Achieving high breakdown strength and energy density in all-organic sandwich-structured dielectrics by introducing polyacrylate elastomers

Abstract

Improving the discharge energy density (U_d) of dielectric polymer film capacitors is of great significance in modern electric power systems because it is conducive to the miniaturization, lightweight feature and integration of electronic devices. Herein, by selecting ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (PVTC) as the polymer matrix and polyacrylate elastomer (DE) and poly(methyl methacrylate) (PMMA) as organic fillers, a series of all-organic sandwich-structured polymer films was prepared via simple layer-by-layer solution casting to obtain an ultrahigh U_d. In order to resist charge injection from the electrodes and enhance the breakdown strength, 20 wt% PMMA/PVTC blended layers were chosen as the two outer insulating layers. The DE/PVTC blended layer with different DE contents was employed as the central polarization layer for enhancing the dielectric displacement. The effect of DE content and film structure on the energy storage property of the sandwich-structured polymer films was thoroughly studied. The results indicated that the highest U_d of 20.1 J cm⁻³ at 790 kV mm⁻¹ was achieved when the loading of DE reached 15 wt% in the DE/PVTC central layer, which was much higher than that of the pure PVTC film, PMMA/PVTC blended films and DE/PVTC blended films. Moreover, the sandwich-structured polymer films presented excellent mechanical properties, power density and cycling stability. This work provides a new approach for fabricating industrially viable ferroelectric polymer flexible dielectrics with a layered architecture and organic elastomer fillers.