Superior dielectric energy storage performance for high-temperature film capacitors through molecular structure design

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-08, Vol.493, p.152623, Article 152623
• Main Authors: Ding, Song, Jia, Jiangheng, Dai, Zhizhan, Wang, Yiwei, Shen, Shengchun, Yin, Yuewei, Li, Xiaoguang
• Format: Article
• Language: English
• Subjects: Dielectric capacitor; Energy storage; High temperature; Polyimide
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.152623

New polyimides featuring alicyclic structures are designed to improve dielectric energy storage performance. By introducing elongated non-coplanar dicyclohexyl units into the backbones, the electron transport within the intra- and inter-molecular chains is significantly inhibited. This innovation has yielded a record-high discharged energy density of ∼4.9 J/cm3 with ≥95 % efficiency at 150 °C, surpassing other reported dielectric polymers and composites. [Display omitted] •The elongated non-coplanar alicyclic structures reduce dielectric conduction loss.•A record-high energy density of ∼4.9 J/cm3 with η > 95 % is obtained at 150 °C.•Stable cyclability over 100,000 cycles under 400 MV/m at 150 °C is achieved. Film capacitors based on polymer dielectrics face substantial challenges in meeting the requirements of developing harsh environment (≥150 °C) applications. Polyimides have garnered attention as promising dielectric materials for high-temperature film capacitors due to their exceptional heat resistance. However, conventional polyimides with narrow bandgaps suffer from significant conduction loss at high temperatures and high electric fields. Here, we design and synthesize a series of modified polyimides featuring different saturated alicyclic structures on their main chains. Among these, the HBPDA-BAPB polyimide exhibits a superior discharged energy density of 4.9 J/cm3 with a high efficiency exceeding 95 % at 150 °C, outperforming other reported dielectric polymers and composites. The mechanism is attributed to the incorporation of elongated noncoplanar dicyclohexyl units into the backbones, which significantly reduces molecular conjugation, enhances the bandgap and suppresses leakage current. Our findings demonstrate the potential of modified polyimides with alicyclic structures as high-temperature dielectric materials for practical applications.