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Uniform NiS 2 nanocubes are successfully synthesized with a microwave-assisted method. Interestingly, NiS 2 nanocubes, nanospheres and nanoparticles are obtained by controlling microwave reaction time. NiS 2 nanomaterials are primarily applied to supercapacitors and cocatalytic enhancing photocatalytic H 2 production. Different morphologies of NiS 2 nanostructures show different electrochemical and cocatalytic enhancing H 2 production activities. Benefited novel nanostructures, NiS 2 nanocube electrodes show a large specific capacitance (695 F g −1 at 1.25 A g −1 ) and excellent cycling performance (the retention 93.4% of initial specific capacitance after 3000 cycles). More importantly, NiS 2 nanospheres show highly cocatalytic enhancing photocatalytic for H 2 evolution, in which the photocatalytic H 2 production is up to 3400 μmol during 12 hours under irradiation of visible light (λ>420 nm) with an average H 2 production rate of 283 μmol h −1 .

Interfaces between different materials, for instance, electrode–dielectrics and vacuum/air/SF6‐insulators and oilpaper, are universal in high‐voltage insulation systems. Targeted tailoring of the interfacial properties, e.g. chemical structures, micro‐/nanoscale morphology, the charge injection barrier, trap states, and surface conductivity, is thought to be an effective approach to improve insulation properties such as breakdown and flashover strength, corona/tracking resistance, and wettability. In this article, the authors review recent progress in interface tailoring methods and their application to improve various insulation properties. The potential application scenarios of interface tailoring in different facilities are first summarised, and the desired insulation properties of various applications are highlighted. Interface tailoring methods are classified as physical/chemical surface modification and surface coating (inorganic, organic and composite), and the features of different techniques are described in detail. The structure–property relationships between interfacial states and various microscopic parameters such as charge injection barrier, trap distribution and surface conductivity are discussed together with the tailoring mechanisms for different insulation properties. Finally, the future development prospects of interface tailoring methods and their applications, e.g. multifunctional coating and stimuli–response smart coating, are presented.

Space charge accumulation in polypropylene (PP) affect the dielectric properties and breakdown strength of the material. The pre-injected charge in PP under the action of different polarity voltage is quantitatively characterized, and the effects of the pre-injected charge inside the dielectric on the dielectric properties and breakdown strength are measured and analyzed. Based on the molecular simulations, the influence mechanism of the temperature on dielectric properties and breakdown are discussed. The experimental results show that the injected charges in PP under the negative polarity voltage is significantly larger than that of the positive polarity. These charges have a great influence on the dielectric constant and breakdown performance of PP, and the effect is different for different charge polarity. The effect of negative polarity pre-voltage conditions on the dielectric constant is much greater than that of positive polarity, and the dielectric constant of PP decreases from 2.2 to 1.3, decreasing about 41% under the negative polarity pre-voltage. By contrast, the dielectric constant slightly increases under the effect of the homopolar preload. Furthermore, the breakdown strength of the dielectric after the heteropolar preload is 249 kV/mm, which is 36% lower than that of PP without pre-voltage, and it slightly increases after the positive polarity pre-voltage. As the temperature increases, the increase in free volume favors the development of electron collision ionization and electron collapse processes, leading to a decrease in breakdown voltage at high temperatures. This work has a good guiding significance for the comprehensive evaluation of energy storage parameters.

Lithium‐metal anodes suffer from inadequate rate and cycling performances for practical application mainly due to the harmful dendrite growth, especially at high currents. Herein a facile construction of the porous and robust network with thermally conductive AlN nanowires onto the commercial polypropylene separator by convenient vacuum filtration is reported. The so‐constructed AlN‐network shield provides a uniform thermal distribution to realize homogeneous Li deposition, super electrolyte‐philic channels to enhance Li‐ion transport, and also a physical barrier to resist dendrite piercing as the last fence. Consequently, the symmetric Li|Li cell presents an ultralong lifetime over 8000 h (20 mA cm−2, 3 mAh cm−2) and over 1000 h even at an unprecedented high rate (80 mA cm−2, 80 mAh cm−2), which is far surpassing the corresponding performances reported to date. The corresponding Li|LiFePO4 cell delivers a high specific capacity of 84.3 mAh g−1 at 10 C. This study demonstrates an efficient approach with great application potential toward durable and high‐power Li–metal batteries and even beyond. A porous and robust network of thermally conductive aluminum nitride (AlN) nanowires is conveniently constructed onto the commercial polypropylene separator. Such an AlN‐network shield provides the uniform thermal distribution for homogeneous Li deposition and dendrite‐free plating thereof, super electrolyte‐philic channels for fast Li‐ion transport, and also a last physical barrier to resist dendrite piercing, leading to the unprecedented cycling performance at high rate.

Five novel bis-tridentate Ir(III) complexes (Ir-1–Ir-5) incorporating versatile N^N^C ligands and a N^C^N ligand (1,3-di(2-pyridyl)-4,6-dimethylbenzene) were synthesized. With the combination of experimental and theoretical methods, their steady and transient state characteristics were researched scientifically. The UV-visible absorption spectra show that the broadband charge transfer absorbance of those bis-tridentate Ir(III) complexes can reach 550 nm, all of these complexes reveal the long-lasting phosphorescent emission. Because the excited-state absorption is more powerful than the ground-state absorption, a sturdy reverse saturable absorption (RSA) process can ensue in the visible and near-infrared regions when the complexes are exposed to a 532 nm laser. Therefore, the optical power limiting (OPL) effect follows the trend: Ir-5 > Ir-4 ≈ Ir-3 > Ir-2 > Ir-1. Generally speaking, the expansion of π-conjugation and the introduction of electron donating/withdrawing groups on the N^N^C ligand could effectively elevate the OPL effect. Therefore, these octahedral bis-tridentate Ir(III) complexes might be exploited as potential OPL materials.

A semi‐conductive shielding layer plays an important role in the uniform electric field for a high‐voltage cable. The electric‐thermal properties of the semi‐conductive layer and insulation layer directly affect the overall insulation performance of the cable. The physicochemical performances of semi‐conductive composites are firstly analysed herein. Furthermore, electric‐thermal properties of the semi‐conductive layer and insulation layer are discussed. The experimental results show that the thermal conductivity of the commercial semi‐conductive layer is about twice that of the insulation layer, owing to the effect of carbon black. The thermal expansion coefficient of the insulation layer rises from 1.86 × 10−4/K at 25°C to 3.20 × 10−4/K at 90°C. By contrast, the semi‐conductive layer begins to slowly decline at a certain temperature, and decreases significantly to 2.25 × 10−4/K at 80°C, owing to the effect of ethylene‐vinyl acetate copolymer (EVA). The electrical experiments show that the resistivity of semi‐conductive composite gradually rises with an increase in temperature, and gradually declines with an increase in the carbon black content. The dc breakdown strength of the composite structure of the semi‐conductive layer/insulation layer decreases significantly with an increase in temperature, decreasing from 307 kV/mm at 25°C to 203 kV/mm at 90°C. At four typical temperatures, the breakdown strength reaches the maximum value when the carbon black content is 25 phr. It is about 15% and 19% higher than carbon black contents of 20 and 30 phr. These findings have reference significance for high‐voltage cable breakdown fault analysis and material selection in cable design.

Four prestressed high strength concrete (PHC) piles under low-cycle loading and two piles under monotonic flexural loading were tested to study the test phenomena, failure modes, hysteretic performance, ductility and bearing capacity. It was indicated that PHC piles failed suddenly and the bearing capacity decreased because of the tensile rupturing of prestressing tendons from the results, and the hysteretic curves pinched. Nonlinear finite element models were established to analyze the mechanical properties of PHC piles using ABAQUS and OpenSees. The results obtained from the numerical analysis compared well with the experimental results. In addition, nonlinear finite element models were used to study influence of the position, pattern, number and diameter of deformed bars to the PHC piles reinforced with deformed bars (PRC piles). The analysis results showed that the deformed bars should be arranged evenly in circle direction, and the bearing capacity of PRC increased with the number and diameter of deformed bars.

The combined insulation interface of a high-voltage cable and accessories is the weakest part of a cable system. In this paper, the parameters of the dielectric constant, thermal conductivity, and elastic modulus of cross-linked polyethylene (XLPE) and silicone rubber (SIR) are obtained experimentally. On this basis, the model of a specific type of 110 kV cable and prefabricated insulation joint is established. A simulation of the electric–thermal–stress coupling field in the presence of typical defects in the main insulation–inner semi-conductive (SEMI) shielding layer (XLPE/SEMI interface) and the main insulation–silicone rubber insulation layer (XLPE/SIR interface) is studied. The simulation results show that at the XLPE/SIR interface, the electric field distortion caused by bubble defects reached 20.17 kV/mm, and the temperature rose to 56.15 °C. The effect of air-gap defects on the interface is similar to that of bubble defects. In addition, the semi-conductive impurity defects induced an increase in temperature to 56.82 °C and an increase in stress to 0.32 MPa. At the XLPE/SEMI interface, the electric field distortion induced by bubble defects was 19.98 kV/mm, and the temperature rose to 61.72 °C. The electric field distortion caused by metallic and semi-conductive defects was 8.44 kV/mm and 8.64 kV/mm, respectively. This study serves as a reference for the fault analysis and the operation and maintenance of cable accessories.

Surface discharge is a typical fault type in electric power equipment. High temperature in long‐term operation can easily lead to ageing of materials, resulting in changes in surface characteristics and surface discharge faults. In this paper, a method of surface discharge identification of silicon rubber (SiR) based on spectral detection technology is presented. The surface discharge spectral characteristics of SiR with different ageing degrees are investigated, and the changes of microphysical and chemical properties and surface insulation properties caused by thermal ageing are analysed. The dynamic evolution of charge during surface discharge is simulated. The experimental results show that the spectral intensity of the surface discharge of the SiR material is mainly concentrated at 350, 600 and 750–900 nm bands. The spectral intensity reaches the maximum value when the ageing time is 168 h. With the intensification of ageing, no new characteristic peaks generate in the discharge spectrum, but the proportion of the same characteristic peaks to the overall wavelength is different. The type of discharge material and ageing state are determined by the characteristic light intensity ratio I b . The evolutionary mechanism of the discharge spectrum is revealed by the variation of flashover voltage, trap charge density, resistivity and other parameters. The simulation results show that the increase of electron density will lead to more intense electron collision, which will release more photons, resulting in enhanced spectral intensity. This work can provide a reference for the detection of surface discharge and the evaluation of ageing state of the equipment inside the high voltage box.

The semi‐conductive shielding layer is an important part of the high‐voltage cable, playing a role in uniform electric field and reducing the air gap at the interface. The overall performance of the cable is affected by the semi‐conductive shielding layer with different base resin composition. The matrix resins of ethylene‐vinyl acetate (EVA), ethylene‐ethyl acrylate (EEA) and ethylene‐butyl acrylate (EBA) were used to prepare the semi‐conductive shielding materials of CB/EVA, CB/EEA and CB/EBA. The influences of different matrix resins on the chemical, electrical, thermal and mechanical properties of the shielding materials were investigated. The results show that CB has the best dispersion in EBA resin and the worst dispersion in EEA resin. The temperature inflection points of CB/EVA, CB/EEA and CB/EBA shielding materials are 90°C, 100°C and 110°C, respectively, and the CB/EBA shielding material has the lowest resistivity and the weakest positive temperature coefficient effect at room temperature. The thermal conductivity of all three matrix resins is smaller than that of the shielding material, the thermal conductivity of CB/EVA and CB/EBA shielding materials show a slow increase with temperature, and the CB/EEA shielding material is the least affected by the temperature. The mechanical properties of the three matrix resins and the three shielding materials are EBA > EVA > EEA, among them the stress of CB/EBA shielding material is 31.0 MPa and the strain is 570%. This work has important reference significance for the selection of shielding layer matrix resin and material formulation in engineering applications.