High Discharge Energy Density and Efficiency in Newly Designed PVDF@SiO₂–PVDF Composites for Energy Capacitors

Abstract

The fabrication of a core–shell structure is an effective method of obtaining a composite film with a high energy density. Herein, we prepared a new type of composite film with high energy density and energy efficiency by using silica-coated core–shells on poly­(vinylidene fluoride) (PVDF) particles that comprised a high proportion of polar phases rather than inorganics with high dielectric constants. We prepared PVDF particles with a high proportion of the β-phase using emulsion polymerization. Subsequently, we prepared PVDF@SiO2 core–shell particles by coating silica using the sol–gel method. The resultant PVDF@SiO2–PVDF exhibited a low reduction in the dielectric constant because of the lower amount of silica than that in other dense silica particles, which was verified through dielectric constant measurements and theoretical calculations. In addition, when the PVDF@SiO2 particle contained 40 wt % silica, a high breakdown strength of 598.95 MV/m was confirmed. Therefore, we verified that the PVDF@SiO2–PVDF composite film has a high discharge energy density of 12.051 J/cm3 when the PVDF@SiO2 is 40 wt %. In addition, the domain size is limited by the silica shell, resulting in a high energy efficiency of 88.22%, which indicated a potential for the utilization of the composite film in energy storage devices. These results offer a novel strategy for the development of polymer-based capacitors with high energy densities and efficiencies.

Significantly Improved Energy Storage Performance of PVDF Ferroelectric Films by Blending PMMA and Filling PCBM

“…To make a more comprehensive comparison of the energy storage properties between inorganic filler/polymer matrix composites and the all-organic composite, relevant studies are shown in Figure . ,− The breakdown strength of the inorganic filler/polymer matrix composites is mostly concentrated below 550 kV mm –1 with a lower energy storage efficiency, as shown in Figure , which is greatly related to the defects generated by the introduction of inorganic fillers. The all-organic composite in this work can effectively avoid the generation of similar defects, achieve a higher breakdown strength, and maintain high efficiency, which makes it have a higher energy storage density although without a higher dielectric constant like inorganic filler/polymer matrix composites.…”

PVDF/Ag2CO3nanocomposites for efficient dye degradation and flexible piezoelectric mechanical energy harvester

“…6 In particular, polymer nanocomposites have been considered as promising candidates to achieve high dielectric constant (3 r ) and electric breakdown strength (E b ), low loss tangent (tan d), easy fabrication process, low cost, and excellent exibility in the advancement of market electronics. [7][8][9][10] In this regard, poly(vinylidene uoride) (PVDF) is a well-known thermoplastic polymer because of its tunable properties such as exibility, robustness, cost-effectiveness and easy processing. Generally, PVDF has 4 different polymorphs, i.e., a-, b-, gand d-phases.…”

Highly Transparent PVDF Films with Enhanced Dielectric and Energy Storage Properties Tailored by a PMMA-co-GMA Copolymer

“…Therefore, dielectric films based on these fluororesins show high discharge energy density. However, the high dielectric loss, remnant polarization, and low charge–discharge efficiency of these films lead to decreased discharge energy density, which limits the application of PVDF in the thin-film capacitor field. − …”