High energy storage density and low energy loss achieved by inserting charge traps in all organic dielectric materials

Abstract

Polymer based dielectrics are widely used in metalized film capacitors because of their high breakdown strength, prominent machining performance and low cost. Current commercial polymer dielectrics suffer from either low discharging efficiency or low discharged energy density, thus impeding the development of highly packed electronic devices and high pulse electric systems. Herein, a family of all organic linear dielectric polymers containing varied contents of p–π conjugated N-vinyl carbazole (VK) units as charge traps are reported. The polymers are synthesized from the copolymerization of methyl methacrylate (MMA) and varied loading contents of VK, which offers homogeneously distributed trap sites to capture free charge carriers in the polymers. The fabricated polymers containing 3.6 mol% VK units show the maximum discharged energy density of 15.7 J cm⁻³ at 750 MV m⁻¹ along with an ultra-high discharging efficiency of 88%. Based on a combination of thermally stimulated depolarization currents (TSDCs), pulsed electro-acoustic (PEA) and density functional theory analysis (DFT), the high breakdown strength, large energy density and high discharging efficiency of the copolymers are ascribed to the excellent space charge trapping effect of VKs. This work offers a new strategy for the fabrication of all organic polymer dielectrics for realizing high discharged energy density and high discharging efficiency simultaneously.