Remarkably enhanced polarisability and breakdown strength in PVDF-based interactive polymer blends for advanced energy storage applications

Flexible polymer-based dielectric capacitors with superior power density and stability are irreplaceable components in modern electrical devices. Among all dielectrics, ferroelectric relaxor materials are the most competitive candidates due to their high discharged energy density U_e and efficiency arising from their reversible polar nanodomains at high electric field. Poly(vinylidenedifluoride – trifluoroethylene - chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)), one of the most well-known ferroelectric relaxor polymers, suffers from some limitations, including, poor processability, relatively low breakdown strength and high cost, which inhibit its potential commercial use. In this work, these restrictions have been effectively addressed via a low-cost binary polymer blending route. Owing to the high compatibility and strong interactions between P(VDF-TrFE-CTFE) and Poly(vinylidene difluoride-hexafluoropropylene) (P(VDF-HFP)), the nanostructure of blends can be modulated, which significantly enhanced the reversible polarization P_in-max to 0.132 C/m² at the breakdown strength E_b of 600 kV/mm, leading to a high energy density of 21.9 J/cm³ in oriented P(VDF-TrFE-CTFE)/P(VDF-HFP) (50/50 wt%) blended films. The simplicity of the blending approach and the industrial viability of the processing technique, melt-extrusion, combined with high discharged energy density make oriented P(VDF-TrFE-CTFE)/P(VDF-HFP) (50/50 wt%) blended films a potential candidate for advanced energy storage applications.