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Cost-effective, safe, and highly performing energy storage devices require rechargeable batteries, and among various options, aqueous zinc-ion batteries (ZIBs) have shown high promise in this regard. As a cathode material for the aqueous ZIBs, manganese dioxide (MnO2) has been found to be promising, but certain drawbacks of this cathode material are slow charge-transfer capability and poor cycling performance. Herein, a novel design of graphene quantum dots (GQDs) integrated with Zn-intercalated MnO2 nanosheets is put forward to construct a 3D nanoflower-like GQDs@ZnxMnO2 composite cathode for aqueous ZIBs. The synergistic coupling of GQDs modification with Zn intercalation provides abundant active sites and conductive medium to facilitate the ion/electron transmission, as well as ensure the GQDs@ZnxMnO2 composite cathode with enhanced charge-transfer capability and high electrochemical reversibility, which are elucidated by experiment results and in-situ Raman investigation. These impressive properties endow the GQDs@ZnxMnO2 composite cathode with superior aqueous Zn2+ storage capacity (∼403.6 mAh·g−1), excellent electrochemical kinetics, and good structural stability. For actual applications, the fabricated aqueous ZIBs can deliver a substantial energy density (226.8 W·h·kg−1), a remarkable power density (650 W·kg−1), and long-term cycle performance, further stimulating their potential application as efficient electrochemical storage devices for various energy-related fields. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous magnesium-ion batteries (MIBs) show great promise for low-cost, high-safety, and high-performance energy storage applications. Although manganese dioxide (MnO2) is considered as a potential electrode material for aqueous MIBs, the low electrical conductivity and unsatisfactory cycling performance greatly hinder the practical application of MnO2 electrode. To overcome these problems, herein, a novel Mg-intercalation engineering approach for MnO2 electrode to be used in aqueous MIBs is presented, wherein the structural regulation and electrochemical performance of the Mg-intercalation MnO2 (denoted as MMO) electrode were thoroughly investigated by density functional theory (DFT) calculations and in-situ Raman investigation. The results demonstrate that the Mg intercalation is essential to adjusting the charge/ion state and electronic band gap of MMO electrode, as well as the highly reversible phase transition of the MMO electrode during the charging-discharging process. Because of these remarkable characteristics, the MMO electrode can be capable of delivering a significant specific capacity of ∼419.8 mAh·g−1, while exhibiting a good cycling capability over 1000 cycles in 1 M aqueous MgCl2 electrolyte. On the basis of such MMO electrode, we have successfully developed a soft-packaging aqueous MIB with excellent electrochemical properties, revealing its huge application potential as the efficient energy storage devices. [ABSTRACT FROM AUTHOR]

The out-of-plane stability of the two-hinged space truss circular arch with a rectangular section is theoretically and numerically investigated in this paper. Firstly, the flexural stiffness and torsional stiffness of space truss arches are deduced. The calculation formula of out-of-plane elastic buckling loads of the space truss arch is derived based on the classical solution of out-of-plane flexural-torsional buckling loads of the solid web arch. However, since the classical solution cannot be used for the calculation of the arch with a small rise-span ratio, the formula for out-of-plane elastic buckling loads of space truss arches subjected to end bending moments is modified. Numerical research of the out-of-plane stability of space truss arches under different load cases shows that the theoretical formula proposed in this paper has good accuracy. Secondly, the design formulas to predict the out-of-plane elastoplastic stability strength of space truss arches subjected to the end bending moment and radial uniform load are presented through introducing a normalized slenderness ratio. By assuming that all components of space truss circular arches bear only axial force, the design formulas to prevent the local buckling of chord and transverse tubes are deduced. Finally, the bearing capacity design equations of space truss arches are proposed under vertical uniform load. [ABSTRACT FROM AUTHOR]

Benefiting from high flexibility and weavability, the wire-shaped supercapacitors (SCs) arouse tremendous interests for the applications in wearable/portable electronics. Graphene fiber (GF) is considered as a promising linear electrode for wire-shaped SCs. However, the bottleneck is how to develop the GF-based linear electrode with facile fabrication process while well-maintaining satisfactory electrochemical performance. Herein, a novel Fe3O4@GF composite linear electrode is proposed via a chemical reduction-induced assembly approach, in which the GO and Fe3O4 nanoparticles (NPs) realize the efficient self-assembly owing to the electrostatic and van der Waals interactions, as well as the sufficient reduction of GO during the preparation process. The resultant fiber-shaped architecture shows boosted charge-transfer kinetics, high flexibility and structural integrity. Such Fe3O4@GF linear electrode exhibits excellent electrochemical behaviors including a large volumetric specific capacitance (∼250.75 F cm−3), remarkable rate capability and favorable electrochemical kinetics in aqueous electrolyte, superior than previously reported GF-based linear electrodes. For real application, a high-performance wire-shaped SC with excellent flexibility and weavability is fabricated based on such Fe3O4@GF linear electrode and gel electrolyte, demonstrating ultrahigh volumetric energy density (18.8 mWh cm−3), power density (4000 mW cm−3) and strong durability (∼93.5% retention after 10000 cycles). Prospectively, the fabricated wire-shaped SC can maintain reliable electrochemical behaviors in various deformation states, showing its potentials in future portable and wearable devices. [ABSTRACT FROM AUTHOR]

Directional construction of high performance carbon electrode from biomass plays a critical role in the development of energy storage devices. Herein, a straightforward and scalable route is reported to develop a cheese-like biomass-derived carbon electrode with plentiful heteroatoms for sodium-ion batteries and lithium-ion batteries by using egg white as a precursor. The resultant cheese-like structure provides more ion transport channels, shorter ion transport distance and increased charge transfer efficiency. At the same time, the self-doping by heteroatoms could offer high electronic conductivity and rich active sites. Benefited from the reasonable arrangement, the as-prepared electrode exhibits significantly enhanced sodium storage properties including highly reversible capacity (226.8 mA h g−1 at 100 mA g−1), superior rate capability and excellent capacity retention (92.8%). It also shows great lithium ion capacity (567.5 mA h g−1 after 80 cycles at 100 mA g−1), fine rate capability and outstanding capacity retention (104.8%). This work could shed light on the effective and scalable preparation of biomass-derived carbon for efficient energy storage applications. [ABSTRACT FROM AUTHOR]

Gas-atomized powders of three Fe-based glass-forming alloys were sprayed on mild steel substrates by atmospheric plasma spaying using the same spaying parameters. Microstructures, thermal stabilities and tribological properties of the sprayed coatings were analyzed. The coating performances showed a strong dependence on the intrinsic characters of the compositions, i.e., glass-forming ability (GFA) and supercooled liquid region (Δ T). The coatings tended to exhibit higher amorphous phase fraction for the composition with higher GFA and lower porosity for that with larger Δ T. All the coatings exhibited superior wear resistance compared with the substrate. Higher wear resistance could be obtained in coatings with higher amorphous phase fraction, i.e. higher GFA of the composition. This study has important implications for composition selecting and optimizing in the fabrication of metallic glass coatings. [ABSTRACT FROM AUTHOR]