Investigation on the dielectric performance of PVDF-HFP/LZO composites

Abstract

The energy storage density of the film capacitor is crucial for optoelectronic devices. Among various dielectrics, polyvinylidene-fluoride-co-hexafluoropropylene (PVDF-HFP) copolymer is widely preferred due to its inherent high dielectric constant and breakdown strength. However, the low energy storage density and high dielectric loss (tan δ) of PVDF-HFP remains challenging in the present scenario. In this work, we demonstrated how to improve the dielectric constant and energy density of PVDF-HFP with low dielectric losses by formulating PVDF-HFP/Lanthanum Zirconium Oxide (LZO) composite ink at low temperature. We performed the computational modeling of the thin-film capacitor, consisting of PVDF-HFP/LZO as a dielectric layer, to find the optimum LZO content for achieving a high energy density. A computational model of the film capacitor and dielectric shielding was built with PVDF-HFP/LZO composites having a different LZO content to understand its effect on the electric field distribution, polarization, and energy storage density. We compared the dielectric properties of the PVDF-HFP/LZO thin-film capacitor predicted by simulations with the experimental values measured by impedance analysis. The optimum LZO content in PVDF-HFP was determined as 15 vol% to achieve a high energy storage density of 15.8 J/cm3 at 545 MV/m breakdown strength with low dielectric losses. Dielectric constant and energy storage density of the PVDF-HFP/LZO15 composite film were nearly doubled compared to that of neat PVDF-HFP by keeping dielectric losses low. © 2020 Elsevier B.V.