Metallized stacked polymer film capacitors for high-temperature capacitive energy storage

Metallized film capacitors towards capacitive energy storage at elevated temperatures and electric field extremes call for high-temperature polymer dielectrics with high glass transition temperature (T-g), large bandgap (E-g), and concurrently excellent self-healing ability. However, traditional high-temperature polymers possess conjugate nature and high S value (C/(H + O) ratio), which compromises E-g and self-healing properties. Herein, we provide a series of novel molecules-fully alicyclic polymers based on commercial Kapton PI (Al-PIs), which exhibit intrinsic decoupling conjugate and decreasing S, leading to high E-g and robust self-healing. The Al-PIs possess much increased E-g of 5.23 eV (T-g of 242 degrees C) or E-g of 5.01 eV (T-g of 280 degrees C) with a lowered S < 0.7, which approaches E-g of 5.93 eV and S of 0.5 for the commercial benchmark biaxially oriented polypropylene (BOPP) applied at low temperatures (<= 70 degrees C). Consequently, Al-PI delivers a record discharge energy density with 90 % discharge efficiency (U-eta 90) of up to 8.04 J/cm(3) at 150 degrees C, 5.74 J/cm(3) at 200 degrees C, and 3.12 J/cm(3) at 250 degrees C, respectively. Besides, Al-PI is capable of self-healing even at 200 degrees C. We also demonstrate a stacked Al-PI metallized film capacitor with discharge energy density up to 1.6 J/cm(3) and discharge efficiency of 98 % at 150 degrees C. These results confirm that alicyclic polymers are promising candidates for high-performance dielectric films and capacitors under extreme thermal and electric field conditions.