Significantly enhanced breakdown strength and energy density performances of methyl methacrylate-co-glycidyl methacrylate nanocomposites filled with BNNs@PDA-Ag hybrid structures

Abstract

Electronic capacitor films based on polymer matrices and inorganic nanofillers capable of storing more energy play a crucial role in advanced modern electrical industries and devices. Herein, a series of nanocomposite films composed of “core–shell–dot” BNNs-PDA@Ag hybrid structures with multiple breakdown strength enhancement mechanisms as fillers and methyl methacrylate-co-glycidyl methacrylate (MG) copolymers as matrices were successfully synthesized. The introduced 2D and wide-bandgap BNNs not only enhanced the breakdown strength by taking advantage of their excellent physical properties, but also further improved their energy storage properties both at ambient and elevated temperatures through the formation of deeper traps at the organic–inorganic interface. In addition, especially under a strong electric field, the Coulomb-blockade effects of Ag nanoparticles immobilized by a PDA shell layer in the heterostructure of BN nanosheets avoided the breakdown. Ultimately, the energy density of 2.0 BNNs@PDA-Ag nanocomposite films was 9.35 J cm⁻³ at 640 MV m⁻¹ and room temperature with considerable efficiency (86%) under multiple breakdown strength enhancement mechanisms. Even at 90 °C and 120 °C, it still maintained energy densities of 5.46 J cm⁻³ and 4.32 J cm⁻³ with efficiencies of 84.79% and 76.81% under 460 MV m⁻¹ and 380 MV m⁻¹, respectively.