Internal Biasing in Relaxor Ferroelectric Polymer to Enhance the Electrocaloric Effect

Abstract

The relaxor ferroelectric materials, because of their large and reversible electric fi eld induced polarization, have been demonstrated to possess giant electrocaloric effect (ECE) over a broad temperature range, which are attractive for refrigeration with high energy effi ciency and environmental friendliness. However, high electric fi elds are required to generate the giant ECE in these materials, posing challenge for these materials in practical cooling devices which also require high reliability and low cost. Here, a general approach is reported, for example, establishing an internal bias fi eld in these relaxor ferroelectric polymers, to signifi cantly improve ECE which can be induced at low electric fi elds. It is demonstrated that in a polymer blend (nanocomposite) with a properly controlled normal ferroelectric in nanophase dispersion in the relaxor polymer matrix, the charge neutrality in the blends can cause an internal biasing fi eld, leading to more than 45% enhancement in the ECE at low electric fi eld (≈50 MV m −1 ). This internal biasing approach provides a universal strategy to enhance other low fi eld responses such as the electromechanical response in relaxor ferroelectrics.

Interface‐Strengthened Polymer Nanocomposites with Reduced Dielectric Relaxation Exhibit High Energy Density at Elevated Temperatures Utilizing a Facile Dual Crosslinked Network

“…Dielectric capacitors, which store energy electrostatically in dielectric materials in the form of an electric field between two electrodes, have the highest power density (on the order of megawatts) and the fastest charge/discharge rate (on the order of microseconds) among the electrical energy storage devices, [ 1–3 ] providing parts for numerous electric circuits with a wide range of power rating, [ 4 ] for power plants that hold ultrahigh voltage to transport electricity, [ 5 ] and for new applications such as artificial muscles for soft robotics, [ 6 ] solid‐state refrigeration, [ 7,8 ] and micro‐electromechanical system (MEMS). [ 9 ]…”

Electrostatic Actuating Double‐Unit Electrocaloric Cooling Device with High Efficiency

“…Moreover, EC performance can also be enhanced by adjusting the component ratio of the mixture of P(VDF‐TrFE) and P(VDF‐TrFE‐CFE). [ 28,29 ] Nevertheless, the research on modification of P(VDF‐TrFE‐CFE), especially in the field of flexible refrigeration devices, is still insufficient. In addition, the optimization of the EC refrigeration‐device architecture is also necessary to further improve the cooling performance of the device.…”

Electron structure in modified BaTiO 3 /poly(vinylidene fluoride) nanocomposite with high dielectric property and energy density

“…Dielectric polymer film is especially suitable for the applications in energy storage and transformation because of its remarkable electrical and mechanical properties, and becomes the research focus in past 20 years [1][2][3][4][5]. The electrostatic storage capability of insulated film is determined by the dielectric constant and the electric breakdown, which indicates that next generation of dielectric films not only exhibit high permittivity, also retain high dielectric strength with low energy dissipation [2,4].…”