IET Nanodielectrics最新文献

Dielectric capacitors play an important role in advanced electronic and power systems such as portable electronic devices, hybrid electric vehicles and electronic weapon systems, and the improvement of energy storage density will have a positive effect on reducing the volume and weight of equipment. Here, a series of single-layer dielectrics with boron nitride nanosheets (BNNSs) uniformly dispersed and multilayer dielectrics with BNNSs showing a positive gradient distribution (PGD) and inverse gradient distribution (IGD) in the poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P[VDF-TrFE-CTFE]) matrix were prepared by high-speed electrospinning and hot press technology. It is found that the best performance is observed inthe lowest interlayer gradient component in both PGD and IGD composite dielectrics. However, the performance of PGD is better than that of IGD, and the 3-5-3 multilayer dielectric in the positive gradient structure has the best electrical performance. Its maximum energy storage density of the 3-5-3 composite dielectrics is 12.93 J/cm³ at the applied electric field of 380 kV/mm. The above research results show that the gradient structure design plays an important role in optimising the breakdown strength and energy storage characteristics of composite dielectrics.

Integrated energy-generating and storage films are able to convert mechanical force into stored electrical energy, with the potential for use in self-powered wearable electronics and flexible energy supplies. The development of a transparent metal salt/polyvinylidene fluoride–hexafluoropropylene composite film is reported that possesses excellent piezoelectric and dielectric properties and has the potential to be employed as an energy-generating and preserving integrated film. The effects of the type of the metal salt and its content on the dielectric properties, d₃₃ value, open circuit voltage, and holding time of the composite films were investigated. Owing to the presence of pure water, the β-phase composition and polarization of the film are increased, leading to improved energy conversion properties. Most important, the prepared film exhibits excellent light transmittance. This film, which possesses both good electrical and transparent properties, has the potential for use as a flexible energy supplier, particularly for photovoltaic devices.

Polymer dielectrics have drawn great attentions for applications in advanced electronic devices and power grids because of their high breakdown strength, low dielectric loss, and excellent flexibility. However, the low energy density in polymer dielectric capacitors will hinder the continuous miniaturization of electrical systems. In this work, ultraviolet irradiation is demonstrated to greatly enhance the breakdown strength and energy density of polypropylene. Dramatically improved breakdown strength of 867 MV/m and discharged energy density of 8.0 J/cm³, together with the high energy efficiency of >90%, were simultaneously achieved in polypropylene after ultraviolet irradiation. Our research shows that proper ultraviolet irradiation can effectively improve the energy density of polypropylene without sacrificing its high charge-discharge efficiency, being potential for applications in power electronics and pulse electric systems.

Graphene has attracted scientific interest as a substrate or additive for developing high-performance stimuli-responsive materials. Research on graphene-based polymer dielectric composites has shown an enhanced electroresponsive electrorheological (ER) effect. However, the mechanism behind the enhanced electroresponse is still incompletely understood. Here, an investigation was performed into dielectric polarization and the ER effect of reduced graphene oxide-supported polyaniline nanoplates by comparing them with pure granular polyaniline and graphene oxide-supported polyaniline nanoplates based on dielectric spectroscopy and rheologic analysis. We discovered that both anisotropic morphology and electrical properties have dominant roles in the enhanced ER effect of reduced graphene oxide-supported polyaniline nanoplates, whereas only anisotropic morphology has a dominant role in the enhanced ER effect of graphene oxide-supported polyaniline nanoplates. The analysis also showed that reduced graphene oxide-supported polyaniline nanoplates have a good ER response to both DC and AC electric field actions in the wide shear rate region. This is highly desirable for practical engineering applications. Therefore, the analysis reveals the reason for the enhanced ER effect of reduced graphene oxide-supported polyaniline nanoplates and also may provide a guide for designing high-performance ER materials for practical engineering applications by combining the advantages of conducting a reduced graphene oxide core and ER active shell.

The suitability of corn oil nanofluid as an insulation material is studied herein by analysing the partial discharge characteristics. Experiments are conducted on nano-silica modified corn oil at 0.01, 0.05, and 0.1 wt.% mass fractions. Electrode configurations are used to generate partial discharge (PD) sources such as corona discharge, internal discharge, and surface discharge. Partial discharge inception voltage dependency on electrode geometry is studied. Phase-resolved partial discharge analysis (PRPD) at various test conditions is done to understand the influence of live element geometry that causes PD in real-time operations, Weibull statistical analysis of PD parameters like scale parameter, shape parameter, skewness, and repetition rate is evaluated to understand the influence of nanofiller mass fraction in corn oil. The results illustrate that the addition of silica nanoparticles to corn oil has a significant influence on PD characteristics. The PRPD pattern analysis reveals information about the PD dependency on electrode configuration of the test condition. The addition of nanofillers in optimal concentrations without agglomeration can influence the PD characteristics to a certain degree. The test results may be inferred to suggest corn oil-based silica nanofluids as an alternative biodegradable liquid insulation.

The trend of choosing insulating materials has changed in the past few decades, and a considerable shift has occurred from conventional ceramic to non-ceramic insulating materials. The addition of inorganic fillers has greatly improved the thermal conductivity, discharge resistance, hydrophobicity recovery, and vandalism-resistance properties of polymeric insulating materials. Since the beginning of the present century, the field of nanomaterial research has gained much attention. Several studies have been conducted to investigate and analyze polymer nanocomposites by adding nanoparticles of varying size and concentration as fillers. The aim is to improve the characteristics and reformation of thermal, electrical, and mechanical properties of existing polymeric insulation materials. However, certain inconsistencies are prevalent with results obtained for polymer nanocomposites. A comprehensive review is presented based on available literature focussing on the advancement from polymeric insulating materials to polymeric nanocomposites and its impact on partial discharge resistance, surface charging, and tracking and erosion resistance. It is observed that the weight percent and dispersion of nano- or micro-sized particles into the base polymer matrix governs the performance of polymer composites. At higher filler loading, resistance to partial discharge and tracking and erosion decreases as a result of the agglomeration of fillers, whereas resistance to surface charge accumulation increases at higher filler loading because the formation of shallow traps increases the charge decay rate. It is suggested that when both micro- and nanofillers are mixed in proper proportion, micro–nano hybrid composites provide better performance than composites filled with only nano- or microfillers.

Cross-linked polyethylene (XLPE) is commonly used as an insulation material in power cables. Due to the recent advancements in the field of high voltage power transmission and distribution, there is a need for novel cable insulation materials that have high performance, recyclability and high working temperature as alternatives for the conventional XPLE-based insulation materials. Polypropylene (PP) shows excellent properties and has drawn considerable attention as a potential high voltage direct current (HVDC) insulation material. Therefore, the development of PP-based HVDC cable insulation with improved electrical, thermal and mechanical properties is important in discovering a potentially recyclable cable insulation material. Due to the remarkable development in the field of nanodielectrics, nanotechnology can be a promising solution for enhancing the overall dielectric properties of PP-based insulation materials. This review presents the important aspects of PP-based nanocomposites for HVDC cable insulation with a special focus on understanding the effects of various parameters of nanofillers on the dielectric properties of PP-based HVDC cable insulation. Based on the gathered information, future perspectives for improving the dielectric properties of PP-based nanocomposites for HVDC cable are provided.

The state of the ampere-hour capacity of the battery depends on the condition of materials used in it. Large reduction of capacity ends with maintenance or replacement of the battery. Modern battery materials include application of nanomaterials and nanotechnology in various stages of production. This article attempts to monitor the capacity of battery used for vehicles which are made of different types of materials using switching transients. The analytical part was done using wavelet-based decompositions. Data sets of large number of coefficients have been developed for learning. Their statistical behaviour has been studied, and monitoring was initially carried out by some selective parameters. Then the artificial neural network-based algorithm was developed which includes all features of statistical variation for better monitoring. Case studies have been carried out followed by comparison. The study ends with a satisfactory monitoring.

Laser texturing has been carried out on the surface of the silicone nano-micro composites to achieve super hydrophobic properties, and water droplet-initiated Corona discharge studies were carried out. The Corona inception voltage (CIV) exhibits considerable enhancement with increase in the nano filler content under DC voltage compared with AC voltage. The corona inception voltage is high with the textured surface and is found to have direct correlation with contact angle of the composite specimen. The Corona inception voltage was measured using Ultra-high frequency (UHF) and fluorescent fibre techniques. It is observed that the fluorescent fibre technique is more sensitive in identifying discharges. Frequency domain analysis of UHF signal shows a dominant frequency at 1 GHz and for fluorescent signal, the spectral content is in the range of DC to 10 MHz. The rise time and pulse width of the UHF signal increases with the increase in the nano filler in composite material. The energy content of UHF/fluorescent signal due to discharges shows similar trend with its increase in energy with variation in its magnitude of the signal formed. The pulse width of fluorescent signal formed due to water droplet-initiated discharges under AC and DC voltage is almost the same, and with the textured specimen it is quite low than the non-textured material.

Here, the nano-sized dielectrics in biosystems and their functions are reviewed. For a variety of electromagnetic phenomena observed in biosystems, from a generation of weak electrical pulses in all kinds of neural systems to generation of high-power electrical pulses for sensing and attacking preys in electric eels, nano-dielectrics, such as lipid membrane, always play an important role. The electromagnetic pulses in neural systems are created by transmembrane ionic fluxes through a cluster of ion channels embedded in a lipid membrane, but the high-power pulses released by electric eels are simultaneously generated by billions of ion channels. An overlooked function of the nano-dielectrics is that they build up a network serving as the major transmitting paths for electromagnetic pulses in dendrites and axons, and even in ordinary cell membranes. Many fundamental questions in the working mechanisms of nano-dielectrics in nature biosystems remain open and answers to these questions may lead to novel, high-efficiency manmade power supplies and a better understanding of brain functions.