Breakdown Strength Characteristics Research Articles

Advancements and challenges in BaTiO3-Based materials for enhanced energy storage

Numerous researchers worldwide have been motivated to develop highly effective, environmentally acceptable green energy sources as a result of the recent sharp increase in energy use and the need for low emission levels. The energy generated from various renewable sources can be stored efficiently with a system that has a high energy density and high energy efficiency. Due to their enhanced dielectric, ferroelectric, and breakdown strength characteristics, BaTiO3 based dielectric/ferroelectric ceramic materials have received a lot of interest for energy storage applications in the past tw decades. In the present work, a thorough analysis of recent advancements in composites and single-phase BaTiO3 materials with enhanced energy storage performance. This review's main focus is on the crucial tactics and theoretical frameworks for improving the energy efficiency and recovered energy storage density of various BaTiO3-based materials. A thorough summary has been provided with the most recent developments in BaTiO3 based materials for multi-layered ceramic capacitors (MLCCs), pulse power capacitors, piezoelectric transducers, energy harvesting, electric vehicle batteries, and high-power electronic devices in order to confirm the commercial applications of BaTiO3 based single phase as well as multi-phase layered structures and composites.

Prospects for the Development of High Energy Density Dielectric Capacitors

In this paper, the design of high energy density dielectric capacitors for energy storage in vehicle, industrial, and electric utility applications have been considered in detail. The performance of these devices depends primarily on the dielectric constant and breakdown strength characteristics of the dielectric material used. A review of the literature on composite polymer materials to assess their present dielectric constants and the various approaches being pursued to increase energy density found that there are many papers in which materials having dielectric constants of 20–50 were reported, but only a few showing materials with very high dielectric constants of 500 and greater. The very high dielectric constants were usually achieved with nanoscale metallic or carbon particles embedded in a host polymer and the maximum dielectric constant occurred near the percolation threshold particle loading. In this study, an analytical method to calculate the dielectric constant of composite dielectric polymers with various types of nanoparticles embedded is presented. The method was applied using an Excel spreadsheet to calculate the characteristics of spiral wound battery cells using various composite polymers with embedded particles. The calculated energy densities were strong functions of the size of the particles and thickness of the dielectric layer in the cell. For a 1000 V cell, an energy density of 100–200 Wh/kg was calculated for 3–5 nm particles and 3–5 µ thick dielectric layers. The results of this study indicate that dielectric materials with an effective dielectric constant of 500–1000 are needed to develop dielectric capacitor cells with battery-like energy density. The breakdown strength would be 300–400 V/µ in a reverse sandwich multilayer dielectric arrangement. The leakage current of the cell would be determined from appropriate DC testing. These high energy density dielectric capacitors are very different from electrochemical capacitors that utilize conducting polymers and liquid electrolytes and are constructed much like batteries. The dielectric capacitors have a very high cell voltage and are constructed like conventional ceramic capacitors.

Nonlinear conductivity and breakdown strength characteristics of silicon carbide and hexagonal boron nitride co-doped epoxy resin composites

In this study, the method of co-doping semi-conductor silicon carbide (SiC) and insulating inorganic phase hexagonal boron nitride (h-BN) in epoxy resin (EP) composites has been proposed for considering both the nonlinear conductivity and the breakdown strength. First, the epoxy-based composites were fabricated and prepared by hot press vulcanization. Then, the phase structure and the microstructure of the composites were characterized by XRD and SEM. Finally, the nonlinear conductivity and the breakdown strength of the composites were tested. The results indicate that the breakdown strength of the 1 wt. % h-BN/3 wt. % SiC/EP composite reaches 115.6 kV/mm, which is 4 times higher than that of the single-doped 3 wt. % SiC/EP composite. More importantly, the appropriate h-BN and SiC contents of the co-doped EP composites still exhibit excellent nonlinear electrical conductive properties. The results indicate that both the nonlinear conductivity and the breakdown strength have been obtained by the semi-conductor and insulator co-doping strategy.

Breakdown characteristics of carbon dioxide–ethane azeotropic mixtures near the critical point

The properties of traditional dielectric media have been a major limiting factor impacting the design and operation of many applications spanning from particle accelerators over x-ray radiography and radiotherapy to electrical power systems. Supercritical fluids (SCFs) combine the properties of high dielectric strength, low viscosity, and excellent heat transfer capability. Here, we show, for the first time, the anomalous breakdown strength characteristics of SCF mixtures, such as carbon dioxide (CO2) and ethane (C2H6) mixtures and their azeotropic mixture under supercritical conditions. Our experiments suggest that the dielectric behavior deviates significantly from the established theory of gas discharge known by the work of Townsend and Paschen. Our results reveal that not only pure substances such as CO2 exhibit a discontinuity of the dielectric strength near the critical point, but the supercritical mixture also manifests a discontinuity. The effect of random particle clustering in the pure substance and the mixture is observed, which impacts the mean free path of electrons. We present the measured breakdown voltage in a 0.1 mm gap with a uniform electric field over a wide range of mixture ratios and fluid densities and use a mathematical model by Stanley to show the density fluctuations that peak at around the critical point. By adjusting the mixing ratio, we prove that the mixture forms a useful combination of dielectric strengths and critical points and broadens the applicability of SC mixtures for a variety of purposes.

THE INFLUENCE OF POLYPROPYLENE LAMINATED PAPER ON THE BREAKDOWN STRENGTH OF INSULATION FOR HIGH TEMPERATURE SUPERCONDUCTING CABLE

Polypropylene Laminated Paper (PPLP) and Kraft paper has been used as ac power insulation for conventional cable as well as high temperature superconducting (HTS) cable because of its prominent insulating characteristics. However, research on the use of PPLP/Kraft insulation for HTS cables are thinly scattered. In this paper, the effect of PPLP on the breakdown strength of PPLP/Kraft multi-layer sample impregnated with liquid nitrogen (LN2) under ac and impulse applied voltage was studied. In addition, the breakdown strength characteristics of PPLP and Kraft samples were also investigated in order to determine breakdown strength characteristics of PPLP/Kraft insulation directly. It was found from the experimental data that the breakdown strength increases as the component ratio of PPLP in the PPLP/Kraft sample increases and is slightly affected by the inserting position of PPLP but in impulse case, the breakdown strength strongly depends on the number of PPLP and the relative position of PPLP.

Increase in Breakdown Strength of PB Film by Addition of Polycyclic Compound

The An increase in dc breakdown strength (BDS) for LDPE film was found using the additives of polycyclic compounds: anthracene(An), perylene(Pr), 9, 10 bromo-anthracene(Br_An), 1, 7 bromo-perylene(Br_Pr). We also used an additive of p-nitorobenzene-azoresorcinol(Az_hn). The experimental results indicate that all the additives used are effective in increasing BDS. The most effective additive is Br_An. BDS for the film with this additive is about 1.6 times higher than that for the film without additive. These results are observed in the temperature range between -20°C and 20°C. The BDS characteristics indicate that the breakdown of film may be due to an electron avalanche from the cathode. The reason for the increase in BDS is studied by comparing the experimental results for the five additives. UV absorption spectra for the films with additive suggest that the increase in BDS may not result mainly from the kinetic energy absorption due to the excitement of the additive at the collision between additive and electron carrier. TSC curves indicate that the quantity of negative charge trapped in the film is increased by the existence of the additive, which may locate at the boundary between the crystalline and amorphous regions in the film. It is considered that the increase in BDS may be achieved by a trapping of the electron carrier by the additive. The electron carrier scattering due to the dipole moment of the additive is no effective factor for the increase of BDS in this study because the polycyclic compounds used have no dipole.

Over recovery in low pressure spark gaps-confirmation of pressure reduction in over recovery

The over recovery in sparkgaps (Nagesh, 1997, Nagesh et al., 1999) operating along the left-hand side of Paschens' characteristics is due to pressure reduction in the gap after the first pulse discharge. This pressure reduction leading to over recovery in low pressure spark gaps has been verified using a low pressure spark gap with two spark gaps placed one above the other in the same chamber. The breakdown voltage strength characteristics of the second gap has been determined for gap spacings of 3.5 mm to 10 mm, diffusion of plasma in the direction of vacuum pumping and opposite, at a pressure of 2.1 Pa for hydrogen gas. The vacuum pumping direction has a great influence on the breakdown strength characteristics of second gap after the first gap discharge. The breakdown voltage of the second gap can exceed its self breakdown voltage only 1) when the diffusion of plasma and vacuum pumping direction are same and 2) when the second gap spacing is greater than or equal to first gap spacing. Shorter gaps can always have breakdown voltage lower than or equal to their self breakdown voltage. The experimental setups, behavior of self breakdown voltages of second gap due to breakdown in the first gap, over recovery characteristics of spark gaps, the results, and discussions are presented here.