High-Performance Multifunctional Structural Supercapacitors Based on In Situ and Ex Situ Activated-Carbon-Coated Carbon Fiber Electrodes

With the rapid consumption of fossil fuels and the massive emission of pollutants, multifunctional materials are the upgrading trend of automotive and aerospace structures. As a promising structural energy storage device, the specific capacitance of a carbon-fiber-based structural supercapacitor is greatly limited as a result of the low specific surface area of carbon fiber electrodes. In this work, we prepared high-performance structural supercapacitors that consisted of in situ and ex situ activated carbon (AC)-coated carbon fiber electrodes, glass fiber separator, and bicontinuous structural electrolyte. The specific capacitances of the structural supercapacitors increased from 8.67 × 10^-3 to 13.12 F/g after the coating of AC, while the tensile properties were basically maintained, which were much higher than the results of the state-of-art performance for structural supercapacitors. The tensile strength and modulus were 257.78 MPa and 23.20 GPa, respectively, as the mass fraction of AC increased to 15%. A total of 95% of the capacitance could be maintained in structural supercapacitor devices with a larger size of 15 × 15 cm, showing promising engineering prospects of AC-coated structural supercapacitors. The method in this work provided a facile route for realizing the large-scale production and engineering application of high-performance structural supercapacitors.