Scalable polyolefin-based all-organic dielectrics with superior high-temperature capacitive energy storage performance

Polymer dielectrics capable of efficient and stable operation at elevated temperatures (>150 degrees C) are urgently needed to meet the stringent requirements of capacitive energy storage in harsh environments. However, the current leading commercially available polymer dielectric, biaxially oriented polypropylene (BOPP), can only sustain continuous operation at temperatures below 85 degrees C due to its limited thermal stability and significant increase in electrical conduction at high temperatures. Here, we present an all-organic polymer composite comprising nonpolar polyolefin and organic semiconductor that demonstrates superior dielectric and capacitive energy storage performance at 150 degrees C. Notably, the dielectric properties of the polymer composite remain stable across a broad temperature range, exhibiting an ultralow dissipation factor at elevated temperatures. Benefiting from the deep trap energy levels introduced by the organic semiconductor, the composite film achieves one order of magnitude reduction in electrical conductivity. As a result, the composite film attains discharged energy densities of 7.1 J/cm(3) and 5.5 J/cm(3) with a charge-discharge efficiency of 90 % at 25 degrees C and 150 degrees C, respectively. Furthermore, the composite film maintains stable capacitive performance over extended charge-discharge cycles (50,000 cycles) in harsh environments (500 MV/m and 150 degrees C), along with excellent breakdown self-healing capability. These remarkable performances, coupled with the potential for large-scale production using commercially available raw materials, highlight the practically viability of the composite film for high-temperature capacitive energy storage applications.