Multifunctional Carbon Fiber Composites: A Structural, Energy Harvesting, Strain-Sensing Material

Multifunctional structural materials are capable of reducing system level mass and increasing efficiency in load -carrying structures. Materials that are capable of harvesting energy from the surrounding environment are advantageous for autono-mous electrically powered systems. However, most energy harvesting materials are non-structural and add parasitic mass, reducing structural efficiency. Here, we show a structural energy harvesting composite material consisting of two carbon fiber (CF) layers embedded in a structural battery electrolyte (SBE) with a longitudinal modulus of 100 GPa-almost on par with commercial CF pre-pregs. Energy is harvested through mechanical deforma-tions using the piezo-electrochemical transducer (PECT) effect in lithiated CFs. The PECT effect creates a voltage difference between the two CF layers, driving a current when deformed. A specific power output of 18 nW/g is achieved. The PECT effect in the lithiated CFs is observed in tension and compression and can be used for strain sensing, enabling structural health monitoring with low added mass. The same material has previously been shown capable of shape morphing. The two additional functionalities presented here result in a material capable of four functions, further demonstrating the diverse possibilities for CF/SBE composites in multifunctional applications in the future.

Automated summary

Multifunctional structural materials have the potential to reduce system mass and improve efficiency, and materials that can harvest energy from the surrounding environment are advantageous for autonomous electrically powered systems. This study presents a structural energy harvesting composite material comprised of carbon fiber layers embedded in a structural battery electrolyte. The material demonstrates the piezo-electrochemical transducer effect, which allows for energy harvesting through mechanical deformations. The same material also has shape morphing capabilities and strain sensing for structural health monitoring.