Document Type

Article

Publication Date

12-1-2025

Abstract

Biaxially oriented polypropylene (BOPP) films are widely used in dielectric capacitors due to their ultralow loss, high breakdown strength, and long lifetime. However, their poor temperature tolerance limits applications in emerging high-temperature environments such as wide-band-gap power electronics in electric vehicles. Here, we report significantly enhanced dielectric insulation properties of biaxially oriented poly(ethylene 2,6-naphthalate) (BOPEN) films compared to biaxially oriented poly(ethylene terephthalate) (BOPET) films, despite their similar semicrystalline morphologies. BOPEN exhibits higher DC and AC breakdown strengths and markedly extended lifetimes at elevated temperatures. For instance, at 120 °C, the DC Weibull lifetime of BOPEN exceeded that of BOPET by over two orders of magnitude and even surpassed that of BOPP. Through comprehensive analyses—leakage current, electric displacement-electric field loops, and thermally stimulated depolarization current—we attribute this superior performance to suppressed homocharge injection and conduction losses, enabled by the rigid naphthalene-based backbone in BOPEN that reduces dipole mobility and chain polarity. These findings underscore the potential of BOPEN as a next-generation polymer dielectric for high-temperature capacitor applications.

Keywords

AC electronic conduction, DC electronic conduction, dielectric insulation, homocharge injection, poly(ethylene 2, 6-naphthalate), poly(ethylene terephthalate)

Language

English

Publication Title

Energy Storage Materials

Grant

N00014-23-1-2788

Rights

© 2025 The Author(s). This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/), which permits non-commercial copying and redistribution of the material in any medium or format, provided the original work is not changed in any way and is properly cited.

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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