Study of flexible nanodielectric materials (FNDMs) with high permittivity is one of the most active academic research areas in advanced functional materials. FNDMs with excellent dielectric properties are demonstrated to show great promise as energy-storage dielectric layers in high-performance capacitors. These materials, in common, consist of nanoscale particles dispersed into a flexible polymer matrix so that both the physical/chemical characteristics of the nanoparticles and the interaction between the nanoparticles and the polymers have crucial effects on the microstructures and final properties. This review first outlines the crucial issues in the nanodielectric field and then focuses on recent remarkable research developments in the fabrication of FNDMs with special constitutents, molecular structures, and microstructures. Possible reasons for several persistent issues are analyzed and the general strategies to realize FNDMs with excellent integral properties are summarized. The review further highlights some exciting examples of these FNDMs for power-energy-storage applications.

Flexible Nanodielectric Materials with High Permittivity for Power Energy Storage

A multi-core model, i.e. a simplified term of a multi-layered core model, is proposed as a working hypothesis to understand various properties and phenomena that polymer nanocomposites exhibit as dielectrics and electrical insulation. It gives fine structures to what are called "interaction zones". An interfacial layer of several tens nm is multi-layered, which consists of a bonded layer, a bound layer, and a loose layer. In addition, the Gouy-Chapman diffuse layer with the Debye shielding length of several tens to 100 nm is superimposed in the interfacial layer to cause a far-field effect. Nano-particles may interact electrically with the nearest neighbors each other due to this effect, resulting in possible collaborative effect. Such a multi-core model with the far-field effect is discussed, for example, to explain partial discharge (PD) resistance of polyamide layered silicate nanocomposites, and is verified to demonstrate its effectiveness.

Proposal of a multi-core model for polymer nanocomposite dielectrics

Perovskite lead-free dielectrics for energy storage applications

Polymer nanocomposites possess promising high performances as engineering materials, if they are prepared and fabricated properly. Some work has been recently done on such polymer nanocomposites as dielectrics and electrical insulation. This was reviewed in 2004 based on the literatures published up to 2003. New significant findings have been added since then. Furthermore, a multi-core model with the far-distance effect, which is closely related to an "interaction zones", has been proposed from consideration of mesoscopic analysis of electrical and chemical structures of an existing interface with finite thickness. It is speculatively examined in the paper how the model works for various properties and phenomena already found in nanocomposites as dielectrics focusing on electrical characteristics, resistance to high voltage environment, and thermal properties.

Dielectric nanocomposites with insulating properties

Polymer nanocomposites are defined as polymers in which small amounts of nanometer size fillers are homogeneously dispersed by only several weight percentages. Addition of just a few weight percent of the nanofillers has profound impact on the physical, chemical, mechanical and electrical properties of polymers. Such change is often favorable for engineering purpose. This nanocomposite technology has emerged from the field of engineering plastics, and potentially expanded its application to structural materials, coatings, and packaging to medical/biomedical products, and electronic and photonic devices. Recently these 'hi-tech' materials with excellent properties have begun to attract research people in the field of dielectrics and electrical insulation. Since new properties are brought about from the interactions of nanofillers with polymer matrices, mesoscopic properties are expected to come out, which would be interesting to both scientists and engineers. Improved characteristics are. expected as dielectrics and electrical insulation. Several interesting results to indicate the foreseeable future have been revealed, some of which are described on materials and processing in the paper together with basic concepts and future direction.

Polymer nanocomposites as dielectrics and electrical insulation-perspectives for processing technologies, material characterization and future applications

A new high-voltage, high-speed pulsed electro-acoustic (PEA) apparatus for real-time measurements of space-charge distribution in solid insulators subjected to rapidly varying voltages is described. Very high-rate PEA measurement is accomplished with the use of a high-speed real-time data acquisition module known as the `Eclipse' unit and a purpose-built high-voltage FET switch pulse generator. Real-time space-charge measurements with good phase resolving capability can be made under time varying applied stresses, e.g. voltage transients or ac conditions. The high-field PEA system has been used to investigate the space-charge dynamics in polyethylene samples stressed by 0.2 and 50 Hz sinusoidal ac voltages.

https://iopscience.iop.org/article/10.1088/0957-0233/12/8/333/pdf

Measurement of space-charge distributions in solid insulators under rapidly varying voltage using the high-voltage, high-speed pulsed electro-acoustic (PEA) apparatus

In surface plasmon resonance (SPR) fibre-optic sensors, the optical power transmittance is important in determining behaviour. In this paper numerical calculations are used to estimate the optical power transmittance of SPR fibre-optic sensors. These analytical estimations can be applied in SPR fibre-optic sensors both with a transducing layer and without a transducing layer. The results of these numerical calculations agree well with previously published experimental results. This work will aid in the design of SPR fibre-optic sensors in terms of geometrical structure, materials and dynamic range as well as allowing the prediction of performance and of limitations of the design.

Analytical estimates of the characteristics of surface plasmon resonance fibre-optic sensors

Alkyl ester derivatives were synthesized from laboratory purified palm kernel oil. The steps in the synthesis involved transesterification of palm kernel oil to produce a methyl ester, followed by epoxidation and then the grafting of side chains by esterification with propionic and butyric anhydride. The dielectric and thermal properties of the ester derivatives were analyzed and compared with the methyl ester. The melting point of the ester derivatives were found to reduce with side chain attachment and antioxidant improved its thermal stability. The dielectric loss was dominated by mobile charged particles and the chemical modification appeared to increase the rate at which electric double layer was formed at the electrode-liquid interface. The esters possessed excellent breakdown strengths suggesting that the processing to optimize their physical properties did not have a negative influence on their electrical breakdown strength. This product may prove useful as an insulation fluid in Electrical Power Transformers.

/pdf/effect-of-side-chains-on-the-dielectric-properties-of-alkyl-4hcwq55f97.pdf

John C. Fothergill

Papers

Measurement of space-charge distributions in solid insulators under rapidly varying voltage using the high-voltage, high-speed pulsed electro-acoustic (PEA) apparatus

Analytical estimates of the characteristics of surface plasmon resonance fibre-optic sensors

Effect of side chains on the dielectric properties of alkyl esters derived from palm kernel oil

Electrochemical lesions in the rat liver support its potential for treatment of liver tumors.

Analytical estimates of the characteristics of surface plasmon resonance fibre-optic sensors