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 (P_r) 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 P_r in a small range, thus achieving a higher discharged energy density.