Enhancing Energy Density of BaTiO3-Bi(M)O3@SiO2/PVDF Nanocomposites via Filler Component Modulation and Film Structure Design

The low energy density (<i>U</i>_d) of polymeric dielectrics is unfavorable for the integration and miniaturization of electronics, thus limiting their application prospects. Introducing high-<i>ε</i>_r (dielectric constant) ceramic nanofillers to polymer matrices is the most common strategy to enhance their <i>ε</i>_r, and hence their <i>U</i>_d. By comparison, enhancing breakdown strength (<i>E</i>_b) is a more effective strategy to enhance <i>U</i>_d. Herein, 0.6BaTiO₃-0.4Bi(Mg_0.5Ti_0.5)O₃ and 0.85BaTiO₃-0.15Bi(Mg_0.5Zr_0.5)O₃ nanofibers coated with SiO₂ were utilized as fillers in PVDF-based nanocomposites. The combination of experimental and simulation results suggests that the intrinsic properties of nanofillers are the determining factor of the <i>E</i>_b of polymer-based nanocomposites, and SiO₂ coating and film structure design are effective strategies to enhance their <i>E</i>_b, and consequently their <i>U</i>_d. As a result, the sandwich-structured PVDF/6 wt% 0.85BaTiO₃-0.15Bi(Mg_0.5Zr_0.5)O₃@SiO₂ nanofiber within PVDF/PVDF nanocomposite films achieved a maximum <i>U</i>_d of 11.1 J/cm³ at an <i>E</i>_b of 458 MV/m, which are 2.15 and 1.40 times those of pristine PVDF, respectively.