Three-layer structure design for enhancing the energy efficiency and breakdown strength of KTaNbO/polyimide nanocomposite films with high thermal stability.

Most polymers used as energy storage have a low operating temperature that limits the broad applications of capacitors. In this paper, PI was used as the polymer matrix, which endowed the KTN/PI composite film with an ultrahigh thermal decomposition temperature (~550 °C). In the designed three-layer-structured KTN/PI composite films, pure PI is employed as a middle layer while KTN nanoparticles are introduced in two outer layers. It is found that the three-layer-structured KTN/PI composite film could achieve a higher energy density (3.0 J/cm) than the single-layer-structured KTN/PI composite film (1.5 J/cm) by modulating distribution of its local electric field. The three-layer structure has been proved to be quite effective in enhancing the composite films' breakdown strength and increasing their energy density and discharge efficiency. [ABSTRACT FROM AUTHOR]