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Magnesium hydride (MgH2) has been recognized as a promising anode material of lithium‐ion batteries (LIBs) owing to its ultrahigh specific capacity. The low conductivity and the structural pulverization induced by large volume expansion, however, has long limited its practical lithium storage performance. Herein, a series of yolk‐shell‐like structures, composed of porous MgH2 nanoparticles (NPs) decorated with Mg‐based composites through in‐situ solid‐gas reaction using MgH2 as both the reactant and the structural template, have been fabricated and uniformly dispersed on electronically conductive graphene. It could not only physically accommodate the volume change of MgH2 owing to the physical protection of Mg‐based composites and the formation of void space inside MgH2 NPs, but also effectively facilitate the transportation of electrons throughout the whole electrode. Particularly, the uniform decoration of ultrathin Mg(BH4)2 as the shell with thermodynamically favorable intercalation of lithium ions and low kinetic barrier for the lithium‐ion diffusion promotes facile transportation of lithium ions into active MgH2, which, coupled with the porous structure constructed by flexible graphene, effectively improves the ion conductivity of the electrode. The synergistic improvement in electronic and ionic conductivity leads to a high reversible capacity of 1651 mAh g−1 at 200 mA g−1 after 380 cycles. [ABSTRACT FROM AUTHOR]

Aluminum–Sulfur (Al–S) batteries are regarded as promising energy storage devices due to their high energy‐to‐price ratios and safety. However, they suffer from clumsy S ↔ Al2S3 reactions and short lifespans that limit their practical application. By combining the merits of adsorptive Cu, catalytic Co, and conductive N‐doped carbon matrix, the bimetals decorated N‐doped carbon (Cu1Co1@NC) enables smooth adsorption and conversion of polysulfides. Consequently, the S@Cu1Co1@NC exhibits excellent electrochemical performance (delivering a high capacity of 317.5 mAh g−1 after 320 cycles at 1.5 A g−1). Moreover, the Cu‐endowed strong Al affinity and robust 3D scaffold with Co‐enhanced conductivity can regulate Al3+ depositing/stripping and successfully suppress Al dendrites. As a result, the Cu1Co1@NC displays negligible Al nucleation overpotential and provides ultra‐long lifespan (>10 000 h) and exceptional reversible (Coulombic efficiency = 99.8–99.9%) Al3+ plating/stripping. Integrating all these advantages, a full Al–S cell constructed with Cu1Co1@NC as two‐in‐one hosts demonstrates excellent capacity retention with enhanced reversibility. This work provides insights into the design of promising Al–S batteries based on bifunctional CuCo bimetal and favorable 3D framework. [ABSTRACT FROM AUTHOR]

The integration of highly‐safe Mg anode and fast Li+ kinetics endows hybrid Mg2+/Li+ batteries (MLIBs) a promising future, but the practical application is circumvented by the lack of appropriate cathodes that enable the realization of an enough participation of Mg2+ in the reactions, resulting in a high dependence on Li+. Herein, the authors develop a series of size‐controllable nickel sulfide nanoparticles embedded in carbon nanofibers (NiS@C) with synergistic effect of particle diameter and carbon content as the cathode material for MLIBs. The optimized particle size is designed to maximize the utilization of the active material and remit internal stress, and appropriate carbon encapsulation efficiently inhibiting the pulverization of particles and accelerates the ability of conducting ions and electrons. In consequence, the representative NiS@C delivers superior electrochemical performance with a highest discharge capacity of 435 mAh g−1 at 50 mA g−1. Such conversion cathode also exhibits excellent rate performance and remarkable cycle life. Significantly, the conversion mechanism of NiS in MLIBs is unambiguously demonstrated for the first time, affirming the corporate involvement of both Mg2+ and Li+ at the cathodic side. This work underlines a guide for developing conversion‐type materials with high rate capability and cyclic performance for energy storage applications. [ABSTRACT FROM AUTHOR]

Abstract: Due to their ultrahigh theoretical capacity, metal borohydrides are considered to be one of the most promising candidate hydrogen storage materials. Their application still suffers, however, from high operating temperature, sluggish kinetics, and poor reversibility. Designing nanostructures is an effective way of addressing these issues, but seeking suitable approaches remains a big challenge. Here, a space‐confined solid‐gas reaction to synthesize Mg(BH4)2 nanoparticles supported on grapheme is reported, which serves as the structural support for the dispersed Mg(BH4)2 nanoparticles. More notably, density functional theory calculations reveal that graphene could weaken both the MgH bonds of MgH2 and BB bonds of B2H6, which could thermodynamically and kinetically facilitate the chemical transformation to synthesize Mg(BH4)2 with high purity. Because of the synergistic effects of both the significant reduction in particle size and the catalytic effect of graphene, an onset dehydrogenation temperature of ≈154 °C is observed for Mg(BH4)2 nanoparticles, and a complete dehydrogenation could be achieved at a temperature as low as 225 °C, with the formation of MgB2 as the by‐product. This work provides a new perspective to tailoring the thermodynamics and kinetics of chemical reactions toward the favorable synthesis of functional inorganic materials. [ABSTRACT FROM AUTHOR]

A unique general, large-scale, simple, and cost-effective strategy, i.e., foaming-assisted electrospinning, for fabricating various transition metal oxides into ultrafine nanoparticles (TMOs UNPs) that are uniformly embedded in hierarchically porous carbon nanofibers (HPCNFs) has been developed. Taking advantage of the strong repulsive forces of metal azides as the pore generator during carbonization, the formation of uniform TMOs UNPs with homogeneous distribution and HPCNFs is simultaneously implemented. The combination of uniform ultrasmall TMOs UNPs with homogeneous distribution and hierarchically porous carbon nanofibers with interconnected nanostructure can effectively avoid the aggregation, dissolution, and pulverization of TMOs, promote the rapid 3D transport of both Li ions and electrons throughout the whole electrode, and enhance the electrical conductivity and structural integrity of the electrode. As a result, when evaluated as binder-free anode materials in Li-ion batteries, they displayed extraordinary electrochemical properties with outstanding reversible capacity, excellent capacity retention, high Coulombic efficiency, good rate capability, and superior cycling performance at high rates. More importantly, the present work opens up a wide horizon for the fabrication of a wide range of ultrasmall metal/metal oxides distributed in 1D porous carbon structures, leading to advanced performance and enabling their great potential for promising large-scale applications. [ABSTRACT FROM AUTHOR]

Here, we report the fabrication of a graphene-wrapped nanostructured reactive hydride composite, i.e. , 2LiBH 4 -MgH 2 , made by adopting graphene-supported MgH 2 nanoparticles (NPs) as the nanoreactor and heterogeneous nucleation sites. The porous structure, uniform distribution of MgH 2 NPs, and the steric confinement by flexible graphene induced a homogeneous distribution of 2LiBH 4 -MgH 2 nanocomposite on graphene with extremely high loading capacity (80 wt%) and energy density. The well-defined structural features, including even distribution, uniform particle size, excellent thermal stability, and robust architecture endow this composite with significant improvements in its hydrogen storage performance. For instance, at a temperature as low as 350 °C, a reversible storage capacity of up to 8.9 wt% H 2 , without degradation after 25 complete cycles, was achieved for the 2LiBH 4 -MgH 2 anchored on graphene. The design of this three-dimensional architecture can offer a new concept for obtaining high performance materials in the energy storage field. [ABSTRACT FROM AUTHOR]

Due to its wide diffusion channels and high electronic conductivity, conversion-type transition metal-based chalcogenide cathode materials are endowed greater potential to implement high capacity in Mg-based batteries. However, large coulombic interactions and sluggish kinetics at high charge density perplex its electrochemical performance, and application of which is also seriously hindered by large volume expansion. Herein, we design a facile approach to in-situ fabricate ultrafine and well-dispersive carbon encapsulated NiS nanoparticles anchored on carbon cloth (NiS@C NPs/CC) through one-step carbonization and sulfuration of benzoate anion-intercalated Ni(OH) 2 on CC. The as-prepared NiS@C NPs/CC is employed as the binder-free cathode material for hybrid Mg2+/Li+ batteries (MLIBs), whose energy storage capability is largely enhanced due to well-dispersive NiS nanoparticles. The MLIB assembled with NiS@C NPs/CC cathode implements a superior reversible capacity of 437 mAh g−1 at 100 mA g−1 and exhibits long lifespan. Its small diameter of 13.2 nm greatly shortens the ion transport pathway, and traits of carbon confinement and self-assembly synergistically boost electric conductivity at the same time, which contribute to the impressive electrochemical performance. This work not only realizes favorable synthesis of ultrafine and well-dispersive nanoparticles materials derived from the intercalation of organic-anion, but inaugurates a novel avenue for the rational design of carbon coated binder-free electrode for applications. [Display omitted] • This work reports a strategy to synthesize well-dispersive carbon wrapped NiS nanoparticles anchored on carbon cloth. • The configuration of homogeneous nanoparticles vastly shorts ion transport pathway and enlarges expansion space. • The characteristics of carbon confinement and self-assembly synergistically accelerate electric conductivity. • The MLIB assembled with NiS@C NPs/CC cathode implements a superior reversible capacity and exhibits long lifespan. [ABSTRACT FROM AUTHOR]

Abstract: The LiBH4–MgH2 system has a high reversible hydrogen storage capacity. However, the hydrogen de/absorption kinetics has to be further enhanced for its practical application. Motivated by the possibility that the metal catalysts facilitating the dissociation and combination of hydrogen molecules and activating Mg–H and B–H bonds, a novel catalyst, ruthenium nanoparticles supported on multiwalled carbon nanotubes (Ru/C) is prepared and its effect on the hydrogen sorption properties of LiBH4–MgH2 systems is investigated. The experimental results show that the Ru/C catalyst is active in reducing the dehydrogenation temperature and enhancing the dehydrogenation kinetics. Furthermore, the reversible capacity is also markedly enhanced under moderate conditions, and the catalytically enhanced hydrogen absorption capacity persists well during three de/rehydrogenation cycles. [Copyright &y& Elsevier]

Abstract: Thermally induced dehydrogenation of LiBH4 catalyzed by carbon-supported Pt nanoparticles (Pt/C) shows superior dehydrogenation performance compared to dehydrogenation in the absence of catalyst, even at very low catalyst content. Pt nanoparticles are found to play a crucial role in the catalyzed rehydrogenation/dehydrogenation of LiBH4. For doping with 10wt.% catalyst of an average Pt particle diameter of ca. 4.7nm, thermal dehydrogenation of LiBH4 is found to start at ca. 280°C with total weight loss of 16.3wt.% for the full temperature range. With increased loading of catalyst within a LiBH4 sample, the dehydrogenation temperature at which the major loss of hydrogen occurs is found to decrease while the hydrogen release amount is found to increase. All the hydrogen, ca. 18.4wt.%, can be released from LiBH4 below 560°C at a catalyst doped level of 50wt.%. Importantly, we observed a reversible hydrogenation/dehydrogenation with a capacity of approximately 6.1wt.%, which is very close to the theoretical capacity of the mixture of Li5PtH3 and B16H20 that is likely formed during the hydrogenation/dehydrogenation process. [Copyright &y& Elsevier]

Abstract SnSb alloy is a promising anode material for lithium-ion batteries due to its high specific capacity. However, the large volume change in the process of charge/discharge causes significant pulverizing of SnSb alloy particles, which leads to a rapid capacity fading. This paper reports the synthesis of homogenous SnSb nanoparticles that are embedded in N-doped porous carbon nanofibers through electrospinning technique with LiN 3 serving as poregen agent. This distinctive structure prevents the direct contact of SnSb nanoparticles with the electrolyte and provides enough space for the volume change of SnSb alloy during the Li+ insertion/extraction process, enabling this material to deliver a high reversible capacity of 892 mA h g−1 after 100th cycle at 100 mA g−1, and a stable capacity of 487 mA h g−1 after 1000 cycles at 2000 mA g−1. These results highlight the importance of the synergistic effect of SnSb alloy nanoparticles and N-doped porous carbon nanofibers for the high performance of lithium-ion batteries. Highlights • N-doped porous carbon nanofibers were prepared by electrospinning and calcination. • Lithium azide functions as a porogen reagent to generate porous structures. • A capacity of 892 mA h g−1 can be maintained after 100 cycles at 100 mA g−1 for the anode material. [ABSTRACT FROM AUTHOR]

A simple solvent-free method to synthesize MgH 2 nanoparticles (MgH 2 NPs) uniformly grown on graphene nanosheets (GNs) has been reported in this paper. Based on the formation of MgH 2 by di-n-butylmagnesium ((C 4 H 9 ) 2 Mg) thermal decomposition under hydrogen pressure, the GNs were added as matrix to hinder the agglomeration and growing of MgH 2 NPs. The fabricated MgH 2 /GNs nanocomposites, in which MgH 2 NPs were homogenously growing in the graphene matrix, have been synthesized by the favorable adsorption energy between (C 4 H 9 ) 2 Mg and GNs. Resulting from the one-step solvent-free route, the generated MgH 2 NPs shows high hydrogen capacity and steady hydriding and dehydriding properties, without the interference of the synthetic medium. At the same time, the size of the fabricated MgH 2 NPs can be controlled by adjusting the mass ratio of MgH 2 to graphene, the various hydrogen pressure and temperature. Attributed to smaller size effect, well uniform distribution of high density MgH 2 NPs, and the agglomeration blocking ability of graphene, the MgH 2 /GNs-40 wt% exhibits the favorite hydrogen storage performance. [ABSTRACT FROM AUTHOR]

Transition-metals have emerged as promising catalyst candidates for improving the hydrogen storage properties of MgH2. However, the preparation of uniformly dispersed and extra-fine transition-metals catalysts with high catalytic activity still remains a challenge. In this paper, an electrospinning-based reduction approach is presented to generate nanostructured nickel catalyst, which is protected from irreversible fusion and aggregation in subsequent high-temperature pyrolysis, in carbon nanofibers (Ni@C) in situ. The obtained Ni@C reveals remarkable catalytic effect on improving the hydrogen storage properties of MgH2. For example, the MgH2-10 wt%Ni@C composite delivers dehydrogenation capacities of 5.79 wt% and 6.12 wt% at 280 °C and 300 °C, respectively, whereas the as-milled MgH2 hardly decomposes at the same temperature. By Arrhenius plots, the calculated Ea of the dehydrogenation of MgH2-10 wt%Ni@C is 93.08 kJ mol−1, which is 94.33 kJ mol−1 lower than that of the as-milled MgH2. Furthermore, the microstructure of Ni@C is remained during the re/dehydrogenation process and the Ni nanoparticles are still distributed homogeneously in the composite, accounting for the excellent cycling performance. This study could render combinations of ultrafine metal nanoparticles with carbon accessible, thereby, extending opportunities in catalytic applications for hydrogen storage. The homogeneously distributed Ni with refined particle size in carbon nanofibers has been synthesized successfully. A certain proportion of Ni@C and commercial MgH 2 were mechanically mixed by high-energy ball milling and the Ni@C were uniformly dispersed on the surface of MgH 2 , which enhanced the interface interaction and reduced the apparent activation energy of the dehydrogenation of MgH 2 -10 wt % Ni@C. Image 1 • Ni nanoparticles in-situ encapsulated in carbon nanofibers has been synthesized successfully by electrospinning technique. • The Ni@C catalyst was uniformly dispersed on the surface of MgH 2 by high-energy ball milling. • The MgH 2 -10 wt %Ni@C delivers a hydrogen release of 5.91 wt% in 500 s at 325 °C. • The hydrogen storage capacity of the MgH 2 -10 wt %Ni@C composite can be maintained without degradation after 20 cycles. [ABSTRACT FROM AUTHOR]