Sandwich-structured polymer dielectric composite films for improving breakdown strength and energy density at high temperature

• Published in: Composites science and technology 2022-08, Vol.227, p.109596, Article 109596
• Main Authors: Zhang, Tianran, Sun, Qinzhao, Kang, Fang, Wang, Zepeng, Xue, Rong, Wang, Jiping, Zhang, Lixue
• Format: Article
• Language: English
• Subjects: All-organic composites; Dielectric energy storage; Electric field distribution; High temperature; Sandwich-structured materials
• ISSN: 0266-3538; 1879-1050
• DOI: 10.1016/j.compscitech.2022.109596

Polymer dielectric capacitor have attracted much attention in the field of electronic power systems recently due to high power density and high breakdown strength. However, with the development of miniaturization and integration, further demands have been set on the higher energy storage density as well as better temperature resistance for dielectric polymers. Up to now, hierarchical structure provides an effective way to meet these requirements. Herein, we report a sandwich-structured all-organic composite via inserting polymethyl methacrylate/poly(vinylidene fluoride) (PMMA/PVDF) blend layer into polyetherimide layers. Increasing temperature increases the permittivity of the middle layer and the addition of PMMA makes the permittivity increase faster with temperature than pure PVDF middle layer. The capacitor series model and finite element simulation confirmed that the change of the middle layer permittivity realized the electric field redistribution to self-adapt to the temperature, preventing premature breakdown at elevated temperature. At 100 °C, optimized composite exhibits a high breakdown strength of 486.05 MV/m along with high polarization. Eventually, a high discharge energy density of 8.65 J/cm3 is obtained, which is 229.44% of pure PEI. The high polarization at high temperature was realized by utilizing the permittivity of PMMA/PVDF rising with temperature, thereby increasing the energy density at elevated temperature. [Display omitted] •Self-adaptive temperature capability of electric field distribution was achieved.•High breakdown strength and high polarization were simultaneously obtained at 100 °C.•Efficiency of 72.12% and energy density of 8.65 J/cm3 were obtained at 100 °C.