Significantly Enhanced Energy Density by Tailoring the Interface in Hierarchically Structured TiO₂–BaTiO₃–TiO₂ Nanofillers in PVDF-Based Thin-Film Polymer Nanocomposites

Abstract

Dielectric polymer nanocomposites with a high breakdown field and high dielectric constant have drawn significant attention in modern electrical and electronic industries due to their potential applications in dielectric and energy storage systems. The interfaces of the nanomaterials play a significant role in improving the dielectric performance of polymer nanocomposites. In this work, polydopamine (dopa)-functionalized TiO2–BaTiO3–TiO2 (TiO2–BT–TiO2@dopa) core@double-shell nanoparticles have been developed as novel nanofillers for high-energy-density capacitor applications. The hierarchically designed nanofillers help in tailoring the interfaces surrounding the polymer matrix as well as act as individual capacitors in which the core and outer TiO2 shell function as a capacitor plate because of their high electrical conductivity while the middle BT layer functions as a dielectric medium due to high dielectric constant. Detailed electrical characterizations have revealed that TiO2–BT–TiO2@dopa/poly­(vinylidene fluoride) (PVDF) possesses a higher relative dielectric permittivity (εr), breakdown strength (E b), and energy density as compared to those of PVDF, TiO2/PVDF, TiO2@dopa/PVDF, and TiO2–BT@dopa/PVDF polymer nanocomposites. The εr and energy density of TiO2–BT–TiO2@dopa/PVDF were 12.6 at 1 kHz and 4.4 J cm–3 at 3128 kV cm–1, respectively, which were comparatively much higher than those of commercially available biaxially oriented polypropylene having εr of 2.2 and the energy density of 1.2 J cm–3 at a much higher electric field of 6400 kV cm–1. It is expected that these results will further open new avenues for the design of novel architecture for high-performance polymer nanocomposite-based capacitors having core@multishell nanofillers with tailored interfaces.

Enhanced energy density of PVDF-based nanocomposites via a core–shell strategy

“…Table 2 summarizes the energy storage performance of TiO 2 @SrTiO 3 @PDA NWs/PVDF NC and some previously reported dielectric NCs. It can be observed that the NCs in this study exhibit comparable or higher discharge energy density than that of previously reported dielectric NC films 16,[47][48][49][50][51][52][53][54][55][56][57] . High discharge energy density is due to the additional interfacial polarization induced in the interfacial region of TiO 2 @SrTiO 3 NWs and high permittivity and low remnant polarization of paraelectric ceramic SrTiO 3 shell.…”

The search for enhanced dielectric strength of polymer‐based dielectrics: A focused review on polymer nanocomposites

“…However, the dielectric loss is higher than in the neat polymer matrix, and the dielectric strength of the neat polymer reference is quite low. [ 189,190 ]…”

Interface modulation in multi-layered BaTiO3 nanofibers/PVDF using the PVP linker layer as an adhesive for high energy density capacitor applications

“…The sharp peaks at 1435 and in the range of 400-850 cm À1 represent Ti-O stretching. 6,26,27 The small doublet peaks at 2923 and 2854 cm À1 are assigned to asymmetric and symmetric -CH 2 vibrations, respectively. 28 This confirms the successful synthesis of BT NFs to be used as nanofillers in capacitor devices.…”

“…An ideal dielectric should exhibit a high dielectric constant (e r ) or polarization (P) as well as high breakdown strength (E b ) for high energy density (U d ), as given by eqn (1), 6 U…”

“…5 , which makes it highly challenging to select the best nanofillers as well as polymers for high energy density. 6 Researchers have used different nanofillers such as barium titanate (BT), titanium dioxide (TiO 2 ), etc. of different aspect ratios including 0-dimensional (e.g.…”