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Abstract Dielectric elastomers, used as driver modules, require high power density to enable fast movement and efficient work of soft robots. Polyacrylate elastomers usually suffer from low power density under low electric fields due to limited response frequency. Here, we propose a bimodal network polyacrylate dielectric elastomer which breaks the intrinsic coupling relationship between dielectric and mechanical properties, featuring relatively high dielectric constant, low Young’s modulus, and wide driving frequency bandwidth (~200 Hz) like silicones. Therefore, an ultrahigh power density (154 W kg−1@20 MV m−1, 200 Hz) is realized at low electric field and high resonance frequency, 75 times greater than at 10 Hz. Further, a rotary motor is developed, reaching an impressive speed of 1245 rpm at 19.6 MV m−1 and 125 Hz, surpassing previous acrylate-based motors and entering the high-speed domain of silicone-based motors. These findings offer a versatile strategy to fabricate high-power-density dielectric elastomers for low-electric-field soft actuators.

Abstract With a large number of film capacitors being deployed in critical locations in electrical and electronic systems, artificial intelligence (AI) technology is also expected to address the problems encountered in this process. According to our findings, AI applications can cover the entire lifecycle of film capacitors. However, the AI safety hazards in these applications have not received the attention they deserve. To meet this, the authors argue, with specific examples, risks that flawed, erratic, and unethical AI can introduce in the design, operation, and evaluation of film capacitors. Human‐AI common impact and more multi‐dimensional evaluation for AI are proposed to better cope with unknown, ambiguity, and known risks brought from AI in film capacitors now and in the future.

Abstract Film capacitors are playing an increasingly important role in power‐related fields, driven by the continuous development of dielectric materials and practical needs. Long‐term accumulation has also led to an increasing wealth of data related to film capacitors. Sonification opens up a new way for people to make good use of data from film capacitors. A framework for sonifying film capacitors data based on TwoTone is presented. Based on the analysis and discussion, it is clear that the sonification results can easily represent the monotonic variation pattern of film capacitors data. What's more, the sonification results increase the possibility that people pay attention to the changing trend of film capacitors data when there is no significant difference in the visual perception of the data. In addition to providing a new way of music generation of electrical equipment, the method proposed is expected to contribute to theory reference in typical scenarios, such as factory calibration of film capacitors, monitoring of film capacitor operation status, and presentation of statistical data of film capacitors' dielectric materials, which will help us to better understand the distribution characteristics of polymer films.

Abstract The significant progresses of polymer‐based nanocomposites with improved dielectric performances are urgently calling for an effect way to realise commercial production. Up to now, the biaxial stretching technology is still a powerful method to produce the high‐performance dielectric films applied in the film capacitors due to its full‐blown applications. In this work, a classical composite system of BaTiO3/polypropylene was applied to reveal the connection between the microstructure changes and dielectric properties of the corresponding nanocomposite films in the biaxial stretching process. The permittivity of BT‐30 wt% nanocomposite reached 2.8 at 103 Hz after stretching, and its breakdown strength reached 340 MV/m. In addition, the breakdown strength of BT‐10 wt% nanocomposite could even be promoted to 452 MV/m, which was 1.3 times higher than that before stretching. The microstructure test demonstrated that the rearrangement of nanofillers, high crystallinity and the oriented polypropylene crystals were advantageous to the improvement of breakdown strength for the stretched nanocomposite films. Therefore, the application of biaxial stretching technology into the preparation of nanocomposite dielectric film is an enormous potential way for the energy storage film capacitors.

Highlights A bilayer dielectric film is prepared via coating boron nitride nanosheets (BNNSs) by solution casting on the surface of polyethylene terephthalate (PET) film. The BNNS layer acts as the efficient barrier layer to suppress the charge injection, thereby making the surface-modified PET films exhibit excellent breakdown strength and electrostatic energy storage performance. The surface coating methods are accessible and suitable for large-scale roll-to-roll process production of dielectric films.

Abstract Polymer dielectrics are insulators or energy storage materials widely used in electrical and electronic devices. Polymer dielectrics are needed with outstanding dielectric characteristics than current technologies. In this study, the self-assembly of boron nitride nanosheets (BNNSs) was applied to form an inorganic–organic nanocoating on various common polymer dielectrics. It is inexpensive and easy to fabricate this thin coating on a large scale. The coating has a wide bandgap and thus can significantly improve the breakdown strength of polymer dielectrics. The charge characteristics and trapping parameters of nano-domains on the surfaces of polymer dielectrics were measured, and the coating had shallow trap levels. This facilitated the dissipation of surface charges and thus greatly increased the flashover voltage. The coating also effectively improved the temperature stability and dielectric constant of the polymer dielectric. This nanocoating shows potential as a method to effectively improve the dielectric characteristics of polymer dielectrics and outperform existing composite polymer dielectrics, which are crucial for large-scale applications in energy storage and power and electronic devices.

The relative permittivity is one of the essential parameters determines the physical polarization behaviors of the nanocomposite dielectrics in many applications, particularly for capacitive energy storage. Predicting the relative permittivity of particle/polymer nanocomposites from the microstructure is of great significance. However, the classical effective medium theory and physics-based numerical calculation represented by finite element method are time-consuming and cumbersome for complex structures and nonlinear problem. The work explores a novel architecture combining the convolutional neural network (ConvNet) and finite element method (FEM) to predict the relative permittivity of nanocomposite dielectrics with incorporated barium titanite (BT) particles in polyvinylidene fluoride (PVDF) matrix. The ConvNet was trained and evaluated on big datasets with 14266 training data and 3514 testing data generated form a programmatic algorithm. Through numerical experiments, we demonstrate that the trained network can efficiently provide an accurate agreement between the ConvNet model and FEM by virtue of the significant evaluation metrics R2, which reaches as high as 0.9783 and 0.9375 on training and testing data, respectively. The strong universality of the presented method allows for an extension to fast and accurately predict other properties of the nanocomposite dielectrics.

Flexible transparent conductive films are gaining attention day by day over the last few years due to it is a key component of next generation flexible electronics and optoelectronic devices. Indium tin oxide (ITO) as one of the most widely used transparent conductive material is limited by the traditional deposition approach cannot be achieve ultra-thin, which results in its brittle nature. Herein, a novel strategy for fabricating highly transparent conductive films by liquid metal interface phase separation technique based on low-melting liquid metal of InxSn100-x alloy is reported, during the solid-to-liquid phase transition of alloy, the monolayer of surface oxide film segregated with the bulk phase and was printed on the flexible polyethylene-naphthalate (PEN) substrate under the van der Waals. This novel strategy can directly print the ultra-thin self-oxide with the structure of ITO on PEN substrate, with the resulting of transparency over 97.5% and resistivity as low as 0.21 kΩ cm, providing a new way of low-cost raw ITO material as well as the personalized preparation strategy. The desirable highly transparent conductive films are comparable to recently reported ITO film, together with advantages of pretty steady, make them attractive as various flexible transparent conductive electrodes, for example, an ultra-thin ITO film is developed for luminescent devices.

Abstract Large deformability and high sensitivity is difficult to be realized simultaneously in flexible sensors. Herein, taking advantage of the high permittivity and highly active surfaces of the ultrasmall barium titanate nanoparticles (BT NPs) and the high stretchability of the p(BA‐GMA) elastomer matrix, we propose a high‐performance soft stretchable sensor. The addition of the ultrasmall BT NPs can not only increase the permittivity and capacitance of polyacrylate‐matrix composite dielectric material to obtain a high sensitivity, but also basically maintains the excellent mechanical properties of the polymer matrix. The dielectric constants of the composite films increase from 5.68 to 13.13 at 10 kHz with the increase of BT NPs content from 0 to 15 vol.%, which results in a high capacitance of 236.16 pF for 15 vol.% BT/p(BA‐GMA) sensor. Combining the high permittivity and the large deformability (a maximal deformation of 87.2%), the 15 vol.% BT/p(BA‐GMA) sensor has high sensitivity and shows high linearity and stable output even if under dynamic measurement. The dual‐mode sensor that utilizes the orthogonality of capacitance‐resistance is designed, which shows excellent performance in monitoring human body movements and noncontact measurement. The results present that the BT/p(BA‐GMA)‐based sensor has high stability and reliability not exceed 65°C, which can meet the application requirements in dynamic monitoring.

Abstract Al electrodes with different thickness (sheet resistance 2–100 Ω/□) were deposited onto the films of polypropylene (PP), polyester (PET) and polyimide (PI) by vacuum evaporation. The root‐mean‐square (RMS) and peak‐to‐valley roughness of Al electrodes were characterised by atomic force microscopy (AFM). It was found that the PET and PI substrates showed the reduced threshold thickness of the continuous growth of Al electrodes compared with the PP substrate. The sheet resistance of Al electrodes decreases with the increase of peak‐to‐valley roughness. The current surge capability of the Al electrode decreases with the increase of RMS roughness. The Al electrode deposited on the PET film has higher sheet resistance and better current carrying capability, and the self‐healing performance of metallised film is also excellent among three kinds of films.

Polymers and composites with high thermal conductivity are promising yet challenging for the growing demand of thermal management in electrical and electronic equipment. Guided by the closest packing model, a multiscale filling Al2O3 strategy was designed and incorporated with epoxy resin (EP) to form high thermal conductive composites in this work. Epoxy composites with single filler loading were also prepared. The microstructures, thermal, rheological, and dielectric characteristics of the multiscale filling Al2O3/EP composites have been investigated. Compared with single-scale Al2O3 filled epoxy based composites, it is found that the multiscale filling Al2O3/EP composites exhibit higher thermal conductivity under the same filler loading of 50 vol %, which is attributed to the efficient heat conduction paths formed by appropriate multiscale fillers. Particularly, a remarkably improved thermal conductivity of 2.707 W m−1 K−1 was acquired in Al2O3/EP composites at filler loading of 50 vol% (5 μm Al2O3 (26.67 vol%), 30 μm Al2O3 (27.41 vol%) and 70 μm Al2O3 (45.92 vol%)), which is about 1300% higher than that of the pure epoxy resin. In addition, the dielectric constant of the Al2O3/EP composites were significantly improved while keeping the dielectric loss almost unchanged. The finite element simulation further verified the effectiveness of improving the thermal conductivity of materials in the heat dissipation of electrical equipment. Therefore, this research provides a simple strategy for manufacturing high thermal conductive composite materials with a wide range of potential applications as packaging materials.

Abstract Most commonly used dielectric elastomers (DEs) such as acrylic dielectric elastomers VHBTM 4910 need a high actuation voltage and pre‐stretching to obtain a large actuation strain, and present high mechanical loss caused by viscoelasticity. In this work, we fabricated a new acrylic elastomer by UV curing based on CN9021 and lauryl acrylate. By manipulating crosslinker content, crosslink density changed and physical entanglements of the new material can be affected. Therefore, mechanical properties such as Young's Modulus and mechanical loss of the new material can be controlled, and little change of its glass transition temperature was induced. Results of the actuation test show that the new DE is capable of 9.0% actuation area strain under 11 kV/mm and a good performance under oscillating voltage with different waveforms and frequencies.

Abstract Polymer‐based dielectrics are extensively applied in various electrical and electronic devices such as capacitors, power transmission cables and microchips, in which a variety of distinct performances such as the dielectric and thermal properties are desired. To fulfil these properties, the emerging machine learning (ML) technique has been used to establish a surrogate model for the structure–property linkage analysis, which provides an effective tool for the rational design of the chemical and morphological structure of polymers/nanocomposites. In this article, the authors reviewed the recent progress in the ML algorithms and their applications in the rational design of polymer‐based dielectrics. The main routes for collecting training data including online libraries, experiments and high‐throughput computations are first summarized. The fingerprints charactering the microstructures of polymers/nanocomposites are presented, followed by the illustration of ML models to establish a mapping between the fingerprinted input and the target properties. Further, inverse design methods such as evolution searching strategies and generative models are described, which are exploited to accelerate the discovery of new polymer‐based dielectrics. Moreover, structure–property linkage analysis techniques such as Pearson correlation calculation, decision‐tree‐based methods and interpretable neural networks are summarized to identify the key features affecting the target properties. The future development prospects of the ML‐driven design method for polymer‐based dielectrics are also presented in this review.

Metallized Film Capacitors (MFC) are vital devices in many important fields such as energy, transportation, and aviation, whilst Digital Twin (DT) technology opens a new channel to leverage existing data resources of metallized film capacitors. This paper review current knowledge about metallized film capacitors and digital twin, list the key issues, propose frameworks, and provide the outlook to clarify the potential of digital twin’s application in metallized film capacitors. First, based on the development history and research status of metallized film capacitors, this review sorts out the key research issues of data utilization. Then, the connotation and typical characteristics of the digital twin definition are combed and refined, and the typical architecture of digital twin implementation is presented. Furthermore, the overall application architecture of digital twin in metallized film capacitors is constructed, and the technology system of each application scenario and the role of digital twin are analyzed. Finally, the main challenges in the application of the digital twin in metallized film capacitors and the future development directions are discussed. This review promotes the performance improvement, cost reduction and application expansion of metallized film capacitors, which can be used as a guide for the application of digital twin in other power equipment of energy system.

Dielectric elastomer actuators (DEAs) with large electrically actuated strain can be used in non-magnetic motors, but high stiffness, poor strength and slow response currently limit the application of DEAs. Here, the authors optimize the crosslinking network in a polyacrylate elastomer to enable a DEA with high toughness and actuation strain and use the polyacrylate to build a motor which can be driven under low electric field.

Abstract The synthesis of core@double‐shells structured TiO2@C@SiO2 nanowires (NWs) with variable thickness of carbon inner shell and SiO2 outer shell was achieved by individually controlling the chemical vapour deposition time and amount of silicon precursor added in the sol–gel synthesis. The resultant TiO2@C@SiO2 NWs filled nanocomposites exhibited an excellent dielectric performance with simultaneously improved dielectric constant and suppressed dielectric loss, which could be further regulated by individually controlling the carbon inner shell and SiO2 outer shell thickness. More importantly, the influences of the conductive carbon inner shell and insulated SiO2 outer shell thickness on the dielectric performance of nanocomposites were clearly revealed. The increase of the conductive carbon inner shell thickness would lead to an increase in dielectric constant and loss of nanocomposites, while the insulated SiO2 outer shell exhibited a totally opposite law that the dielectric constant and loss of nanocomposites decrease with increasing SiO2 outer shell thickness. Numerical simulations were also carried out to theoretically verify the relationship between the dielectric loss and SiO2 outer shell thickness. This promising controllable multi‐shell structure could be extended to a variety of hybrids to develop high‐performance dielectric nanocomposites.

Abstract Polymer nanocomposites have attracted increased attention for use in the field of high‐voltage direct current (HVDC) cable insulation. To study the use of polymer nanocomposites for this purpose, 3D flower‐like MgO (flower‐MgO) particles with hierarchical surface morphology are first synthesised. Polypropylene (PP) was simultaneously mixed with styrene‐(ethylene‐co‐butylene)‐styrene triblock copolymer (SEBS) and flower‐MgO to obtain PP/SEBS/flower‐MgO composites. The microstructural, thermal, electrical, and mechanical properties of the obtained nanocomposites were then studied in detail. The results showed that flower‐MgO particles loaded at low concentration were well dispersed in the PP/SEBS matrix. The incorporation of flower‐MgO particles has been found to significantly suppress the injection of homocharges and strengthen the ability to release the charge, thus containing accumulation of the space charge. The DC breakdown strength of PP/SEBS/flower‐MgO composites was increased to 323 MV/m. Meanwhile, the tensile strength and elongation at break of the obtained composites was improved by loading 0.5 phr flower‐MgO because of the synergistic toughening effects of SEBS and MgO. The investigation demonstrates the immense potential to replace nonrecyclable cross‐linked polyethylene as an HVDC cable insulating material.

High-performance epoxy (EP) composites with excellent thermal conductivity and dielectric properties have attracted increasing attention for effective thermal management. In this work, three-dimensional (3D) structural functional fillers were prepared by an electrostatic self-assembly approach. The negatively charged carbon nanotubes (nCNTs) prepared by carboxylation on the surface of CNTs were attached to the positively charged boron nitride (pBN) to form the 3D pBN@nCNTs functional fillers. The morphological characterizations of the formed 3D pBN@nCNTs fillers and epoxy composites were established, illustrating that nCNTs were linearly overlapped between the BN sheets, thus forming a 3D heat conduction network in the epoxy matrix. The synergistic effect of pBN with nCNTs on the enhancement of thermal conductivity and dielectric properties of composites was systematically studied. The experimental results demonstrated that the thermal conductivity of pBN@nCNTs/EP composites could reach 1.986 W m−1K−1 with the loading of 50 wt% fillers at 10:1 mass ratio of pBN:nCNTs, which is 464% and 124% higher than that of pure EP and BN/EP, respectively. Simultaneously, the dielectric permittivity was successfully increased to 15.14. Moreover, the thermal stability of the composites was synchronously enhanced. This study provides a facile path to fabricate thermosetting polymer composites with high thermal conductivity and dielectric properties.

Abstract Polymers are widely used as dielectric components and electrical insulations in modern electronic devices and power systems in the industrial sector, transportation, and large appliances, among others, where electrical damage of the materials is one of the major factors threatening the reliability and service lifetime. Self‐healing dielectric polymers, an emerging category of materials capable of recovering dielectric and insulating properties after electrical damage, are of promise to address this issue. This paper aims at summarizing the recent progress in the design and synthesis of self‐healing dielectric polymers. The current understanding to the process of electrical degradation and damage in dielectric polymers is first introduced and the critical requirements in the self‐healing of electrical damage are proposed. Then the feasibility of using self‐healing strategies designed for repairing mechanical damage in the healing of electrical damage is evaluated, based on which the challenges and bottleneck issues are pointed out. The emerging self‐healing methods specifically designed for healing electrical damage are highlighted and some useful mechanisms for developing novel self‐healing dielectric polymers are proposed. It is concluded by providing a brief outlook and some potential directions in the future development toward practical applications in electronics and the electric power industry.

Electroactive polymer (EAP) is a kind of smart material, which can change its shape under the stimulation of electric field. Dielectric elastomer (DE) is an important member of the EAP. DE has the characteristics of excellent performance, such as light weight, low noise, low cost, and so on, which guarantee its wide applications in the fields of actuators, generators, sensors. In this review, the principles of energy conversion, the research status and latest development of new technologies for DEs, and the performance characteristics of DEs are summarised. Simultaneously, it points out the development problems and feasible countermeasures. At last, the application prospects of DE are discussed, combined with the research direction of the international frontier.

Polymer nanocomposites with improved dielectric permittivity and high breakdown strength are extremely desirable for the flexible electronic devices and power systems. The compatibility of fillers and polymer matrix is important in determining the dielectric and breakdown strength properties. The core–shell structure concept is useful to improve the compatibility of fillers with polymer matrix. Herein, an organic thermoplastic urethanes (TPU) polymer shell was successfully grafted on the surface of barium titanate (BaTiO(3), BT) and such a TPU shell improved the permittivity and breakdown strength of TPU@BT/PVDF polymer nanocomposites greatly. The permittivity of TPU@BT/PVDF nanocomposites with 12 wt% fillers at 10^2 Hz was up to 13.5, which was 1.5 times higher than that of pure poly(vinylidene fluoride) (PVDF). The improvement of the dielectric properties could be attributed to the enhanced interfacial polarisation between BT nanoparticles and TPU shell. Besides, the compatibility of BT nanoparticles and PVDF matrix was improved after the introduction of TPU shell. Accordingly, a highest breakdown strength value about 373 MV/m was obtained for the TPU@BT/PVDF nanocomposites with 7 wt% fillers. The core–shell strategy could be extended to a variety of inorganic fillers to improve the dielectric and breakdown strength properties of polymer nanocomposites.

Polymer-based composites with ceramic fillers could combine the advantages of both, which can be potentially used in electrical and electronic technology. In this work, the barium titanate (BaTiO(3)) nanofibres and the core–shell structured BaTiO(3)@Al(2)O(3) nanofibres with Al(2)O(3) insulation layer coated on the BaTiO(3) surface were both prepared via the electrospinning method. The appropriate incorporation of the ceramic nanofibres effectively improves the dielectric properties and energy density of the polymer. Moreover, the poly(vinylidene fluoride-co-hexafluoropropylene)-based composite films with the three-layer sandwich structure were fabricated to further promote the dielectric properties. The results show that the outer two layers with a higher content of BaTiO(3) nanofibres can make more contribution to the improved permittivity of the composites. In addition, the introduction of the interlayer with low loading of BaTiO(3)@Al(2)O(3) nanofibres promotes the breakdown strength. This work gives rise to the potential in high energy storage applications.

Flexible polymer-matrix nanodielectrics have recently been attracting more attention in the fields of frontier research internationally since the beginning of the 21st century. It would accelerate a technical reformation for the applications in new energies, bioscience and biomedical engineering, artificial intelligence, electronic skin, wearable electronic clothing, Internet of things, and electrical insulation. This review summarises the recent development and achievements of nanodielectrics, including space charge suppression, high energy density storage, partial discharge resistance, non-linear field grading properties, high thermal conductivity, and future applications in biomedical area. Special attention is given to two representative interface models that are the Lewis's diffusion electrical double-layer model and Tanaka's multi-core model. At last, some issues related to the technology of nanodielectrics have also been discussed.

The ferroelectric (FE) to antiferroelectric (AFE) phase transition tuning the temperature range of electrocaloric (EC) effects was investigated using phenomenological Landau–Devonshire theory. Contrary to ferroelectric to paraelectric (PE) phase transitions for electrocaloric effects, the ferroelectric to antiferroelectric phase transition was adopted to obtain large entropy changes under an applied electric field in a Sm-doping BiFeO3 system. In addition, the doping composition and hydrostatic pressure was observed to tune the ferroelectricantiferroelectric–paraelectric phase transition temperatures and broaden the operating temperature range of electrocaloric effects. The optimal wide temperature range of ~78 K was observed at 3 GPa compressive hydrostatic pressures and 0.05 Sm-doping BiFeO3. The present study paves the way to designing high efficiency cooling devices with larger operating temperature spans.

The distortion and uneven distribution of electric field in high-voltage direct current (HVDC) terminal insulator is the key problem for stable running of the power transmission system. Semiconducting flexible materials filled polymer-matrix composites with non-linear conductivity have also been considered to modify the distribution of electric field in cable terminal. Several factors having influence on the non-linear conductivity will be analysed in this review.

Solid polymer electrolytes (SPEs) have great potential to address the safety issues of lithium (Li)-ion batteries when compared with conventional liquid electrolytes, which makes them a promising alternative for next-generation high-energy batteries. In this work, poly(ethylene oxide)-lithium perchlorate (PEO–LiClO(4)) polymer electrolytes for Li-ion batteries were prepared using electrospinning. The crystallinity, ionic conductivity as well as mechanical properties were investigated. Ionic conductivities and mechanical properties of PEO–LiClO(4) based SPE have been obviously increased by incorporating modified TiO(2) nanofibres (TNFs) than TiO(2) nanoparticles (TNPs), due to that both TNFs and TNPs can decrease the crystalline phase concentration of PEO and increase segmental flexibility of PEO. The SPE with 3 wt% TNFs exhibits the highest conductivity of 5.308 × 10^−5 S cm^−1 at 20°C and higher tensile strength of 13.8 MPa. These results highlight the potential of utilising the electrospinning method to improve the ionic conductivity of SPEs.

The equation εeff ∝ (ϕc - ϕ)-s which shows the relationship between effective dielectric constant (εeff) and the filler concentration (φ), is widely used to determine the percolation behavior and obtain parameters, such as percolation threshold φc and the power constant s in conductor–dielectric composites (CDCs). Six different systems of CDCs were used to check the expression by fitting experimental results. It is found that the equation can fit the experimental results at any frequency. However, it is found that the fitting constants do not reflect the real percolation behavior of the composites. It is found that the dielectric constant is strongly dependent on the frequency, which is mainly due to the fact that the frequency dependence of the dielectric constant for the composites close to φc is almost independent of the matrix.