Improved Discharge Energy Density of Poly(vinylidene fluoride)-Based Nanocomposites via a Small Amount of Dopamine-Modified TiO2 Nanosheets

Dielectric capacitors have attracted increasing attention for their fast charge–discharge speeds as well as high power density, and they have been widely used in advanced electronics and electric power systems. Here, dopamine-modified TiO2 (TiO2@PDA) nanosheets were synthesized via hydrothermal reaction and in situ polymerization. Then the synthesized TiO2@PDA nanosheets were introduced into the poly(vinylidene fluoride) (PVDF) matrix via solution blending. Our results reveal that loading a small amount of TiO2@PDA nanosheets can effectively enhance the energy storage performance of the nanocomposites. For example, a superior discharge energy density with 10.53 J/cm3 is obtained for the 9 wt.% TiO2@PDA/PVDF nanocomposite at 195 MV/m, which is 1.75 times as large as discharge energy density of pure PVDF (6.01 J/cm3 at 170 MV/m). Such significant improvement is due to the large aspect ratio as well as dopamine modification of the TiO2 nanosheets. The study provides a feasible way to prepare the nanocomposites with excellent energy storage performance.