High-Temperature Flexible Nanocomposites with Ultra-High Energy Storage Density by Nanostructured MgO Fillers

摘要

High-temperature performance is critical to the dielectric polymer capacitorsused in environment electronic and high-power applications. Here, the authorsreport a composite comprising polyimide (PI) dielectric polymers blendedwith high-insulation magnesium oxide (MgO) nano-filler that exhibits highbreakdown strength, wide temperature range, and low dielectric loss. However,most dielectric polymers possess excellent energy storage properties atroom temperature and cannot be used at high temperatures above 100 ℃.Polyimide dielectric nanocomposites prepared by in situ polymerization, whichare composed of easily prepared MgO fillers, have different morphologies,such as nanoparticles (0D), nanowires (1D), and nanoplates (2D). The experimentalresults show that the insulation behavior and breakdown strength ofpolymer composites are closely related to the morphology of MgO fillers, andthe rationality of this conclusion is further proved by finite-element simulationresults. The polymer composites containing ultra-low content (0.5 vol%)MgO nanosheets produce an ultra-high capacitance performance, that is, thedischarge energy density is 4.78 J cm~(?3) at 150 ℃, which is significantly betterthan the most reported dielectric polymers and nanocomposites.