Structural Supercapacitor Composites for Energy Storage

Structural supercapacitor composites represent a class of multifunctional materials designed to carry mechanical loads while simultaneously storing and delivering electrical energy. By integrating high-surface-area electrodes, conductive fibres and solid or gel electrolytes within a load-bearing matrix, these systems offer a lightweighting strategy for electric vehicles, drones and aerospace structures where every gram matters. Key developments have centred on carbon-based reinforcements such as carbon fibres, carbon nanotubes and graphene, which serve as both mechanical reinforcement and active electrode. Architectural approaches include interleaving thin electrode–electrolyte layers between plies of composite laminates, surface functionalisation or grafting of redox-active groups onto fibres, and direct growth of nanocarbon networks on fibre surfaces. Performance metrics such as tensile and flexural modulus (up to tens of gigapascals), specific capacitance (from tens to hundreds of millifarads per gram), energy density (whilst remaining lower than batteries, often exceeding conventional capacitors in power density) and long-term cycling stability under mechanical strain are central to evaluating functionality. Current challenges revolve around balancing electrochemical performance with mechanical integrity, ensuring interlaminar adhesion, developing processable solid electrolytes and devising scalable manufacturing routes to realise compact, structurally efficient energy-storing components.

Research from Nature Portfolio

Recent studies have introduced high-strength polymeric solid electrolytes that support load-bearing/energy-storage integration into electrochemical capacitors with flexural modulus around 18 GPa and flexural strength near 160 MPa, while delivering specific capacitances of 32 mF cm⁻², energy densities of 0.13 Wh m⁻² and peak power densities of 1.3 W m⁻²; multilayered device architectures further improve mechanical resilience and allow bending, secondary machining and assembly without degradation of energy storage. Foundational work has demonstrated the embedding of thin sandwich structures of carbon nanotube-fibre veils and ionic liquid-based polymer electrolyte between carbon fibre plies followed by epoxy infusion, resulting in composites that exhibit both electric double-layer capacitor behaviour (88 mF g⁻¹) and high flexural modulus (60 GPa) with flexural strength of 153 MPa, alongside power densities of 30 W kg⁻¹ and energy densities reaching 37.5 mWh kg⁻¹; advanced grid-shaped interleaves and current-collector-free architectures preserve electrochemical performance under mechanical stress and in aqueous environments.

Structural Supercapacitor Composites for Energy Storage publication trend

The graph below shows the total number of articles in structural supercapacitor composites for energy storage across all publications each year (not limited to Nature Index journals).

Technical terms

Structural supercapacitor composite: A multifunctional material that simultaneously bears mechanical loads and stores electrical energy through electrostatic charge separation.

Specific capacitance: The electric charge storage capacity per unit mass (F g⁻¹) of the active electrode materials.

Energy density: The amount of energy stored per unit mass (Wh kg⁻¹) or unit area (Wh m⁻²) of the composite device.

Power density: The rate at which stored energy can be delivered per unit mass (W kg⁻¹) or area (W m⁻²).

Solid electrolyte: A non-liquid ion-conducting medium that provides mechanical integrity and ionic transport between electrodes.

Buckypaper: A freestanding film of entangled carbon nanotubes with high conductivity and large surface area, often used as a precursor electrode layer.

References

1. Robust Single‐Walled Carbon Nanotube‐Infiltrated Carbon Fiber Electrodes for Structural Supercapacitors: from Reductive Dissolution to High Performance Devices. Advanced Functional Materials (2023).
2. High-strength and machinable load-bearing integrated electrochemical capacitors based on polymeric solid electrolyte. Nature Communications (2023).
3. Energy storage in structural composites by introducing CNT fiber/polymer electrolyte interleaves. Scientific Reports (2018).
4. Scalable electrochemical grafting of anthraquinone for fabrication of multifunctional carbon fibers. Journal of Material Science and Technology (2024).
5. A critical review of structural supercapacitors and outlook on future research challenges. Composites Science and Technology (2023).