Stepwise Molecular Design of Epoxy Dielectric Films toward High-Temperature, High-Efficiency Energy Storage

Area of Science:

• Materials Science
• Polymer Chemistry
• Electrical Engineering

Background:

• Growing demand for high-power electronics in electric vehicles and renewable energy converters requires dielectric films with high energy density and efficiency at elevated temperatures.
• Current biaxially oriented polypropylene (BOPP) films have limited operating temperatures, hindering their use in harsh environments.

Purpose of the Study:

• To develop novel epoxy dielectric films capable of high-temperature energy storage.
• To establish a molecular design strategy for balancing thermal stability, polarization, and dielectric loss.
• To provide guidance for creating advanced high-temperature dielectric materials.

Main Methods:

• Stepwise molecular design of epoxy dielectric films.
• Introduction of a sulfone-containing curing agent for improved high-temperature efficiency.
• Tuning resin functionality with a tetrafunctional epoxy to enhance thermal operating window.
• Incorporation of hydrogenated epoxy to disrupt microstructural organization and reduce dielectric loss.

Main Results:

• Optimized epoxy films achieve 4.3 J/cm³ energy density at 200°C.
• Dielectric efficiency remains above 90% at elevated temperatures.
• High-field loss behavior, not just glass transition temperature (Tg), dictates efficiency at high temperatures.

Conclusions:

• A stepwise molecular design framework effectively links material structure to dielectric performance.
• The developed epoxy films show significant potential for high-temperature energy storage applications.
• This approach offers a pathway for designing next-generation dielectric materials for demanding electronic systems.