Surface Functionalization of Electrodes and Synthesis of Dual-Phase Solid Electrolytes for Structural Supercapacitors

The interface between structural electrodes and solid electrolytes plays a key role in the electrical-mechanical properties of energy storage structures. Herein, we present a surface functionalization method to improve the ion conduction efficiency at the interface between a structural electrode and a solid electrolyte that consists of a bi-continuous network of epoxy and ionic liquid (IL). Composite supercapacitors made with this electrolyte and carbon fiber (CF) electrodes coated with manganese dioxide (MnO₂) demonstrate that treating the electrodes with the silane can increase the areal capacitance by 300% without degrading the tensile strength. The dual-phase electrolyte containing 40 wt % IL and 60 wt % epoxy exhibits the highest multifunctional performance, measured by the product of stiffness and ionic conductivity. The outstanding mechanical and energy storage properties demonstrate that the silane treatment of MnO₂-coated CF fabric structural electrodes is a promising method for future high-performance structural composite supercapacitors.