Low Remanent Polarization for High Energy Density by Poly(vinylidene fluoride-co-chlorotrifluoroethylene)/Silicon Dioxide Nanocomposites

Nowadays, dielectric materials with high energy storage density play a vital role in the energy storage capacitors. To increase the storage density, 0–3 composite films based on poly(vinylidene fluoride-co-chlorotrifluoroethylene) [P(VDF-CTFE)] and silicon dioxide (SiO2) nanoparticles were prepared by a solution casting method. The composite with 10% SiO2 has a discharged energy density of 2.73 J/cm3 at 200 MV/m. Furthermore, the local electric field distribution in the P(VDF-CTFE)/SiO2 nanocomposites was analyzed by experiments combined with model simulation. And the relationship of displacement (D) and remanent polarization (Pr) with the current at the applied electric field was investigated. It indicates that during the charging phase, a large positive (+) current value is conducive to obtaining high electrical displacement while in the discharge phase, a small negative current value will be beneficial to achieve a smaller remanent polarization value. Therefore, the addition of low dielectric permittivity fillers (SiO2) contributes to the displacement of the composite at higher electric fields and maintains the Pr in a small range, thus achieving a higher discharged energy density.