Excellent dielectric energy storage performance achieved by synergistically increasing the permittivity and breakdown strength of poly(vinylidene chloride-co-vinyl chloride) with a stabilized conformation

Abstract

Achieving high-energy-density polymer dielectrics often involves a trade-off between enhanced permittivity and superior breakdown strength, which limits the miniaturization and integration of thin-film capacitors. In this work, to address this issue, a dipole regulation strategy was employed to fabricate a polar semi-crystalline poly(vinylidene chloride-co-vinyl chloride) (P(VDC-VC)) film. The study demonstrates that the large volume and significant steric hindrance of chlorine atoms endow P(VDC-VC) with high conformational transition barriers, enabling it to maintain a stable TGTG′ conformation and an α-crystal phase under high electric fields. At 1 kHz, P(VDC-VC) exhibits a dielectric constant of 5.1, which is higher than that of most linear dielectrics reported in the literature. Additionally, the stable conformation ensures robust polarization capability and low dielectric loss under high electric fields. The well-organized crystalline regions and the electron–hole trapping ability further reduce the leakage current of the P(VDC-VC) film, achieving a breakdown strength of up to 780 MV m⁻¹. This work successfully decouples the trade-off between high permittivity and elevated breakdown strength via dipole regulation, offering an effective approach and theoretical guidance for the design of high-performance polymer dielectrics.