Self-assembled wide bandgap nanocoatings enabled outstanding dielectric characteristics in the sandwich-like structure polymer composites

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.

Insight into charge-induced flashover at the gas–solid interface in DC gas-insulated systems

“…Wang et al, for instance, identified deep trap regulation by assessing surface charge dissipation at a 1 nm scale using KPFM [55]. Moreover, they utilized this method to evaluate the charge dissipation properties of various coatings [56,57]. Likewise, Zhang et al performed nanoscale surface charge mapping by KPFM to demonstrate Schottky barrier recovery with a nano-assembly coating [58].…”

Polymer Dielectrics with Outstanding Dielectric Characteristics via Passivation with Oxygen Atoms through C–F Vacancy Carbonylation

“…Due to their advantages of low cost, easy processing, light weight, high chemical stability, high reliability, and good insulation properties, polymer dielectrics play a very important role in many applications, such as electrical and electronic equipment and energy storage. − For example, polymer dielectrics are the material of choice for high-energy-density film capacitors − and are used as the core of insulating frames in advanced electronic devices, power systems, electrified transportation, and aerospace equipment. − However, with the development trends of equipment integration, miniaturization, and high power, the insufficient electric strength of polymer dielectrics has become a bottleneck problem restricting the development of electrical equipment operating under increasingly high electric field strengths. − In a high-field environment, polymer dielectrics may undergo flashover or breakdown, resulting in insulation failure and equipment damage. − At present, there are many solutions for improving the electrical strength of polymer dielectrics under a high field, such as coating, − doping modification, − multilayer composites, , and fluorination treatment. , Unfortunately, although these solutions can effectively improve the electrical strength of polymer dielectrics, they are still difficult to apply industrially on a large scale due to factors such as high cost, poor long-term stability, and unstable products and the fact that these methods significantly reduce other key properties of polymer dielectrics. The reason for this problem is that these methods enhance electric strength by greatly changing the original material system without directly mitigating the root cause of the reduced electric strength of polymer dielectrics, that is, deep traps.…”

“…The reason for this problem is that these methods enhance electric strength by greatly changing the original material system without directly mitigating the root cause of the reduced electric strength of polymer dielectrics, that is, deep traps. Deep traps in polymer dielectrics directly affect their electric strength. − As localized states of electrons deep in the bandgap, deep traps are the accumulation centers of electron and hole carriers, resulting in a large amount of charge accumulation. − This causes local electric field distortion and triggers flashover and breakdown. − ,− Therefore, it is of great significance to develop a low-cost method that allows the large-scale direct regulation of deep traps in polymer dielectrics that perform stably after treatment.…”

“…The highest charge density decreased from −92.86 to −42.3 pC/mm 2 . The reduction in accumulated charge demonstrated effective deep trap passivation and a reduced risk of insulation failure in the material. − ,− Then, we tested the change in the flashover voltage. As shown in Figure f, the flashover voltage of PTFE after passivation treatment increased from 31.1 to 46.7 kV, an increase of 50.1%.…”

“…As shown in Figure f, the flashover voltage of PTFE after passivation treatment increased from 31.1 to 46.7 kV, an increase of 50.1%. PTFE accumulates charge when applied in actual electrical equipment operating in an electric field environment. ,,,− To simulate the flashover of PTFE in its actual use, we performed a precharge experiment. After PTFE was preattached with opposite polarity charges, the flashover voltage reduced to 19.5 kV, while the flashover voltage of PTFE after deep trap passivation was 36.1 kV, which was much higher than that of the original PTFE.…”