Dielectric capacitors are the key components in advanced electronics and electrical systems owing to their highest power density among the electrical energy devices. [1][2][3][4][5][6][7] While ceramic dielectrics are of large dielectric constants and high thermal stability, [8][9][10][11][12] polymer dielectrics possess high tolerance to voltage, great reliability, scalability, and light weight, and therefore are preferred for high-energy-density high-power film capacitors. [13][14][15][16][17] However, the current polymer dielectrics are unable to match the temperature requirements of the emerging applications of electrical energy storage and conversion in harsh environments [18][19][20][21][22] because of their inherently poor thermal stability. For example, while the near-engine-temperature in electric vehicles can reach to above 120 °C, [23] the operating temperature of biaxially oriented polypropylene (BOPP), which is the best commercially available polymer dielectric and currently used in power inverters of electric vehicles, is below 105 °C. [24] The wide bandgap semiconductors like silicon carbide (SiC) and gallium nitride that are well positioned to replace traditional silicon power devices boost the operating temperatures of next-generation capacitors beyond 150 °C. [19] To address these urging needs, a variety of engineering polymers with high thermal stability, such as polyimides (PIs) and fluorene polyesters (FPEs), have been exploited as high-temperature dielectric materials. [20,25] Unfortunately, all the polymers show poor charge-discharge efficiencies under elevated temperatures and high applied fields, [26] which is due to sharply increased electrical conduction attributable to various temperature-and field-dependent conduction mechanisms, e.g., charge injection at the electrode/dielectric interface. [27,28] Ceramic dielectrics are relatively insensitive to temperature and able to maintain the energy-storage performance throughout a broad temperature range, [8][9][10][11][12] but they still suffer from considerable energy loss under high electric fields and elevated temperatures. [29] More recently, the addition of 2D wide bandgap nanostructures such as boron nitride nanosheets (BNNSs) into the polymer has been demonstrated to effectively reduce the conduction loss and largely improve the charge-discharge High-temperature capability is critical for polymer dielectrics in the nextgeneration capacitors demanded in harsh-environment electronics and electrical-power applications. It is well recognized that the energy-storage capabilities of dielectrics are degraded drastically with increasing temperature due to the exponential increase of conduction loss. Here, a general and scalable method to enable significant improvement of the high-temperature capacitive performance of the current polymer dielectrics is reported. The high-temperature capacitive properties in terms of discharged energy density and the charge-discharge efficiency of the polymer films coated with SiO 2 via plasma-enhanced chemical...

Dielectric polymers for electrostatic energy storage suffer from low energy density and poor efficiency at elevated temperatures, which constrains their use in the harsh-environment electronic devices, circuits, and systems. Although incorporating insulating, inorganic nanostructures into dielectric polymers promotes the temperature capability, scalable fabrication of high-quality nanocomposite films remains a formidable challenge. Here, we report an all-organic composite comprising dielectric polymers blended with high-electron-affinity molecular semiconductors that exhibits concurrent high energy density (3.0 J cm −3) and high discharge efficiency (90%) up to 200°C, far outperforming the existing dielectric polymers and polymer nanocomposites. We demonstrate that molecular semiconductors immobilize free electrons via strong electrostatic attraction and impede electric charge injection and transport in dielectric polymers, which leads to the substantial performance improvements. The all-organic composites can be fabricated into large-area and high-quality films with uniform dielectric and capacitive performance, which is crucially important for their successful commercialization and practical application in high-temperature electronics and energy storage devices.

We present in this paper a model for forecasting short-term electric load based on deep residual networks. The proposed model is able to integrate domain knowledge and researchers' understanding of the task by virtue of different neural network building blocks. Specifically, a modified deep residual network is formulated to improve the forecast results. Further, a two-stage ensemble strategy is used to enhance the generalization capability of the proposed model. We also apply the proposed model to probabilistic load forecasting using Monte Carlo dropout. Three public datasets are used to prove the effectiveness of the proposed model. Multiple test cases and comparison with existing models show that the proposed model is able to provide accurate load forecasting results and has high generalization capability.Index Terms-Short-term load forecasting, deep learning, deep residual network, probabilistic load forecasting.

Epoxy-based model insulators were manufactured and fluorinated under a F2/N2 mixture (12.5% F2) at 50 °C and 0.1 MPa for 15 min and 60 min. Surface charge accumulation and decay behavior were studied with and without dc voltage application. The effect of direct fluorination on surface charge migration as well as on flashover voltage was verified. The obtained results show that the charge decay of epoxy-based insulators is a slow process, but the decay rate increases when an outer dc electric field is applied. The surface charge distribution is changed when a streamer is triggered on the insulator surface. The existence of heteropolarity surface charges can decrease the dc surface flashover voltage to some extent, while the surface flashover voltage is almost unchanged when charges of the same polarity accumulate on the insulator surface. The short time fluorinated insulator can modify the surface resistivity, and the rate of surface charge dissipation is greatly increased under a dc electric field.

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Ferroelectric polymer nanocomposites are widely used in capacitive energy storage, electrocaloric refrigeration, and mechanical energy harvesting due to their exceptional electric polarization property and ease of fabrication. It is generally considered that the abnormal performance of ferroelectric nanocomposites stems from the interfacial region between the polymer matrix and embedded nanoparticles. However, direct evidence of the distinct local electric polarization property at the interfacial region is not yet accessible. Herein, a modified Kelvin probe force microscopy (KPFM) method with nanoscale spatial resolution is reported for direct detection of local polarization property at the matrix/particle interface in ferroelectric nanocomposites. Typical ferroelectric nanocomposites are studied using the present method. It is quantitatively probed that the electric polarization at matrix/particle interfacial region is higher than the polymer matrix under applied electric fields. Taking into account the enhanced local electric polarization gauged by the modified KPFM, the dielectric property of ferroelectric polymer nanocomposites matches with bulk experimental characterizations, indicating that the established method is reliable. It is anticipated that the present method, opening up new possibilities in understanding the matrix/particle interfacial region, may help with judicious design and engineering of high‐performance ferroelectric polymer nanocomposites.