Super Electrical Insulating Materials Based on Honeycomb-Inspired Nanostructure: High Electrical Strength and Low Permittivity and Dielectric Loss

The high breakdown field strength is the most important index to evaluate the performance of insulating materials. It is theoretically found that the breakdown field strength of dielectric samples can be significantly improved by up to 1-2 orders of magnitude by constructing nanopore structures. Thus, bridged silsesquioxane super electrical insulating materials (BSSEIM) are developed with nanosized pore structures and their extremely high electrical insulation performance is realized. The results indicate that the breakdown field strength of the BSSEIM is dramatically higher than aluminosilicate fiber insulating materials (ASFIM) by 570.5% for dry samples and 118.1% for oil-impregnated samples. Specifically, the prepared BSSEIM samples have excellent dielectric performances with permittivity and dielectric losses that are only 51.3% and 1.1% of ASFIM, which are significantly lower than most existing insulating materials. Finally, the theoretical analysis indicates that the nanopore structures can effectively limit the scale of the head size for an electron avalanche and significantly reduce the number of effective gas molecules by dividing the gas into nanounits. This significantly inhibits the ionization of gas molecules and improves the breakdown field strength of samples. This discovery overturns previous understandings of traditional insulating materials and opens an avenue toward super electrical insulating materials.