Tailoring the supercapacitive performances of noble metal oxides, porous carbons and their composites

Porous electrochemical supercapacitive materials, as an important type of new-generation energy storage devices, require detailed analysis and knowledge of their capacitive performances under different charging/discharging regimes. An investigation of the responses to dynamic perturbations of typical representatives, noble metal oxides, carbonaceous materials and RuO2-impregnated carbon blacks, by electrochemical impedance spectroscopy (EIS) is presented. This presentation follows a brief description of supercapacitive behavior and origin of pseudo-capacitive response of noble metal oxides. For all the investigated materials, the electrical charging/discharging equivalent of the EIS response was found to obey the transmission line model envisaged as a so-called resistor/capacitor (RC) ladder. The ladder features are correlated to material physicochemical properties, its composition and the composition of the electrolyte. Fitting of the EIS data of different supercapacitive materials to appropriate RC ladders enables in-depth profiling of the capacitance and pore resistance of their porous thin-layers and finally the complete revelation of capacitive energy storage issues.