Surface Modifications of Carbon Fiber Electrodes for Structural Supercapacitors

Structural electrodes for supercapacitors based on woven carbon fiber were made from different surface modification approaches, such as spray coating with carbon nanoparticles (graphene nanoplatelets and multiwall carbon nanotubes, GNP and MWCNT, respectively) and direct synthesis of carbon aerogel (CAG) on the surface of the carbon fabric. Suitability of the different modification techniques was stablished based on the results from cyclic voltammetry and single fiber tensile test. Highest capacitance was achieved by the synthesis of CAG although mechanical properties were negatively affected. These treatments produced a good combination of mechanical and electrochemical properties, which suggests these electrodes are suitable for multifunctional applications. In particular, capacitance was improved by increasing the surface area of commercial carbon fiber fabric while keeping its mechanical properties. The best combination of properties was achieved by deposition of GNP by spray coating. Mechanical properties kept unaffected and capacitance was increased by an order of magnitude compared with the pristine carbon fiber.