Sandwiched Polymer Nanocomposites Reinforced by Two-Dimensional Interface Nanocoating for Ultrahigh Energy Storage Performance at Elevated Temperatures.

Polymer-based dielectrics are essential components in electrical and power electronic systems for high power density storage and conversion. A mounting challenge for polymer dielectrics is how to maintain their electrical insulation at not only high electric fields but also elevated temperatures, in order to meet the growing needs for renewable energies and grand electrifications. Here, a sandwiched barium titanate/polyamideimide nanocomposite with reinforced interfaces via two-dimensional nanocoatings is presented. It is demonstrated that boron nitride and montmorillonite nanocoatings can block and dissipate injected charges, respectively, to present a synergetic effect on the suppression of conduction loss and the enhancement of breakdown strength. Ultrahigh energy densities of 2.6, 1.8, and 1.0 J cm-3 are obtained at 150 °C, 200 °C, and 250 °C, respectively, with a charge-discharge efficiency >90%, far outperforming the state-of-the-art high-temperature polymer dielectrics. Cyclic charge-discharge tests up to 10 000 times verify the excellent lifetime of the interface-reinforced sandwiched polymer nanocomposite. This work provides a new pathway to design high-performance polymer dielectrics for high-temperature energy storage via interfacial engineering.

Interfacial 2D Montmorillonite Nanocoatings Enable Sandwiched Polymer Nanocomposites to Exhibit Ultrahigh Capacitive Energy Storage Performance at Elevated Temperatures.

Polymer dielectrics are essential for advanced electrical and electronic power systems due to their ultrafast charge-discharge rate. However, a long-standing challenge is to maintain their dielectric performance at high temperatures. Here, a layered barium titanate/polyamideimide nanocomposite reinforced with rationally designed interfaces is reported for high-temperature high-energy-density dielectrics. Nanocoatings composed of 2D montmorillonite nanosheets with anisotropic conductivities are interposed at two kinds of macroscopic interfaces: 1) the interfaces between adjacent layers in the nanocomposites (inside) and 2) the interfaces between the surface of the nanocomposite and the electrode (outside). By revealing the charge transport behavior with Kelvin probe force microscope, surface potential decay, and finite element simulation, it is demonstrated that the outside nanocoatings are observed to diminish charge injection from the electrode, while the inside nanocoatings can suppress the kinetic energy of hot carriers by redirecting their transport. In this interface-reinforced nanocomposite, an ultrahigh energy density of 2.48 J cm-3 , as well as a remarkable charge-discharge efficiency >80%, is achieved at 200 °C, six times higher than that of the nanocomposite without interfacial nanocoatings. This research unveils a novel approach for the structural design of polymer nanocomposites based on engineered interfaces to achieve high-efficient and high-temperature capacitive energy storage.