Crosslinked P(VDF‐CTFE)/PS‐COOH nanocomposites for high‐energy‐density capacitor application

• Published in: Journal of polymer science. Part B, Polymer physics Vol. 54; no. 12; pp. 1160 - 1169
• Main Authors: Chen, Yingxin, Tang, Xin, Shu, Jie, Wang, Xiaoliang, Hu, Wenbing, Shen, Qun-Dong
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley 15.06.2016; Blackwell Publishing Ltd; Wiley Subscription Services, Inc
• Subjects: Capacitors; carboxylic polystyrene nanoparticles; Cross polarization; crosslinked nanocomposites; Crosslinking; dielectric permittivity; Electric fields; Energy density; Excitation; high-power-density capacitor; Nanocomposites; Nanoparticles; poly(vinylidene fluoride-chlorotrifluoroethylene)
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/polb.24023

High‐capacity or high‐power‐density capacitors are being actively investigated for portable electronics, electric vehicles, and electric power systems. The dielectric nanocomposite with a small loading of carboxylic polystyrene (PS‐COOH) nanoparticles in poly(vinylidene fluoride‐chlorotrifluoroethylene) [P(VDF‐CTFE)] matrix, followed by chemical crosslinking has been described. Combination of these two methods significantly improved the capacity of electric energy storage at low electric field. Specially, the nanocomposite with 2 wt % nanoparticles and 15 wt % crosslinking agent achieved a dielectric constant of 17.2 and a discharged energy density of 17.5 J/cm³ (4.9 Wh/L) at an electric field as high as 324 MV/m, while corresponding values for pristine P(VDF‐CTFE) are 9.6 and 13.3 J/cm³ (3.7 Wh/L), respectively. Fundamental physics underlying the enhancement in the performance of the nanocomposites with respect to P(VDF‐CTFE) is illustrated by solid‐state ¹⁹F nuclear magnetic resonance of direct excitation or ¹⁹F{¹H} cross polarization. It revealed different dynamics behavior between crystalline/amorphous regions, and PS‐COOH nanoparticles favored the formation of polar γ‐form crystals. Small‐angle X‐ray scattering studies revealed the contribution of the interface to the extraordinary storage of electric energies in the nanocomposites. This approach provided a facile and straightforward way to design or understand PVDF‐based polymers for their practical applications in high‐energy‐density capacitors. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1160–1169