Introduction of Co 3 O 4 to MnO 2 /activated carbon for high performance electrode materials toward electrochemical capacitor application

Cobalt oxide has been chosen for incorporating with MnO 2 /activated carbon (AC) material. The samples were characterized by means of X‐ray diffraction (XRD), transmission electron microscopy (TEM), and isothermal adsorption – desorption of N 2 at 77.35 K (BET). The results showed that the CoMn/AC samples are amorphous and covered by homogeneous, dispersed oxide particles. The BET surface area and pore volume are up to 2826 m 2 /g and 1.7441 cm 3 /g, respectively. The electrochemical characterization was performed using cyclic voltammetry and galvanostatic charge/discharge test in 6.0 M KOH electrolyte. CoMn/AC electrode incorporated with 1.5 % Co 3 O 4 exhibited higher specific capacitance than other percentages, reached 358 F/g at a scan rate of 5 mV/s and 1159 F/g at specific current density of 0.5 A/g. The enhanced capacitance is attributed to the combination of two charge storage mechanism: electrical double layer capacitor and pseudo‐capacitor.