Achieving Higher Dielectric and Energy Storage Performances of Methyl Methacrylate-co-glycidyl Methacrylate Films through the Nanocomposite Strategy

Polymer-based nanocomposite dielectric films with excellent breakdown strength and high discharged energy density are desired for advanced dielectric film capacitors. Herein, a series of methyl methacrylate (MMA) and glycidyl methacrylate (GMA) copolymer (MG) nanocomposite films with organic montmorillonite (OMMT) as a modifier were prepared by a solution-processed method. Density functional theory proved that the introduction of GMA groups in the MG copolymer effectively formed deep energy traps, which were beneficial to free carrier capture, weak leakage current density, and high breakdown strength. The introduction of the 2D OMMT nanosheets further improved the dielectric constant of the MG copolymer through interfacial polarization. In addition, the formation of nano interfaces between MG and OMMT also provided deep traps, which limited charge injection and migration, resulting in lower dielectric/conductive losses and higher breakdown strength. Meanwhile, the addition of OMMT hindered further extension of electrical trees in the nanocomposite films due to the 2D structure according to finite element simulation. The energy storage results indicated that the MG/OMMT nanocomposite film with 1 wt % OMMT concentration achieved a 780 MV/m breakdown strength, 10.95 J/cm 3 discharged energy density, and 85% energy efficiency. Therefore, this research provides a simple and feasible strategy for the manufacture of thin-film capacitors.