Nanoscale phase separation achieved through trace PVDF/PEI blending enhances mechanical and energy storage performance at high temperatures

• Published in: Journal of power sources 2024-11, Vol.620, p.235255, Article 235255
• Main Authors: Zhang, Tianran, Shi, Bofeng, Zhang, Siyu, Song, Mengfan, Wang, Jiping, Zhang, Lixue, Kang, Fang
• Format: Article
• Language: English
• Subjects: All-organic composites; Dielectric energy storage; High temperature; Mechanical property; Phase separation
• ISSN: 0378-7753
• DOI: 10.1016/j.jpowsour.2024.235255

Due to the development of advanced electronic systems, there is an urgent need for polymer dielectric film capacitors with high breakdown strength (Eb) and high discharge energy density (Ud) at elevated temperatures. Herein, an all-organic blend polymer composite is fabricated by blending polyetherimide (PEI) and a trace amount of Poly(vinylidene fluoride) (PVDF), achieving nanoscale phase separation and forming interfaces between PEI and PVDF grain. The real permittivity (εr) and Eb of blend composites are simultaneously enhanced after PVDF introduction. It is worth noting that increasing the temperature does not reduce the Eb of the PEI/xPVDF blend composite. Our Study shows that optimizing the plasticity and storage modulus of PEI/xPVDF significantly contributes to maintaining Eb at elevated temperatures. Additionally, high temperatures enhance the entanglement of molecular chains at the PVDF-PEI interface, further supporting the preservation of Eb. Finally, a high Eb of 540 MV/m, a high Ud of 5.92 J/cm3 are achieved for the PEI/0.5PVDF blend at 150 °C. This work presents a new approach to enhance the Eb of dielectric polymers by optimizing mechanical properties at high temperature, which providing a different strategy for enhancing the energy storage performance. [Display omitted] •A trace of PVDF in PEI results in nanoscale phase separation.•Nanoscale phase separation optimizes Eb and polarization simultaneously.•At 150 °C, PEI/0.5PVDF has an Eb of 540 MV/m and a Ud of 4.12 J/cm³ with η > 90 %.