns) due to its limited ductility. The metals industry overcomes this problem by using ductile Mg alloys. We demonstrate herein the feasibility of processing ultrathin Mg anodes in electrochemical cells by using AZ31 Mg alloys (3% Al; 1% Zn). Thin film Mg AZ31 anodes present reversible Mg dissolution and deposition behavior in complex ethereal Mg electrolytes solutions that is comparable to that of pure Mg foils. Moreover, we demonstrated that secondary Mg battery prototypes comprising ultrathin AZ31 Mg alloy  anodes (≈ 25 µm thick) and Mg x Mo 6 S 8 Chevrel phase cathodes exhibit cycling performance that is equal to that of similar cells containing thicker pure Mg foil anodes. The possibility of using of ultrathin processable Mg metal anodes is an important step in the realization of rechargeable Mg batteries.© 2021 Wiley-VCH GmbH.

Dendrite formation is a critical challenge for the applications of lithium (Li) metal anodes. In this work a new strategy is demonstrated to address this issue by fabricating an Li amalgam film on its surface. This protective film serves as a flexible buffer that affords repeated Li plating/stripping. In symmetric cells, the protected Li electrodes exhibit stable cycling over 750 hours at a high plating current and capacity of 8 mA cm and 8 mAh cm, respectively. Coupled with high-loading cathodes (ca. 12 mg cm ) such as LiFePO and LiNi Co Mn O, the protected hybrid anodes demonstrate significantly improved cell stability, indicating its reliability for practical development of Li metal batteries. Interfacial analyses reveal a unique plating-alloying synergistic function of the protective film, where Li beneath the film is actively involved in the electrode reactions upon cycling. Lithium amalgams enrich the alloy anode family and provide new perspectives for the rational design of dendrite-free anodes.© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rechargeable magnesium batteries have received extensive attention as the Mg anodes possess twice the volumetric capacity of their lithium counterparts and are dendrite-free. However, Mg anodes suffer from surface passivation film in most glyme-based conventional electrolytes, leading to irreversible plating/stripping behavior of Mg. Here we report a facile and safe method to obtain a modified Mg metal anode with a Sn-based artificial layer via ion-exchange and alloying reactions. In the artificial coating layer, MgSn alloy composites offer a channel for fast ion transport and insulating MgCl/SnCl bestows the necessary potential gradient to prevent deposition on the surface. Significant improved ion conductivity of the solid electrolyte interfaces and decreased overpotential of Mg symmetric cells in Mg(TFSI)/DME electrolyte are obtained. The coated Mg anodes can sustain a stable plating/stripping process over 4000 cycles at a high current density of 6 mA cm. This finding provides an avenue to facilitate fast ion diffusion kinetics of Mg metal anodes in conventional electrolytes.© The Author(s) 2019. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.

Rechargeable magnesium batteries (RMBs) have attracted tremendous attention in energy storage applications in term of high abundance, high specific capacity and remarkable safety of metallic magnesium (Mg) anode. However, a serious passivation of Mg anode in the conventional electrolytes leads to extremely poor plating/stripping performance, further hindering its applications. Herein, we propose a convenient method to construct an artificial interphase layer on Mg anode by substitution and alloying reactions between SbCl₃ and Mg. This Sb-based artificial interphase layer containing mainly MgCl₂ and Mg₃Sb₂ endows the significantly improved interfacial kinetics and electrochemical performance of Mg anode. The overpotential of Mg plating/stripping in conventional Mg(TFSI)₂/DME electrolytes is vastly reduced from over 2 V to 0.25-0.3 V. Combining experiments and calculations, we demonstrate that under the uniform distribution of MgCl₂ and Mg₃Sb₂, an electric field with a favorable potential gradient is formed on the anode surface, which enables swift Mg²⁺ migration. Meanwhile, this layer can inhibit the decomposition of electrolytes to protect anode. This work provides an in-depth exploration of the artificial solid-electrolyte interface (SEI) construction, and a more achievable and safe path to realize the application of metallic Mg anode in RMBs.