Ultrahigh Energy Density in Continuously Gradient‐Structured All‐Organic Dielectric Polymer Films

Abstract

High‐performance dielectric capacitors are critical for advanced electronics and electrical power systems. Polymeric dielectrics have been widely investigated for using in dielectric capacitors because of their high dielectric constants, flexibility, low density, and easy processability. However, it is still challenging to achieve simultaneous improvements in both energy density and efficiency in these dielectric polymers. Here, we report ferroelectric polyvinylidene‐fluoride‐based all‐organic dielectric polymer films with continuous compositional gradient structure are reported by modulating the spatial distribution of polymethyl‐methacrylate components, prepared via a facile and scalable additive manufacturing method. The continuous out‐of‐plane composition gradient in the all‐organic dielectric polymer films allows to tune electrical and mechanical behaviors, and thus induces a notably enhanced breakdown strength by modulating the electromechanical breakdown process related to the coupling of local electric field and stress. An ultrahigh discharge energy density of 38.8 J cm−3 along with a high discharge efficiency of >80% is achieved at the electric field of 800 kV mm−1 in the gradient polymer films, which is the highest energy density reported thus far in polymer‐based dielectrics including their nanocomposites and the highest energy efficiency achieved along with an energy density of >30 J cm−3.

Perspective on interface engineering for capacitive energy storage polymer nanodielectrics

“…At the same time, due to the simultaneous increase of ε r and E b , enhanced U e was obtained for these composite dielectrics with low content and wide bandgap nanoparticles. 91–97 This may be caused by the significantly enhanced dipole polarization of the matrix and large interface content accompanying the nano-sized particles. However, at present, the research on this type of composite is neither comprehensive nor in-depth, and a reasonable and perfect dielectric theory and model are to be urgently established.…”

High Conduction Band Inorganic Layers for Distinct Enhancement of Electrical Energy Storage in Polymer Nanocomposites

“…To date, two strategies seem to be effective in enhancing the U e of polymer composites. One is utilizing high-k nanofiller to realize a concurrent increase of ε r and E b , which can be divided into two aspects, synthesizing hybrid high-k nanofiller and designing the hierarchical structure of dielectric films [ 14 – 16 ]. However, these two approaches both are tanglesome (either in nanofiller synthesis or film fabricating process).…”

Double gradient composite dielectric with high energy density and efficiency

“…In addition, in gradient structure composites, the dielectric mismatch of the macro interface between the adjacent layers leads to charge transfer in the composite film form energy barrier; thus, the insulation and polarization characteristics are improved. 47 It is also confirmed that the dielectric/electrode interface plays a more critical role than the dielectric in restraining the leakage current. 48 For BNNS inverse concentration gradient distribution, a smaller leakage current density is obtained for the component with the smallest TiO 2 gradient span, and the variation of the BNNS gradient span has little effect on the leakage current (Fig.…”