Reduced Polyaniline-Modified NaNbO3 Nanowire/Polyetherimide Nanocomposites for Dielectric Capacitors with Enhanced Dielectric Properties and High Thermal Stability

The development of high-performance antiferroelectric ceramics/polymeric materials with great thermal stability has attracted considerable interest due to their extensive use in efficient power sources and electronic devices. Nevertheless, the high energy storage density and thermal stability of dielectrics are seriously restricted due to their poor processibility and weakened breakdown strength (Eb). To resolve these tough issues, it would be highly effective and feasible if an organically modified high-aspect-ratio one-dimensional (1D) antiferroelectric ceramic can be employed. Specifically, the 1D nanofiller can extend the breakdown path and improve the local electric field distribution while the organic modification endows dielectrics with enhanced interface polarization and improved compatibility, thus yielding high energy storage density. Herein, a series of high-aspect-ratio 1D NaNbO3 nanofiller with organic insulating reduced polyaniline (R-PANI) layer are synthesized by the oxidative polymerization and then introduced into the polyetherimide (PEI) matrix. The prepared NaNbO3@R-PANI/PEI nanocomposites possess enhanced dielectric constant up to 9.8 as well as ultralow dielectric loss (0.009) while maintaining the high energy density of 2.46 J/cm3 (1.4 times of that for pure PEI) and high efficiency of 82.6% at 200 MV/m at a small loading of 3 vol %. Depending on the unique structure of the coated R-PANI, the 3 vol % NaNbO3@R-PANI/PEI increased the energy density up to 4.4 J/cm3 and maintained high efficiency of 70.9% at 200 MV/m under 150 °C, therefore making it a potential candidate for polymeric dielectric materials used in extreme environments.