Enhancing electrochemical capacitor performance through the application of nanostructured carbon materials as conducting additives

This paper demonstrates the high suitability of nanostructured carbon materials as percolators in activated carbon-based electrode materials for symmetric capacitors working in neutral electrolytes. Four different carbon nanomaterials, pristine carbon nanofibers (CNFs), CNF-based nanomaterials as oxidized CNFs and activated CNFs, and reduced graphene oxide (rGO), were used as conductive additives and compared with commercially used carbon black (CB). Pristine CNFs were used to evaluate the optimal content of nanostructured carbon material in the activated carbon-based electrode. The addition of 3 wt.% CNFs was sufficient to achieve better capacitor performance than the addition of 5 wt.% CB. Furthermore, the superior electrochemical performance of the device was revealed when 3 wt.% rGO was introduced as a percolator, maintaining not only a high capacitance value at low scan rates and current densities but also an improved rate capability at high current regimes. The two-dimensional structure of rGO, its developed porosity and good dispersion within the electrode material results in a superior device with the lowest relaxation time constant of 5 s, which is over twelve times lower than the capacitor with commercial CB as the percolator.