Improvement of high‐temperature energy storage properties of polyimide‐based nanocomposites with sandwich structure

Abstract The demand for dielectric materials that have high energy and power density properties, and are operational at high temperature has increased with the advancement in new energy technology, high‐end microelectronics, and other industries. Pure ceramic and polymer capacitors are not enough to meet the ever increasing energy requirements in a wide range of applications. In this article, we report a sandwich structure nanocomposite film based on polyimide (PI) with high breakdown strength SiO 2 /PI as the outer layers and high dielectric constant strontium titanate (SrTiO 3 )/PI as the sandwich layer. The results showed that the prepared composites can obtain high energy storage density and low dielectric loss at high temperatures. The composites achieved an energy storage density of 5.5 J cm −3 and a dielectric loss of 0.004 at a temperature of 150°C when the filling amount of SrTiO 3 was 0.5 vol% and the filling amount of SiO 2 was 3 vol%. This work shows that the composites are promising dielectrics for applications at high temperature and provides a new idea for high‐temperature energy storage devices.