ABSTRACT
Flexible dielectric materials such as poly(vinylidene fluoride)-based nanocomposites with high energy density are employed for applications in modern electronic and electric systems. In this study, we improve traditional methods by optimizing the interfacial structure, achieving a 34% increase in energy density without reduced discharge efficiency. Herein, a simple solution-cast method is used to prepare poly(vinylidene fluoride-co-trifluoroethylene) nanocomposites filled by γ-methacryloyl-propyltrimethoxysilane (MPMS) grafting barium titanate nanoparticles, forming a class of cross-linking networks by irradiation. More additional interfaces arising from irradiation cross-linking give rise to high discharge energy density, and the small crystalline domain and cross-linking network enhance the charge-discharge efficiency. Furthermore, we find two types of cross-linking centers on the network. One is more beneficial to energy density, and the other is more beneficial to efficiency. Regulating two types of cross-linking centers can balance efficiency and energy density. In summary, this work provides a promising strategy for exploiting advanced flexible dielectric materials to meet application requirements.
ABSTRACT
In recent years, high energy density polymer capacitors have attracted a lot of scientific interest due to their potential applications in advanced power systems and electronic devices. Here, core-shell structured TiO2@SrTiO3@polydamine nanowires (TiO2@SrTiO3@PDA NWs) were synthesized via a combination of surface conversion reaction and in-situ polymerization method, and then incorporated into the poly(vinylidene fluoride) (PVDF) matrix. Our results showed that a small amount of TiO2@SrTiO3@PDA NWs can simultaneously enhance the breakdown strength and electric displacement of nanocomposite (NC) films, resulting in improved energy storage capability. The 5 wt% TiO2@SrTiO3@PDA NWs/PVDF NC demonstrates 1.72 times higher maximum discharge energy density compared to pristine PVDF (10.34 J/cm3 at 198 MV/m vs. 6.01 J/cm3 at 170 MV/m). In addition, the NC with 5 wt% TiO2@SrTiO3@PDA NWs also demonstrates an excellent charge-discharge efficiency (69% at 198 MV/m). Enhanced energy storage performance is due to hierarchical interfacial polarization among their multiple interfaces, the large aspect ratio as well as surface modification of the TiO2@SrTiO3 NWs. The results of this study provide guidelines and a foundation for the preparation of the polymer NCs with an outstanding discharge energy density.
