Abstract
A high recoverable energy storage density polymer composite film has been designed in which the ferroelectric-paraelectric 0.85 (K0.5Na0.5NbO3)-0.15SrTiO3 (abbreviated as KNN-ST) solid solution particles were introduced into polyvinylidene fluoride (PVDF) polymer as functional fillers. The effects of the polarization properties of K0.5Na0.5NbO3 (KNN) and KNN-ST particles on the energy storage performances of KNN-ST/PVDF film were systemically studied. And the introduction of SrTiO3 (ST) was effective in reducing the remnant polarization of the particles, improving the dielectric properties and recoverable energy storage density of the KNN-ST/PVDF films. Compared to KNN/PVDF films, the dielectric permittivity of composite films was enhanced from 17 to 38 upon the introduction of ST. A recoverable energy storage density of 1.34 J/cm3 was achieved, which is 202.60% larger than that of the KNN/PVDF composite films. The interface between the particles and the polymer matrix was considered to the enhanced dielectric permittivity of the films. And the reduced remnant polarization of the composites was regarded as the improving high recoverable energy storage density. The results demonstrated that combing ferroelectric- paraelectric particles with polymers might be a key method for composites with excellent dielectric permittivity, high energy storage density, and energy efficiency.
Highlights
Polymeric composites with high energy density have been attracting increasing attention in recent years, which possess both the outstanding dielectric properties of selected functional inorganic fillers and the high breakdown strength, machinability, and mechanical performance of the polymer matrix
1.34 J/cm3 was obtained in the polyvinylidene fluoride (PVDF) composite film with 12 vol% KNN-ST, and the maximal energy storage efficiency of 74.68% was obtained in 3 vol% KNN-ST/PVDF composite films
The results illustrate that KNN-ST/PVDF composite films have have higher higher breakdown composite films
Summary
Polymeric composites with high energy density have been attracting increasing attention in recent years, which possess both the outstanding dielectric properties of selected functional inorganic fillers and the high breakdown strength, machinability, and mechanical performance of the polymer matrix. Previous work has successfully increased recoverable energy storage density, the low energy efficiency and high losses are still the critical restrictions for composites This problem can be ascribed to two reasons: one is the interfacial polarization caused by the significant difference in dielectric constant and conductivity between the polymer matrix and the fillers [15]. 1.34 J/cm was obtained in the PVDF composite film with 12 vol% KNN-ST, and the maximal energy storage efficiency of 74.68% was obtained in 3 vol% KNN-ST/PVDF composite films
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