Energy storage in structural composites by introducing CNT fiber/polymer electrolyte interleaves

Area of Science:

• Materials Science
• Electrochemistry
• Composite Materials

Background:

• Developing materials that serve dual roles in structural integrity and energy storage is crucial for advanced applications.
• Existing structural composites often lack integrated energy storage capabilities.
• Carbon fiber composites are widely used for their mechanical properties but not for energy storage.

Purpose of the Study:

• To develop a method for producing structural composites with simultaneous energy storage capabilities.
• To investigate the mechanical and electrochemical performance of these novel materials.
• To explore new architectures for integrated energy storage and structural components.

Main Methods:

• Integrating carbon nanotube (CNT) fiber veils and ionic liquid-based polymer electrolyte between carbon fiber plies.
• Infusing and curing with epoxy resin to form a sandwich structure.
• Conducting in-situ electrochemical measurements during mechanical testing (4-point bending) and synchrotron 3D X-ray tomography.

Main Results:

• The resulting structural supercapacitors exhibit a flexural modulus of 60 GPa and flexural strength of 153 MPa.
• Achieved specific capacitance of 88 mF/g with record power (30 W/kg) and energy (37.5 mWh/kg) densities for structural supercapacitors.
• Electrochemical performance was maintained up to fracture, with epoxy encapsulation protecting the ionic liquid from water.

Conclusions:

• The developed method successfully creates multifunctional structural composites with integrated energy storage.
• These materials offer a promising pathway for lightweight and efficient energy storage solutions in structural components.
• Novel architectures free of current collectors and insulators were demonstrated, utilizing CNT fiber and carbon fiber as active electrodes.