Sandwich-structured polymer nanocomposites with high energy density and great charge–discharge efficiency at elevated temperatures

Significance Polymers are the materials of choice for high-energy capacitive storage devices due to their inherent advantages such as being lightweight, their ease of processing, and their high dielectric strength. Yet, their performance deteriorates significantly with increasing operating temperature, which falls short of emerging energy applications under harsh conditions. Here we demonstrate the sandwich-structured polymer nanocomposites with greatly improved energy densities, high power densities, and remarkable charge–discharge efficiencies that far exceed those of the existing polymer-based dielectrics at 150 °C, a temperature oriented toward electric vehicle applications. The development of polymer-based dielectric materials capable of high-temperature operation represents a key element in meeting the technological challenges and fulfilling the requirements of advanced electronics and electrical power systems.