Influence of the heat treatment on the MOF-derived Co3O4 coatings on carbon fiber fabrics used for structural supercapacitor applications

Abstract

Currently, electric vehicles have emerged as a cleaner alternative to their fossil-fuel counterparts. However, their features, especially their autonomy, are still far from what is expected. In this way, the development of structural supercapacitors based on multifunctional composite materials is being studied as a promising approach for reducing the weight of electric vehicles, which is essential to improve their energetic efficiency. Carbon fibers could serve the dual function of electrodes and reinforcements due to their high electrical conductivity and excellent specific mechanical properties. In this study, Co3O4 has been synthesized directly over a structural carbon fiber fabric using the ZIF-L metal-organic framework (MOF) as a precursor. Moreover, the influence of the temperature and time in the annealing and oxidation stages on the performance of fibers as an electrode for structural supercapacitors have been studied. The optimized coating exhibited a specific capacitance of 456.5 F/g of active material at a current density of 50 mA/g, demonstrating the significant impact of heat treatment on the MOF-derived Co3O4 coating. Moreover, a symmetric structural supercapacitor was fabricated, displaying a specific capacitance of 13.71 mF/g and an elastic modulus of 35 GPa. Additionally, this supercapacitor exhibited excellent mechanical properties and promising electrochemical properties compared to the existing bibliography.