Poly(ether imide)-Based Nanocomposites with Low Fraction of Hierarchical Ag@AO Nanofiber for High-Temperature Energy Storage

To fabricate the polymer-based nanocomposites with excellent energy storage performances for high-temperature applications, hierarchical x wt % Ag@Al2O3 nanofibers (Ag@AO NFs) are designed and prepared, where various Ag nanoparticles (x wt %) are filled into the Al2O3 nanofibers. By adjusting the weight fraction of Ag nanoparticles, the coupling effects of interfacial polarizations and interfacial barrier at Ag/AO interfaces are explored and optimized; excellent energy storage performance was obtained in the 0.50 wt % Ag@AO/PEI nanocomposite. Owing to the high insulation and high thermal conductivity of Al2O3 nanofibers, a stable energy storage performance is realized within 25–150 °C. For example, the 0.50 wt % Ag@AO/PEI nanocomposite delivers an excellent discharge energy density of 6.1 J/cm3 with charge–discharge efficiency of 89.2% at 413.4 MV/m, which is twice as large as that of the pure PEI (3.0 J/cm3 at 382.4 MV/m, 74.6%). This structural design might provide a feasible solution for realizing enhanced energy storage performance at low filler fraction for high-temperature application.