Dielectric energy storage by prepolarized, polymer embedded ferroelectric particles

In order to maximize the dielectric energy density, the knee of the polarization curve P(E) should coincide with the dielectric strength E_s of the material. On the other hand, the efficiency of an energy storage device is also an important parameter. Therefore, hysteresis losses should be small. Two successful possibilities for material optimization have been investigated: embedding the ferroelectric powder in polymers allows one to adjust the permittivity ε_τ and the polarization curve by modifying the powder/polymer-concentration. The polarization curve is modified and the coercivity E_C is minimized by prepolarizing the sample in a bias field E_Bias, which is acting parallel to the sample plane during the solidification process. The aligned dipoles are then rotated (against the crystal energy) in the direction of the applied field E, which is acting perpendicular to the dielectric plate. In this way the energy density can be increased up to W=10⁶-10⁷ J/m³ to make capacitors replace electro-chemical batteries for ultra quick charging/discharging applications