Recent progress in polymer dielectric energy storage: From film fabrication and modification to capacitor performance and application

Polymer-based film capacitors have attracted increasing attention due to the rapid development of new energy vehicles, high-voltage transmission, electromagnetic catapults, and household electrical appliances. In recent years, all-organic polymers, polymer nanocomposites, and multilayer films have proposed to address the inverse relationship between dielectric constant and electric breakdown strength, reduce the polarization loss and high-temperature conduction loss of polymer dielectric films. This review aims to provide a comprehensive summary of polymer dielectric films and capacitors in recent years. We compare and summarize the pros and cons of film fabrication and electric energy storage testing methods, and the representative advanced techniques recently used for refined structure characterization are also introduced. The modification methods used to improve room-temperature energy storage performance of polymer films are detailedly reviewed in categories. Additionally, this review studies the high-temperature energy storage of polymer films from three perspectives: molecular modification, doping engineering and multilayer design. To bridge the gap between fundamental research in the lab and the requirements of capacitor industry, the manufacturing, performance evaluation index, monitoring conditions of film capacitors are systematically analyzed, which is very significant to develop high-performance polymer dielectric films. Finally, the challenges and future developments are proposed at the end of this review.