Magnesium hydrides (MgH 2 ) have been extensively studied for solid‐state storage applications. However, the industrial scalability of MgH 2 is limited due to its high absorption/ desorption temperatures and poor kinetics. In this work, a Nb‐substituted Mg 2 Ni catalyst (Mg 2 Ni 0.8 Nb 0.2 ) was synthesized by the melt spinning technique. The Mg‐20 wt% of Mg 2 Ni 0.8 Nb 0.2 composites were prepared using the high‐energy ball milling technique. The composite desorbed around 5 wt% H 2 within 10 min at 300 °C, while retaining 97.88% of its initial absorption capacity after 20 cycles. Furthermore, the composites were hydrogenated for different times, 10, 20, and 30 min, to study the effect of hydrogenation time on the dehydrogenation behaviour of MgH 2 . Compared with pure MgH 2 , which exhibits an activation energy of 275.52 kJ/mol, the Mg–Mg 2 Ni 0.8 Nb 0.2 composites showed significantly reduced activation energies of 126.35, 131.66, and 100.78 kJ/mol after hydrogenation for 10, 20, and 30 min, respectively. The improved performance is attributed to partial Nb substitution, which enhances hydrogen dissociation and reduces the activation energy for breaking Mg–H bonds.
Layered double hydroxides (LDHs) with hollow structures offer high theoretical specific capacity and short ion diffusion pathways, making them promising supercapacitor materials. However, constructing hollow NiCo‐LDH remains challenging because it typically relies on template or special reaction conditions that are often harsh, and the conventional preparation of LDHs itself requires large amounts of alkaline reagents. Herein, we report an alkali‐free nickel‐ion‐directed replacement reaction using ZIF‐67 as self‐sacrificing template to fabricate hollow NiCo‐LDH nanocages. Enabled by a Kirkendall‐effect‐mediated conversion process, this green strategy yields hollow dodecahedral nanocages providing abundant electroactive sites and facilitating rapid ion transport. The optimized electrode delivers a high specific capacity of 466.14 mAh g −1 at 1 A g −1 and retains 314.99 mAh g −1 at 10 A g −1 . Kinetic analysis reveals that the capacitive contribution increases from 52.8% at 5 mV s −1 to 83.3% at 100 mV s −1 , demonstrating excellent surface‐controlled charge storage. An asymmetric supercapacitor (NiCo‐LDH//AC) achieves a maximum energy density of 38.7 Wh kg −1 at 179.8 W kg −1 and retains 26.5 Wh kg −1 at 1798 W kg −1 , and powers an LED for over 100 min. This work offers a green, alkali‐free route to hollow bimetallic LDHs and highlights the potential of sustainable synthesis for high‐performance supercapacitors.
Lithium‐ion polypropylene (PP) separators limit high‐energy Li‐ion batteries due to poor thermal stability, low wettability, and weak dendrite suppression. Metal–organic frameworks (MOFs) provide a viable solution through tunable pores, high surface area, and versatile surface chemistry. This review summarizes multiscale regulation strategies for MOFs‐modified PP separators. It classifies applicable MOFs into three topological types—ZIF, UiO, and HKUST—and analyzes their distinct mechanisms in enhancing ion transport and interfacial dynamics. Four primary fabrication techniques (coating, blending, in situ growth, and composite construction) are systematically compared for their suitability and performance outcomes. Key challenges remain, including high costs, poor interface compatibility, and insufficient long‐term stability. Future development requires integrating multiscale structural engineering, intelligent dynamic interfaces, and cost‐effective green manufacturing. This review offers a practical framework for designing advanced separators for next‐generation high‐safety, high‐energy‐density Li‐ion batteries.
In this work, the structural, dynamical, electronic, optical, and thermodynamic properties of Hf 2 CCl 2 and Hf 2 CBr 2 MXene monolayers were investigated using density functional theory, the HSE06 hybrid functional, and ab initio molecular dynamics (AIMD) simulations. Phonon dispersion calculations together with AIMD simulations at 300 K confirm the dynamical and thermal stability of both monolayers. The optimized structures exhibit lattice constants of 3.411 and 3.479 Å and cohesive energies of −6.830 and −6.513 eV/atom for Hf 2 CCl 2 and Hf 2 CBr 2 , respectively. Electronic structure calculations indicate that both compounds are direct‐bandgap semiconductors with HSE06 bandgaps of 0.82 and 0.79 eV. These values correspond to the near‐infrared spectral region, making the two monolayers relevant for infrared optoelectronic applications. The calculated electron and hole effective masses are relatively small, suggesting favorable charge‐transport characteristics. In addition, both materials exhibit strong optical absorption, reaching values on the order of 10 5 cm −1 in the UV–visible region. Thermodynamic analysis further shows that the two systems remain stable over a wide temperature range up to 1000 K. Overall, these results highlight the potential of Hf 2 CCl 2 and Hf 2 CBr 2 monolayers for applications in optoelectronic and energy‐conversion technologies.
Battery equalization technology can enhance the consistency of battery packs and extend their service life. However, most existing equalization strategies tend to focus on increasing the equalization speed while neglecting temperature variations among individual cells, which poses significant safety risks. To address these issues, this paper proposes a joint state of charge (SOC)‐temperature active equalization strategy based on a dynamic grouping topology. First, a dynamic grouping topology integrating a reconfigurable circuit and a flying‐inductor is proposed, enabling energy transfer between any cells. Second, discrete dynamic models for SOC and temperature are respectively constructed, and the deviations of each variable from its mean are combined to form the optimization objective through an adaptive weighting method. Then, a Tent‐enhanced fireworks algorithm (Tent‐EFWA) is applied to optimize the charge/discharge decisions for each cell and generate the corresponding PWM control signals. Finally, simulation studies are conducted in MATLAB/Simulink. Compared with the traditional mean‐difference strategy, the temperature difference is reduced by 38.71% under static conditions, while under charging and discharging conditions, it is reduced by 48.35% and 58.62%, respectively. These results verify the effectiveness of the proposed strategy in improving both the consistency and safety of battery packs.
