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.