Role of Microstructures in the Dielectric Properties of PVDF-Based Nanocomposites Containing High-Permittivity Fillers for Energy Storage

Abstract

Polymer-based nanocomposites containing inorganic ferroelectric inclusions, typically ABO3 perovskites, have emerged as innovative dielectric materials for energy storage and electric insulation, potentially coupling the high breakdown strength (BDS) and easy processing of polymers with the enhancement of dielectric constant provided by the ferroelectric phase. In this paper, experimental data and three-dimensional finite element method (3D FEM) simulations were combined to shed some light on the effect of microstructures on the dielectric properties of poly(vinylidene fluoride) (PVDF)-BaTiO3 composites. The existence of particle aggregates or touching particles has a strong effect on the effective dielectric constant and determines an increase of the local field in the neck region of the ferroelectric phase with a detrimental effect on the BDS. The distribution of the field and the effective permittivity are very sensitive to the specific microstructure considered. The degradation of the BDS can be overcome by coating the ferroelectric particles with a thin shell of an insulating oxide with a low dielectric constant, such as SiO2 (εr = 4). The local field is highly concentrated on the shell, while the field in the ferroelectric phase is reduced almost to zero and that on the matrix is close to the applied one. The electric field in the matrix becomes less homogeneous with increasing the dielectric constant of the shell material, as happens with TiO2 (εr = 30). These results provide a solid background to explain the enhanced dielectric properties and the superior BDS of composites containing core–shell inclusions.

Enhanced Energy Storage Performance of Doped Modified PC/PVDF Coblended Flexible Composite Films

“…The SEM image of the TiO 2 particle agglomerates is shown in Figure S5, which shows the agglomerates with diameters of about 200 nm. It has been shown that due to the principle of incompatibility at the organic\inorganic interface, the mass accumulation of inorganic fillers causes significant structural defects at the organic/inorganic interface of the hybrid film, resulting in considerably decreased insulation capability, which will eventually reduce the ability of the combined material to store energy. − …”

CsPbI3–PVDF Composite-Based Multimode Hybrid Piezo-Triboelectric Nanogenerator: Self-Powered Moisture Monitoring System

“…The polarization in the PVDF matrix gradually increases with increasing filler loading up to 5 wt % and then decreases dramatically for filler quantities greater than 5 wt %. The addition of more CsPbI 3 to the composite promotes interactions among themselves, resulting in percolative pathways, and after a certain wt % of CsPbI 3 (>5 wt %), the loop area decreases. − …”

Morphological engineering of SiO2 interlayer towards meliorative dielectric and thermal properties in β‐SiCw@SiO2/PVDF composites

“…5,19 Therefore, this kind of core@shell structured particle is regarded as the good strategy for accomplishing the balance between the high ε and E b as well as low loss in polymers. [20][21][22][23][24] As one kind of one-dimensional semiconductor nanomaterials, β-silicon carbide whiskers (β-SiC w ) with a large aspect ratio and excellent overall properties like high mechanical modulus and strength, as well as large TC had been widely used in various occasions. 25,26 Upon approaching the f c , the β-SiC w /polymers exhibit a concurrent increase in both the ε and TC, which are unfortunately accompanied with the appearance of leakage current and a large loss.…”

“…Besides, the insulating shells like dielectric ceramics with a medium ε usually covering on the fillers' superficies can effectively assuage the permittivity mismatch between the matrix and the filler, thus lessening the maldistribution electric field or distortion throughout the composites, thus enhancing high‐field endurance 5,19 . Therefore, this kind of core @ shell structured particle is regarded as the good strategy for accomplishing the balance between the high ε and E b as well as low loss in polymers 20–24 …”