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Although the performance of the self-standing electrode has been enhanced for aqueous zinc-ion batteries (AZIBs), it is necessary to explore and analyse the deep modification mechanism (especially interface effects). Herein, density functional theory (DFT) calculations are applied to investigate the high-performance cathode based on the VO2/carbon cloth composites with heterostructures interface (H-VO2@CC). The adsorption energy comparisons and electron structure analyses verify that H-VO2@CC has extra activated sites at the interface, enhanced electrical conductivity, and structural stability for achieving high-performance AZIBs due to the presence of built-in electric field at the interfaces. Accordingly, the designed self-standing H-VO2@CC cathode delivers higher rate capacity, longer-life cyclability, and faster electronic/ion transmission kinetics benefiting from the synergistic effects. The risks of active material shedding and dissolution during the dis/charge process of two cathodes were evaluated via ex-situ ultraviolet—visible (UV-vis) spectrum and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) technique. Finally, this investigation also explores the charge storage mechanism of H-VO2@CC through various ex-situ and in-situ characterization techniques. This finding can shed light on the significant potential of heterostructures interface engineering in practical applications and provide a valuable direction for the development of cathode materials for AZIBs and other metal-ion batteries. [ABSTRACT FROM AUTHOR]

Resistance element welding (REW) with a concealed rivet cover (Q235) was used to join steel-DP780 and Al-5052. The macroscopic morphology and the microstructure were observed using optical microscopy and scanning electron microscopy. The mechanical properties of the joint were also tested. The results show that the intermetallic compound (IMC) formed at the Q235/Al interface is FeAl3, while the IMCs formed at the DP780/Al interface are Fe2Al5 and FeAl3. The welding current has a significant influence on the nugget size, peak load, average hardness of aluminum heat-affected zone, and the bearing area of the aluminum plate. There are three fracture models of the countersunk rivet REW joint under a tensile-shear force: the interface failure fracture model, the fusion pullout failure fracture model, and the heat-affected zone failure fracture model. At a welding current of 18 kA, the nugget pullout failure mode is observed, and the best mechanical properties of the joint are obtained. The shear resistance of the joint can reach up to 5712 N. [ABSTRACT FROM AUTHOR]

VO2 generally has a higher theoretical capacity and layered structure suitable for the intercalation/extraction of zinc ions. However, Zn2+ ions with high charge density interact with the crystal lattice and limit further improvement in electrochemical performance. Defect engineering is a potential modification method with very promising application prospects, but the established procedures for preparing defects are complicated. In this study, VO2–x(B) with oxygen deficiency is prepared by a simple solution reaction with NaBH4. The presence of oxygen deficiencies is confirmed by positron annihilation lifetime spectroscopy, UV/Vis absorbance spectroscopy and others. Owing to the presence of oxygen defects, the aqueous Zn/VO2–x(B) battery exhibits improved specific capacity, excellent reversibility, and structural stability. Ex situ characterization techniques are employed to demonstrate the reversible insertion‐extraction mechanism of Zn2+ ions from and into the host material. In addition, the Zn/VO2–x(B) batteries still exhibit considerable electrochemical performance, even with high‐loading electrodes (about 4 mg cm−2). [ABSTRACT FROM AUTHOR]

VO 2 generally has a higher theoretical capacity and layered structure suitable for the intercalation/extraction of zinc ions. However, Zn 2+ ions with high charge density interact with the crystal lattice and limit further improvement in electrochemical performance. Defect engineering is a potential modification method with very promising application prospects, but the established procedures for preparing defects are complicated. In this study, VO 2-x (B) with oxygen deficiency is prepared by a simple solution reaction with NaBH 4 . The presence of oxygen deficiencies is confirmed by positron annihilation lifetime spectroscopy, UV/Vis absorbance spectroscopy and others. Owing to the presence of oxygen defects, the aqueous Zn/VO 2-x (B) battery exhibits improved specific capacity, excellent reversibility, and structural stability. Ex situ characterization techniques are employed to demonstrate the reversible insertion-extraction mechanism of Zn 2+ ions from and into the host material. In addition, the Zn/VO 2-x (B) batteries still exhibit considerable electrochemical performance, even with high-loading electrodes (about 4 mg cm -2 )., (© 2020 Wiley-VCH GmbH.)