Study of the Design and Performance of Multibody Carbon Fiber Structural Supercapacitors with Superior Mechanical and Electrochemical Properties

In response to the fast-growing global demand for electric aircraft, carbon fiber (CF) structural energy storage technology is being adopted to significantly enhance the energy storage efficiency while reducing flight weight. To achieve the design goals of large capacitance and high power, this study used a longitudinal stacking method to design a multibody carbon fiber structural supercapacitor (multibody CFSSC). Results showed that the AC&GO structural electrode exhibited a high specific surface area of 95.31 m²/g and a specific capacitance of 225 mF/cm². Compared to the monolithic CFSSC (1-SC), the multibody CFSSC (4-SC) had a power density of 7.24 W/m² in series and a specific capacitance of 78.72 mF/cm² in parallel, with respective increases of 302.2% and 275.72%. The capacitance retention and Coulombic efficiency of the multibody CFSSCs were maintained at approximately 99% and 96% after 10,000 cycles. Meanwhile, under load-bearing and tensile load, the capacitance retention of the multibody CFSSC was maintained at 98% and 95%, respectively. These results indicated that it has superior long-cycle stability. The tensile strength and elastic modulus of the multibody CFSSCs were 683.66 MPa and 15.92 GPa, respectively, increasing by 388.82% and 82.99%, compared to those of the monolithic CFSSC. Moreover, the mechanical property retention could reach 92.5% compared with the nonenergy-storing CF structural parts. Finally, the multifunctional efficiency evaluation demonstrated that the design of multibody CFSSCs effectively enhanced mechanical-electrochemical performance, offering a valuable concept and reference for the practical applications of wide voltage and high current energy storage in aerospace.