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).

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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.