Polymer dielectrics with high energy density and low dielectric loss are highly desired due to the rapid development of electric devices. Among known polymers, poly(vinylidene fluoride-ter-trifluoroethylene-ter-chlorofluoroethylene) P(VDF-TrFE-CFE) is one of the promising materials for energy storage capacitor applications because of its high dielectric constant. Nevertheless, it suffers from high dielectric loss especially at the high electric field, which suppresses its breakdown strength and energy storage density. Herein, sandwiched structure dielectric films were fabricated by employing polymethyl methacrylate (PMMA) as the outer layer and P(VDF-TrFE-CFE) as the central layer. By modulating the thickness of the central layer, an enhanced discharged energy density of 7.03 J/cm³ is achieved at a high electric field of 480 MV/m, which is 132% more than that of P(VDF-TrFE-CFE) at its maximum electric field 300 MV/m. Meanwhile, this sandwiched structure film also retains a high discharge efficiency of 78% at 480 MV/m, which is never been seen in polyvinylidene fluoride-based polymers. Results show that PMMA acts as charge barrier and simultaneously enhance the breakdown strength and suppress the dielectric loss of P(VDF-TrFE-CFE).

The insulation as the root source of failure and ageing assessor makes it a crucial point for any power equipment design. The transformer's insulation requires an efficient dielectric fluid that acts as an ideal electrical insulant and better thermal transporter. The objective of attaining that idealism in dielectric medium leads to the addition of solvents (i.e. additive and other fluids) in the conventional medium as one of its approach. This study presents addition of new magnetic nanoparticle iron phosphide (Fe₃P) in insulating oil to achieve improved dielectric strength and withstand capability of the same conventional oil. A comparative study of nanofluids with different concentrations of nanofluids based on different insulating medium (i.e. synthetic ester and natural ester) has been performed. The concentration of additives and role of surfactant positively influences the dielectric characteristics of the base oil. The increase in breakdown strength is observed with a slight concentration of Fe₃P nanoparticles added in the insulating medium.

Dielectric nanocomposites with an enhanced energy density are highly desired in modern electronic and electrical power systems. In this study, the authors developed a new flexible dielectric nanocomposite thin film using Y-doped barium strontium titanate (Y:BST) nanoparticles as fillers and polyvinylidene fluoride as a polymer matrix. The nanocomposites exhibited a high energy density of 11.07 J/cm³ at 4300 kV/cm with a low filler content. Through the analysis of defect chemistry with X-ray photoelectron spectroscopy, the dopant Y³⁺ occupies A-site of the perovskite structure, which is associated with the generation of Ba&Sr vacancies and oxygen vacancies for charge compensation. As a result, TiO₆ ^2– octahedron distortion occurs, which is responsible for the enhanced dielectric permittivity. Meanwhile, the dielectric loss maintains a low level and the breakdown strength increases at a low filler loading, resulting in improved energy density.

Lead-free (1–x)(0.4BiScO₃–0.6BaTiO₃)-x(Bi_0.5Na_0.5)TiO₃ (BSBT–xBNT) ceramics were prepared by traditional ceramics preparation method. The energy storage characteristics, as well as dielectric spectrum curves of BSBT–xBNT ceramics, were systematically used in research. The ternary system formed perovskite solid solution with dense and homogenous microstructure. BSBT–xBNT ceramics exhibited slimmer and slanted hysteresis loops followed by higher saturation polarisation (P _max) and lower remnant polarisation (P _r), which induced high-energy storage density of 1.39 J/cm³ (E = 180 kV/cm). Ranging from 200 to 400°C, BSBT–xBNT ceramics had high permittivities, and a matching dielectric loss, which exhibited flat temperature coefficients of permittivity (TCɛ). The impedance spectroscopy analysis indicated that the non-Debye relaxation mechanism existed in BSBT–xBNT ceramics. BSBT–xBNT ceramics may have potential application value for the high-temperature capacitor.