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The type of matrix resin of the semi‐conductive shielding layer directly affects the thermal aging characteristics of the semi‐conductive shielding layer and the high‐voltage cable. In this paper, ethylene vinyl acetate (EVA), ethylene ethyl acrylate (EEA), and ethylene butyl acrylate (EBA) resins were used as matrix to prepare carbon black (CB) + EVA, CB + EEA, and CB + EBA shielding materials. The law of physicochemical, electrical, and mechanical properties of different matrix resin shielding materials with aging time was studied, and the influence mechanism of matrix resin on the aging characteristics of shielding materials was analyzed. The results show: with the increase of aging time, the crystallization area and the number of functional groups of the three shielding materials decreased to varying degrees. The number of functional groups in CB + EBA shielding materials decreased evenly with aging time, but that of CB + EVA and CB + EEA shielding materials changed significantly after 7 days of aging. After 60 days of aging, the crystallization area of CB + EBA shielding material changed slightly, but that of CB + EVA and CB + EEA shielding material decrease significantly. The electrical properties of the three shielding materials showed different decreasing trend with aging time. When the aging time is 7 days, the positive temperature coefficient (PTC) effect of CB + EEA shielding material decreases obviously. When the aging time is 30 days, the resistivity of CB + EVA and CB + EEA shielding material increases slowly (9 Ω cm–12 Ω cm) with the increase of temperature. When the aging time is 60 days, the resistivity of CB + EBA shielding material decreases obviously, and the PTC effect weakens obviously. Taking the mechanical properties of the shielding material as reference, the rapid deterioration stage of the mechanical properties of the three shielding materials is different. The CB + EVA and CB + EEA shielding material rapid deterioration time is 0–7 days, and the tensile strength and elongation of the shielding material are greatly reduced. The rapid deterioration stage of CB + EBA shielding material is 7–30 days, and the tensile strength and elongation decrease from 24.38 MPa and 499.5% to 14 MPa and 155.7%, respectively. This work can provide data support for the selection of matrix resin of shielding material and the fault analysis of shielding layer of high voltage cable. [ABSTRACT FROM AUTHOR]

Developing multicomponent composite materials with delicate morphology and tailored structure is of vital importance for designing advanced sodium‐ion batteries (SIBs). Herein, a confinement‐structured Fe2Mo3O8@C@MoS2 with local‐expanded interlayer spacing is designed via high‐temperature phase transition from FeMoO4 to Fe2Mo3O8 and the tactically introducing dopamine molecules into the interlayer of MoS2 nanosheets. By analysis of the in situ generated solid electrolyte interphase film in different electrolytes, the favorable compatibility of Fe2Mo3O8@C@MoS2 in ether‐based electrolytes is well illustrated. Importantly, the sodium storage mechanism and detailed structural evolution of Fe2Mo3O8 are established for the first time by in situ X‐ray diffraction. Furthermore, theoretical calculations indicate the unique structure facilitates internal charge transfer and enhances Na+ adsorption ability. Thanks to the unique confinement structure, local‐expanded interlayers and robust framework, the Fe2Mo3O8@C@MoS2 composite achieves a high reversible specific capacity of 636 mAh g‒1 at 0.1 A g‒1, excellent rate capability (301 mAh g‒1 at 5.0 A g‒1) and ultralong cycling stability (365 mAh g–1 after 6000 cycles at 2.0 A g–1). The study provides an essential understanding of the Na storage mechanism of Fe2Mo3O8 and a promising strategy for constructing high‐performance anodes for SIBs. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) becomes a superior candidate material for new environmentally friendly cable main insulation with its excellent heat resistance, electrical properties, and degradability. However, in practical application, PP material is aging and vulnerable and its toughness is poor. The mechanical properties of PP material can be improved by elastomer modification, but the effects of different elastomers on the comprehensive properties of composite specimens are quite different. In this paper, the electrical and mechanical properties of different types of elastomer‐modified PP composites are compared and analyzed by combining experimental and molecular simulation (MS) methods. The experimental results show that the SEBS/PP composite material has the lowest trap energy levels among all kinds of composite materials, its space charge accumulation is 1.96 × 10−9C, and the mechanical and rheological properties improvement of the composite is the most remarkable. Meanwhile, the volume resistivity is reduced by two orders of magnitude compared with pure PP. However, the breakdown strength of all kinds of composite materials decreases by different degrees after the modification. The solubility parameters (δ) and the free volume are further investigated by the molecular simulation, which shows that the δ of SEBS is similar to that of PP, which represents the best compatibility. Moreover, the SEBS/PP composite material has the strongest inter‐molecular force and the most excellent toughness improvement for PP. This work provides a theoretical basis for elastomer selection in PP modification. [ABSTRACT FROM AUTHOR]

Limited by sluggish reaction kinetics, insufficient electrode utilization and severe volume deformation, designing nickel‐based materials with high capacity and rate capability is still a challenge. Herein, a carbon nanotubes threaded NiSe2/Co3Se4 quantum dots embedded in carbon nanospheres with rich Se vacancies both in NiSe2 and Co3Se4 is elaborately designed via MOF template method. The formation mechanism of the Se vacancies is elucidated for the first time, which is ascribed to the release of gas during the decomposition of organic ligand inhibits the ordered arrangement of atoms. The CNT‐V‐NiCoSe possesses many significant superiorities, such as sufficiently exposed active sites, high electrode utilization, favorable charge‐carrier migration, and relaxed structure deformation. Consequently, the CNT‐V‐NiCoSe electrode shows top‐level specific capacity (384 mAh g−1 at 1 A g−1), ultrahigh rate capability (209 mAh g−1 at 150 A g−1) and remarkable cycling durability. The CNT‐V‐NiCoSe//Zn battery achieves maximum energy density of 615.6 Wh kg−1 and maximum power density of 81.7 kW kg−1. Density functional theory calculations elucidate the Se vacancies improve the density of states at Fermi level, facilitates internal charge transfer, and enhances OH− adsorption ability. This study provides guidance for the preparation of high‐performance electrode materials with rich vacancies by template method. [ABSTRACT FROM AUTHOR]

Semiconductive shielding layer as an important part of high‐voltage cable, its performance directly affects the safe operation and the service life of the cable. Carbon black (CB) is the main conductive filler of shielding materials, and its type and concentration directly affect the performance of the shielding layer. In this paper, CB‐A with higher structure and CB‐B with lower structure were used as conductive fillers and EBA was chosen as the matrix resin to prepare the shielding materials. The CB concentrations of the shielding materials were 35, 45, and 55 phr. The influences of CB type and concentration on the physicochemical, electrical, thermal and mechanical properties of the shielding materials were investigated. The research shows that when the CB types are the same, the higher the concentration of CB, the more intensive the CB network in the shielding material, and the more serious the CB agglomeration phenomenon. With increasing CB concentration, shielding materials show a decreasing trend of volume resistivity, an increasing trend of thermal conductivity, and a decreasing trend of mechanical properties. When the CB concentration is the equal, the CB‐A has better dispersion in the matrix resin, CB‐A/EBA shielding material has lower volume resistivity and weaker PTC effect, CB‐A/EBA shielding material has higher thermal conductivity at low temperature and CB‐B/EBA shielding material has higher thermal conductivity at high temperature, CB‐A/EBA shielding material has better mechanical properties. A comprehensive comparison shows that CB‐A/EBA shielding material with a concentration of 45 phr has excellent overall performance, with volume resistivity of 15.3 and 68 Ω·cm at 25°C and 90°C, respectively. The thermal conductivity is 0.434 W/(m K) at room temperature and 0.536 W/(m K) at 90°C. The stress is 31.08 MPa and the strain is 570.2%. This work has important reference for the selection of conductive fillers and performance improvement of semiconductive shielding materials. [ABSTRACT FROM AUTHOR]

With the rapid development of offshore wind power, large‐capacity wind turbine generators have put forward higher electrical and mechanical performance requirements for the cable. In this paper, kaolin/ethylene propylene diene monomer (EPDM) composites are prepared to investigate the effect of kaolin content on the electrical properties, mechanical properties and thermal conductivity of EPDM composites. The results show that appropriate amount of kaolin could synergistically improve the electrical‐thermal‐mechanical properties of EPDM. The composite with 30 wt% kaolin content achieves the best performance. The breakdown strength of kaolin/EPDM composites increases by 13.47%–72.19 kV/mm compared with that before modification, and the volume resistivity increases from 1013 to 1015 Ω·cm after modification. In addition, with the doping of kaolin, the tensile strength of composites significantly improves by over 500%–6.97 MPa, and the thermal conductivity of the composite is slightly improved. This work has important guiding significance for the development of insulation materials for cables. Highlights: Kaolin in EPDM scattered more uniform after modification.The addition of kaolin improves the electrical‐thermal‐mechanical properties of the composite.Kaolin/EPDM composites have promising applications. [ABSTRACT FROM AUTHOR]

With the concept of environmental protection is deeply popular, the power cables change from traditional thermosetting cross‐linked polyethylene (XLPE) cables to low‐carbon, environmentally friendly, recyclable polypropylene (PP) cables and the semi‐conductive shielding layer that matches the insulation layer for PP cables is highly valued. In this paper, LDPE is replaced with PP in the formulation of shielding layer of commercial XLPE cables. The physicochemical and electrical properties of PP/EVA/CB (PP‐based) and LDPE/EVA/CB (LDPE‐based) shielding layers were compared. The effect of interface matching characteristics on the electric field distortion was analyzed by finite element simulation software. The experimental results show that the volume resistivity of the shielding layers all tend to rise with the increasing temperature, but the resistivity of the PP‐based shielding layer has a smaller fluctuation. The PP‐based shielding layer has a smoother surface, while the space charge injected into the PP insulation layer is the lowest, about 0.433 × 10−7 C. Compared to the LDPE‐based shielding layer/insulation layer, the PP‐based shielding layer/insulation layer has a 50% reduction in interfacial electric field distortion rate. This work is an essential reference for the development for PP cables and their shielding layer selection. [ABSTRACT FROM AUTHOR]

Space charge accumulation in the cable insulation will cause local electric field distortion, and accelerate the aging of the material. The inner semi‐conductive layer as an important structure of cable will affect the charge injection characteristics in the insulation layer. This work intended to explore the method of modifying the semi‐conductive layer with the Nitrogen‐doped graphene (NG) to suppress the charge accumulation utilizing the super‐smoothness of graphene and electron adsorption of N element. First, the NG is prepared using N‐modified graphene, and the semi‐conductive layer with different NG content is fabricated. Second, the physical and chemical properties of the semi‐conductive composite are carried out, then the charge accumulation characteristics in the insulation layer under the effect of the semi‐conductive layer are characterized. The results showed that an appropriate amount of NG doping can significantly inhibit the charge accumulation in the insulation layer. The surface roughness decreased by about 32.13% when the doped NG content is 0.5 phr. With the increase of NG content from 0 to 1 phr, the accumulation charges inside the insulation layer decreased by about 36.84%. This research provided a new approach for suppressing space charge accumulation in the insulation material of high voltage cable. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Nanocomposite dielectric is considered the most promising insulation material for high‐voltage direct current cables. Herein, boron nitride nanoparticles (BNNPs) and boron nitride nanosheets (BNNSs) are used as nanofillers to study the effect of nanofiller concentration and morphology on the electrical properties of cross‐linked polyethylene (XLPE) composite based on experiments and simulation. The experimental results indicate that nanofiller concentration has a great influence on permittivity, while the influence of the morphology at the same concentration is small. The maximum relative permittivity occurs at 1 wt%. They are 2.35 and 2.32, respectively, for XLPE/BNNSs and XLPE/BNNP, increasing by about 11% and 9% than that of XLPE matrix. The morphology of BN significantly influence the breakdown performance, and the breakdown strength of the nanocomposite increases first and then decreases with the increase in doping concentration. The maximum breakdown strength of the composite occurs at 0.5 wt%. They are 403.8 and 349.2 kV mm−1, respectively, for XLPE/BNNSs and XLPE/BNNP, which is about 33% and 13% higher than that of XLPE matrix. Molecular simulations show that the free volume of XLPE/BNNSs is lower than that of XLPE/BNNP. In addition, the sheet structure can effectively block the carrier transport and prolong the discharge path. [ABSTRACT FROM AUTHOR]

Nickel phosphite (Ni11(HPO3)8(OH)6) superstructures assembled by nanotubes are synthesized under mild hydrothermal conditions with the sodium salt of polystyrene sulfonic acid. More importantly, Ni11(HPO3)8(OH)6 superstructures are applied as electrode materials for supercapacitors. Benefitting from their novel superstructures, in a three-electrode system, Ni11(HPO3)8(OH)6 superstructure electrodes show a good specific capacitance (1876 F g−1 at 0.625 A g−1), good rate capability, and excellent cycling properties (95 % of the initial specific capacitance at 6.25 A g−1 after 2000 cycles) in 3.0 M KOH. Additionally, asymmetric Ni11(HPO3)8(OH)6-graphene nanosheet supercapacitors are also designed. The specific energy of a cell in 3.0 M KOH reaches about 28.6 Wh kg−1 at 92.5 W kg−1. [ABSTRACT FROM AUTHOR]