RESUMEN
Reversible solid-state hydrogen storage of magnesium hydride, traditionally driven by external heating, is constrained by massive energy input and low systematic energy density. Herein, a single phase of Mg2Ni(Cu) alloy is designed via atomic reconstruction to achieve the ideal integration of photothermal and catalytic effects for stable solar-driven hydrogen storage of MgH2. With the intra/inter-band transitions of Mg2Ni(Cu) and its hydrogenated state, over 85% absorption in the entire spectrum is achieved, resulting in the temperature up to 261.8 °C under 2.6 W cm-2. Moreover, the hydrogen storage reaction of Mg2Ni(Cu) is thermodynamically and kinetically favored, and the imbalanced distribution of the light-induced hot electrons within CuNi and Mg2Ni(Cu) facilitates the weakening of Mg-H bonds of MgH2, enhancing the "hydrogen pump" effect of Mg2Ni(Cu)/Mg2Ni(Cu)H4. The reversible generation of Mg2Ni(Cu) upon repeated dehydrogenation process enables the continuous integration of photothermal and catalytic roles stably, ensuring the direct action of localized heat on the catalytic sites without any heat loss, thereby achieving a 6.1 wt.% H2 reversible capacity with 95% retention under 3.5 W cm-2.
RESUMEN
Al batteries are promising post-Li battery technologies for large-scale energy storage applications owing to their low cost and high theoretical capacity. However, one of the challenges that hinder their development is the unsatisfactory plating/stripping of the Al metal anode. To circumvent this issue, an ultrathin MXene layer is constructed on the surface of Al by in situ chemical reactions at room temperature. The as-prepared flexible MXene film acts like armor to protect the Al-metal by its high ionic conductivity and high mechanical flexibility. The MXene endow the Al anode with a long cyclic life of more than 5000 h at ultrahigh current density of 50 mA cm-2 for Al//Al batteries and a retention of 100% over 200 cycles for 355 Wh kg-1 PTO//Al batteries. This work provides fresh insights into the formation and regulation of stable electrode-electrolyte interfaces as well as effective strategies for improving Al metal batteries.
RESUMEN
Constructing robust anode with strong aluminophilicity and rapid desolvation kinetics is essential for achieving high utilization, long-term durability, and superior rate performance in Al metal-based energy storage, yet remains largely unexplored. Herein, molybdenum nanoparticles embedded onto nitrogen-doped graphene (Mo@NG) are designed and prepared as Al host to regulate the deposition behavior and achieve homogeneous Al plating/stripping. The monodispersed Mo nanoparticles reduce the desolvation energy barrier and promote the deposition kinetics of Al. Additionally, Mo nanoparticles act as aluminophilic nucleation sites to minimize the Al nucleation overpotential, further guiding uniform and dense Al deposition. As a result, the dual-functional Mo@NG endows Al anodes with low voltage hysteresis, reversible Al plating/stripping with high coulombic efficiency, and excellent high-rate capability under 5 mA cm-2 . Moreover, the as-designed Al metal full batteries deliver a high capacity retention of 92.8% after 3000 cycles at 1 A g-1 . This work provides an effective solution to optimize the electrochemical properties of Al metal anode from the perspective of desolvation and deposition reactions, towards the development of high-safety and long-cycling aluminum-ion batteries.
RESUMEN
The lack of safe and efficient hydrogen storage is a major bottleneck for large-scale application of hydrogen energy. Reversible hydrogen storage of light-weight metal hydrides with high theoretical gravimetric and volumetric hydrogen density is one ideal solution but requires extremely high operating temperature with large energy input. Herein, taking MgH2 as an example, a concept is demonstrated to achieve solar-driven reversible hydrogen storage of metal hydrides via coupling the photothermal effect and catalytic role of Cu nanoparticles uniformly distributed on the surface of MXene nanosheets (Cu@MXene). The photothermal effect of Cu@MXene, coupled with the "heat isolator" role of MgH2 indued by its poor thermal conductivity, effectively elevates the temperature of MgH2 upon solar irradiation. The "hydrogen pump" effect of Ti and TiHx species that are in situ formed on the surface of MXene from the reduction of MgH2 , on the other hand, plays a catalytic role in effectively alleviating the kinetic barrier and hence decreasing the operating temperature required for reversible hydrogen adsorption and desorption of MgH2 . Based on the combination of photothermal and catalytic effect of Cu@MXene, a reversible hydrogen storage capacity of 5.9 wt% is achieved for MgH2 after 30 cycles using solar irradiation as the only energy source.
RESUMEN
Requiring high temperature for hydrogen storage is the main feature impeding practical application of light metal hydrides. Herein, to lift the restrictions associated with traditional electric heating, light is used as an alternative energy input, and a light-mediated catalytic strategy coupling photothermal and catalytic effects is proposed. With NaAlH4 as the initial target material, TiO2 nanoparticles uniformly distribute on carbon nanosheets (TiO2 @C), which couples the catalytic effect of TiO2 and photothermal property of C, is constructed to drive reversible hydrogen storage in NaAlH4 under light irradiation. Under the catalysis of TiO2 @C, complete hydrogen release from NaAlH4 is achieved within 7 min under a light intensity of 10 sun. Furthermore, owing to the stable catalytic and photothermal effect of TiO2 @C, NaAlH4 delivers a reversible capacity of 4 wt% after 10 cycles with a capacity retention of 85% under light irradiation only. The proposed strategy is also applicable to other light metal hydrides such as LiAlH4 and MgH2 , validating its universality. The concept of light-driven hydrogen storage provides an alternative approach to electric heating, and the light-mediated catalytic strategy proposed herein paves the way to the design of reversible high-density hydrogen storage systems that do not rely on artificial energy.
RESUMEN
Due to their high theoretical specific capacity, metal hydrides are considered to be one of the most promising anode material for all-solid-state Li-ion batteries. Their practical application suffers, however, from the poor cycling stability and sluggish kinetics. Herein, we report the in situ fabrication of MgH2 and Mg2NiH4 that are uniformly space-confined by inactive Nd2H5 frameworks with high Li-ion and electron conductivity through facile hydrogenation of single-phase Nd4Mg80Ni8 alloys. The formation of MgH2 and Mg2NiH4 nanocrystals could not only shorten Li-ion and electron diffusion pathways of the whole electrode but also relieve the induced stress upon volume changes. Additionally, the robust frameworks constructed by homogeneous distribution of inactive Nd2H5 based on a molecular level could effectively alleviate the volume expansion and phase separation of thus-confined MgH2 and Mg2NiH4. More importantly, it is theoretically and experimentally verified that the uniform distribution of Nd2H5, which is an electronic conductor with a Li-ion diffusion barrier that is much lower than that of MgH2 and Mg2NiH4, could further facilitate the electron and Li-ion transfer of MgH2 and Mg2NiH4. Consequently, the space-confined MgH2 and Mg2NiH4 deliver a reversible capacity of 997 mAh g-1 at 2038 mA g-1 after 100 cycles.
RESUMEN
Rechargeable aluminum-ion batteries (AIBs), using low-cost and inherent safety Al metal anodes, are regarded as promising energy storage devices next to lithium-ion batteries. Currently, one of the greatest challenges for AIBs is to explore cathodes suitable for feasible Al3+ insertion/extraction with high structure stability. Herein, a facile co-engineering on solid solution phase and cavity structure is developed via Prussian blue analogues by a simple and facile sulfidation strategy. The obtained uniform yolk-shell Fe0.4Co0.6S@N-doped carbon nanocages (y-s Fe0.4Co0.6S@NC) display a high reversible capacity of 141.3 mA h g-1 at 500 mA g-1 after 100 cycles and a good rate capability of 100.9 mA h g-1 at 1000 mA g-1. The improved performance can be mainly ascribed to the dual merits of the composite; that is, more negative Al3+ formation energy and improved Al3+ diffusion kinetics favored by the solid solution phase and Al3+ insertion/extraction accommodable space stemmed from the yolk-shell structure. Moreover, the reaction mechanism study discloses that the reaction involves the intercalation of Al3+ ions into Fe0.4Co0.6S to generate AllFemConS and elemental Fe and Co.
RESUMEN
Lithium hydride has been widely identified as the major component of the solid-electrolyte interphase of Li metal batteries (LMBs), but is often regarded as being detrimental to the stabilization of LMBs. Here, we identify the positive and important role of LiH in promoting fast diffusion of Li ions by building a unique three-dimensional (3D) Li metal anode composed of LiMg alloys uniformly confined into graphene-supported LiH nanoparticles. The built-in electric field at the interface between LiH with high Li ion conductivity and LiMg alloys effectively boosts Li diffusion kinetics toward favorable Li plating into lithiophilic LiMg alloys through the surface of LiH. Therefore, the diffusion coefficient of Li ions of the thus-formed 3D structured Li metal anode is 10 times higher than the identical anode without the presence of LiH, and it exhibits a long cycle life of over 1200 hours at 3 mA cm-2 under 5 mA hour cm-2.
RESUMEN
Transition-metal selenides are attractive cathode materials for rechargeable aluminum batteries (RABs) because of their high specific capacity, superior electrical properties, and low cost. To overcome the associated challenges of low structural stability and poor reaction kinetics, a spatial isolation strategy was applied to develop RAB cathodes comprising ultrafine CoSe2 particles embedded in nitrogen-doped porous carbon nanosheet (NPCS)/MXene hybrid materials; the two-dimensional NPCS structures were derived from the self-assembly of metal frameworks on MXene surfaces. This synthetic strategy enabled control over the particle size of the active materials, even at high pyrolysis temperature, thereby allowing investigations into the effect of size on the electrochemical behavior. Spectroscopic analysis revealed that the CoSe2-NPCS electrode exhibited a high discharge capacity (436 mAh g-1 at 1 A g-1), excellent rate capability (122 mA h g-1 at 5 A g-1), and long-term cycling stability (212 mAh g-1 after 500 cycles at 1 A g-1). Theoretical calculations regarding the Co adsorption affinities at various N-doping sites elucidated the synergistic effects of N-C/MXene hybrids for boosting the reaction kinetics and Co adsorption behavior in this system. This work offers an effective material engineering approach for designing electrodes with high rate stability for high-energy RABs.
RESUMEN
Red phosphorus (RP) has attracted great attention as a potential candidate for anode materials of high-energy density sodium-ion batteries (NIBs) due to its high theoretical capacity, appropriate working voltage, and natural abundance. However, the low electrical conductance and huge volumetric variation during the sodiation-desodiation process, causing poor rate performance and cyclability, have limited the practical application of RP in NIBs. Herein, we report a rational strategy to resolve these issues by encapsulating nanoscaled RP into conductive and networked carbon nanocages (denoted as RP@CNCs) using a combination of a phosphorus-amine based method and evacuation-filling process. The large interior cavities volume of CNCs and controllable solution-based method enable the ultrahigh RP loading amount (85.3 wt %) in the RP@CNC composite. Benefiting from the synergic effects of the interior cavities and conductive network, which afford high structure stability and rapid electron transport, the RP@CNC composite presents a high systematic capacity of 1363 mA h g-1 at a current density of 100 mA g-1 after 150 cycles, favorable high-rate capability, and splendid long-cycling performance with capacity retention over 80% after 1300 cycles at 5000 mA g-1. This prototypical design promises an efficient solution to maximize RP loading as well as to boost the electrochemical performance of RP-based anodes.
RESUMEN
Current methods for synthesizing nanoscale red phosphorus (NRP), including ball-milling and vaporization-condensation, have various limitations. More effective engineering of the properties of these materials would promote their application in sodium-ion batteries. Herein, we report a simple phosphorus-amine-based method for the scalable preparation of NRP with high yield. We confirm that red phosphorus is highly soluble in ethylenediamine and that addition of H+ precipitates a network of NRP, where the size distribution is controlled by the H+ concentration. Through the use of this method, uniform NRP with particle sizes of 5-10 nm was dispersed in situ on the surfaces of reduced graphene oxide (rGO) with a controllable loading ratio. We attribute the formation of this structure to strong adsorption between the red phosphorus-ethylenediamine complex and rGO. The binding between NRP/Na3P and rGO effectively stabilized the NRP on rGO throughout charging/discharging processes, therefore enabling the NRP-rGO composite to deliver a high capacity of 2057 mA h g-1 at a current density of 100 mA g-1 and excellent long-cycling performance.
