Polyimides Physically Crosslinked by Aromatic Molecules Exhibit Ultrahigh Energy Density at 200 °C

Area of Science:

• Materials Science
• Polymer Chemistry
• Electrostatics

Background:

• Polymer dielectrics are crucial for electrostatic energy storage, but their performance, particularly discharged energy density (U_d), degrades at high temperatures due to reduced breakdown strength (E_b) and efficiency (η).
• Existing strategies like inorganic incorporation and crosslinking to enhance U_d often compromise flexibility, interfacial properties, or involve complex synthesis.

Purpose of the Study:

• To develop an effective strategy for improving the high-temperature electrostatic energy storage performance of polymer dielectrics.
• To address the limitations of current enhancement methods by creating a novel all-organic composite system.

Main Methods:

• Incorporation of 3D rigid aromatic molecules into aromatic polyimides to create physical crosslinking networks via electrostatic interactions.
• Characterization of the resulting polyimide composites for their dielectric properties, including breakdown strength, efficiency, and energy density at elevated temperatures.
• Evaluation of charge carrier trapping mechanisms and long-term stability under harsh operating conditions.

Main Results:

• The introduction of 3D rigid aromatic molecules formed dense physical crosslinking networks, enhancing polyimide strength and boosting breakdown strength (E_b).
• The aromatic molecules effectively trapped charge carriers, suppressing energy loss and improving overall efficiency (η).
• Achieved ultrahigh discharged energy densities (U_d) of 8.05 J cm^-3 at 150°C and 5.12 J cm^-3 at 200°C.
• Demonstrated stable performance over 10⁵ charge-discharge cycles in harsh environments (500 MV m^-1, 200°C).

Conclusions:

• The developed strategy effectively combines the benefits of inorganic incorporation and crosslinking using an all-organic approach.
• This method significantly enhances the high-temperature electrostatic energy storage capabilities of aromatic polyimides, offering a promising alternative to conventional techniques.
• The material exhibits excellent durability and potential for large-scale preparation, paving the way for advanced energy storage applications.