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 degC, 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. The demand for a new generation of high temperature dielectric materials toward capacitive energy storage has been driven by the rise of high power applications such as electric vehicles, aircraft, and pulsed power systems where the power electronics are exposed to elevated temperatures. Polymer dielectrics are characterized by being lightweight, and their scalability, mechanical flexibility, high dielectric strength, and great reliability, but they are limited to relatively low operating temperatures. The existing polymer nanocomposite based dielectrics with a limited energy density at high temperatures also present a major barrier to achieving significant reductions in size and weight of energy devices. Here we report the sandwich structures as an efficient route to high temperature dielectric polymer nanocomposites that simultaneously possess high dielectric constant and low dielectric loss. In contrast to the conventional single layer configuration, the rationally designed sandwich structured polymer nanocomposites are capable of integrating the complementary properties of spatially organized multicomponents in a synergistic fashion to raise dielectric constant, and subsequently greatly improve discharged energy densities while retaining low loss and high charge discharge efficiency at elevated temperatures. At 150 degC and 200 MV m 1, an operating condition toward electric vehicle applications, the sandwich structured polymer nanocomposites outperform the state of the art polymer based dielectrics in terms of energy density, power density, charge discharge efficiency, and cyclability. The excellent dielectric and capacitive properties of the polymer nanocomposites may pave a way for widespread applications in modern electronics and power modules where harsh operating conditions are present.
Proceedings of the National Academy of Sciences