Remarkably Boosted High‐Temperature Electrostatic Energy Storage of Polyetherimide Film Induced by TiO2@Au@AlOx@Au Core‐shell Nanofibers

Abstract Polymer dielectrics have broad applications in advanced electronics and power systems. However, they suffer from low energy density and poor breakdown performance at high temperatures, limiting their applications in high‐temperature environments. Herein, TiO 2 @Au@AlO x @Au nanofibers with double coulomb blockade nanolayers are obtained via a physical sputtering strategy to improve the high‐temperature energy storage performance of polyetherimide composites. Experimental studies and finite elemenet phase‐field simulations demonstrate that the double‐layer coulomb blockade effect and micro‐capacitor effect of Au nanoparticles synergistically enhance the breakdown strength and dielectric permittivity of polyetherimide composite at high temperatures. Notably, the composite exhibits ultra‐high discharged energy densities of 11.33 and 9.70 J cm −3 at 150 and 200 °C, respectively, along with high charge–discharge efficiencies of 93.4% and 84%, which far exceed that of the polymer nanocomposites reported so far. Furthermore, the composite exhibits excellent charge–discharge cycling performance (>50000 cycles at 400 MV m −1 ) and high‐power density (1.16 MW cm −3 ) at 200 °C, making it an ideal candidate for high‐temperature capacitors. Hopefully, these nanofibers not only serve as excellent nanofillers for high‐temperature energy storage dielectric composites but also holds tremendous potential and inspirational significance for other applications such as electronics, biomedical fields, optics, and catalysis.