Micro-selection and Macro-orientation Strategy Enables High-Areal-Capacity Magnesium Metal Anode

Developing magnesium (Mg) metal electrodes for extended cycling at practical areal capacities is crucial for the commercialization of Mg battery commercialization. However, a higher areal-capacity operation requires greater Mg nucleation ability, which is further complicated by the fact that Mg faces a higher desolvation barrier than Li. This study investigates the correlation between the operated areal capacity and a short circuit. Accelerated lifespan degradation (670 to 15 h) occurs with increased areal capacity due to a short circuit from uneven Mg plating. Using insights, a micro-selection and macro-orientation strategy inspired by glass fiber-MXene (GF-MXene) substrate is developed for controlling Mg plating/stripping at high areal capacity. Synchronous morphological analysis reveals selective Mg plating on microscale MXene sheets and oriented plating/stripping in the macroscopic substrate greatly mitigates short circuiting, delivering high Coulombic efficiency (∼99.4%) for 700 h under 2.5 mAh cm–2 and extended cycle life (340 h) at 5 mAh cm–2, providing practical possibilities for Mg metal anodes applications

Micro-selection and Macro-orientation Strategy Enables High-Areal-Capacity Magnesium Metal Anode

Developing magnesium (Mg) metal electrodes for extended cycling at practical areal capacities is crucial for the commercialization of Mg battery commercialization. However, a higher areal-capacity operation requires greater Mg nucleation ability, which is further complicated by the fact that Mg faces a higher desolvation barrier than Li. This study investigates the correlation between the operated areal capacity and a short circuit. Accelerated lifespan degradation (670 to 15 h) occurs with increased areal capacity due to a short circuit from uneven Mg plating. Using insights, a micro-selection and macro-orientation strategy inspired by glass fiber-MXene (GF-MXene) substrate is developed for controlling Mg plating/stripping at high areal capacity. Synchronous morphological analysis reveals selective Mg plating on microscale MXene sheets and oriented plating/stripping in the macroscopic substrate greatly mitigates short circuiting, delivering high Coulombic efficiency (∼99.4%) for 700 h under 2.5 mAh cm–2 and extended cycle life (340 h) at 5 mAh cm–2, providing practical possibilities for Mg metal anodes applications

Facile Synthesis of Novel Heterostructure Based on SnO₂ Nanorods Grown on Submicron Ni Walnut with Tunable Electromagnetic Wave Absorption Capabilities

In this work, the magnetic–dielectric core-shell heterostructure composites with the core of Ni submicron spheres and the shell of SnO₂ nanorods were prepared by a facile two-step route. The crystal structure and morphology were investigated by X-ray diffraction analysis, transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM). FESEM and TEM measurements present that SnO₂ nanorods were perpendicularly grown on the surfaces of Ni spheres and the density of the SnO₂ nanorods could be tuned by simply varying the addition amount of Sn²⁺ in this process. The morphology of Ni/SnO₂ composites were also determined by the concentration of hydrochloric acid and a plausible formation mechanism of SnO₂ nanorods-coated Ni spheres was proposed based on hydrochloric acid concentration dependent experiments. Ni/SnO₂ composites exhibit better thermal stability than pristine Ni spheres based on thermalgravimetric analysis (TGA). The measurement on the electromagnetic (EM) parameters indicates that SnO₂ nanorods can improve the impedance matching condition, which is beneficial for the improvement of electromagnetic wave absorption. When the coverage density of SnO₂ nanorod is in an optimum state (diameter of 10 nm and length of about 40–50 nm), the optimal reflection loss (RL) of electromagnetic wave is −45.0 dB at 13.9 GHz and the effective bandwidth (RL below −10 dB) could reach to 3.8 GHz (12.3–16.1 GHz) with the absorber thickness of only 1.8 mm. By changing the loading density of SnO₂ nanorods, the best microwave absorption state could be tuned at 1–18 GHz band. These results pave an efficient way for designing new types of high-performance electromagnetic wave absorbing materials

Morphology-Control Synthesis of a Core–Shell Structured NiCu Alloy with Tunable Electromagnetic-Wave Absorption Capabilities

In this work, dendritelike and rodlike NiCu alloys were prepared by a one-pot hydrothermal process at various reaction temperatures (120, 140, and 160 °C). The structure and morphology were analyzed by scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction, and transmission electron microscopy, which that demonstrate NiCu alloys have core–shell heterostructures with Ni as the shell and Cu as the core. The formation mechanism of the core–shell structures was also discussed. The uniform and perfect dendritelike NiCu alloy obtained at 140 °C shows outstanding electromagnetic-wave absorption properties. The lowest reflection loss (RL) of −31.13 dB was observed at 14.3 GHz, and the effective absorption (below −10 dB, 90% attenuation) bandwidth can be adjusted between 4.4 and 18 GHz with a thin absorber thickness in the range of 1.2–4.0 mm. The outstanding electromagnetic-wave-absorbing properties are ascribed to space-charge polarization arising from the heterogeneous structure of the NiCu alloy, interfacial polarization between the alloy and paraffin, and continuous micronetworks and vibrating microcurrent dissipation originating from the uniform and perfect dendritelike shape of NiCu prepared at 140 °C

Electrostatic Shielding Guides Lateral Deposition for Stable Interphase toward Reversible Magnesium Metal Anodes

Compared with lithium, magnesium shows a low propensity toward dendritic deposition due to its low surface self-diffusion barriers. However, due to the intrinsic surface roughness of the metal and the nonuniformity of the formed solid–electrolyte interphase, uneven deposition of Mg still happens, which brings about high local current density and continuous proliferation of the interphase, greatly exacerbating the passivation. Unfortunately, little attention has been paid to the deposition uniformity and the interfacial stability of Mg metal anodes, which result in a potential penalty. Herein, we modify the electrolyte with cathodically stable cations to guide smooth deposition via an electrostatic shielding strategy. The cations adsorbed on the initial protuberances effectively homogenize the charge flux by repulsing the incoming Mg2+ away from the tips. Importantly, we prove the lateral growth can benefit the interphase stability and electrochemical reversibility

Preparation of Honeycomb SnO₂ Foams and Configuration-Dependent Microwave Absorption Features

Ordered honeycomb-like SnO₂ foams were successfully synthesized by means of a template method. The honeycomb SnO₂ foams were analyzed by X-ray diffraction (XRD), thermogravimetric and differential scanning calorimetry (TG-DSC), laser Raman spectra, scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR). It can be found that the SnO₂ foam configurations were determined by the size of polystyrene templates. The electromagnetic properties of ordered SnO₂ foams were also investigated by a network analyzer. The results reveal that the microwave absorption properties of SnO₂ foams were dependent on their configuration. The microwave absorption capabilities of SnO₂ foams were increased by increasing the size of pores in the foam configuration. Furthermore, the electromagnetic wave absorption was also correlated with the pore contents in SnO₂ foams. The large and high amounts pores can bring about more interfacial polarization and corresponding relaxation. Thus, the perfect ordered honeycomb-like SnO₂ foams obtained in the existence of large amounts of 322 nm polystyrene spheres showed the outstanding electromagnetic wave absorption properties. The minimal reflection loss (RL) is −37.6 dB at 17.1 GHz, and RL less than −10 dB reaches 5.6 GHz (12.4–18.0 GHz) with thin thickness of 2.0 mm. The bandwidth (<−10 dB, 90% microwave dissipation) can be monitored in the frequency regime of 4.0–18.0 GHz with absorber thickness of 2.0–5.0 mm. The results indicate that these ordered honeycomb SnO₂ foams show the superiorities of wide-band, high-efficiency absorption, multiple reflection and scatting, high antioxidation, lightweight, and thin thickness

Solvation Sheath Engineering by Multivalent Cations Enabling Multifunctional SEI for Fast-Charging Lithium-Metal Batteries

With the pursuit of high energy and power density, the fast-charging capability of lithium-metal batteries has progressively been the primary focus of attention. To prevent the formation of lithium dendrites during fast charging, the ideal solid electrolyte interphase should be capable of concurrent fast Li+ transport and uniform nucleation sites; however, its construction in a facile manner remains a challenge. Here, as Al3+ has a higher charge and Al metal is lithiophilic, we tuned the Li+ solvation structure by introducing LiNO3 and aluminum ethoxide together, resulting in the dissolution of LiNO3 and the simultaneous generation of fast ionic conductor and lithiophilic sites. Consequently, our approach facilitated the deposition of lithium metal in a uniform and chunky way, even at a high current density. As a result, the Coulombic efficiency of the Li||Cu cell increased to over 99%. Moreover, the Li||LiFePO4 full cell demonstrated significantly enhanced cycling performance with a remarkable capacity retention of 94.5% at 4 C, far superior to the 46.1% capacity retention observed with the base electrolyte

Yolk–Shell Ni@SnO₂ Composites with a Designable Interspace To Improve the Electromagnetic Wave Absorption Properties

In this study, yolk–shell Ni@SnO₂ composites with a designable interspace were successfully prepared by the simple acid etching hydrothermal method. The Ni@void@SnO₂ composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results indicate that interspaces exist between the Ni cores and SnO₂ shells. Moreover, the void can be adjusted by controlling the hydrothermal reaction time. The unique yolk–shell Ni@void@SnO₂ composites show outstanding electromagnetic wave absorption properties. A minimum reflection loss (RL_min) of −50.2 dB was obtained at 17.4 GHz with absorber thickness of 1.5 mm. In addition, considering the absorber thickness, minimal reflection loss, and effective bandwidth, a novel method to judge the effective microwave absorption properties is proposed. On the basis of this method, the best microwave absorption properties were obtained with a 1.7 mm thick absorber layer (RL_min= −29.7 dB, bandwidth of 4.8 GHz). The outstanding electromagnetic wave absorption properties stem from the unique yolk–shell structure. These yolk–shell structures can tune the dielectric properties of the Ni@air@SnO₂ composite to achieve good impedance matching. Moreover, the designable interspace can induce interfacial polarization, multiple reflections, and microwave plasma

Additional file 1 of Prevalence and correlates of disability among urban–rural older adults in Southwest China: a large, population-based study

Additional file 1