Facile one pot sonochemical synthesis of CoFe2O4/MWCNTs hybrids with well-dispersed MWCNTs for asymmetric hybrid supercapacitor applications

In this study, a facile sonochemical strategy is used for the fabrication of CoFe2O4/MWCNTs hybrids as an electrode material for supercapacitor applications. FE-SEM image demonstrates the uniformly well-distributed MWCNTs as well as porous structures in the prepared CoFe2O4/MWCNTs hybrids, suggesting 3D network formation of conductive pathway, which can enhance the charge and mass transport properties between the electrodes and electrolytes during the faradic redox reactions. The as-fabricated CoFe2O4/MWCNTs hybrids with the MWCNTs concentration of 15 mg (CFC15) delivers maximum specific capacitance of 390 F g−1 at a current density of 1 mA cm−2, excellent rate capability (275 F g−1 at 10 mA cm−2), and outstanding cycling stability (86.9% capacitance retention after 2000 cycles at 3 mA cm−2). Furthermore, the electrochemical performance of the CFC15 is superior to those of pure CoFe2O4 and other CoFe2O4/MWCNTs hybrids (CFC5, CFC10 and CFC20), indicating well-dispersion MWCNTs and uniform porous structures. Also, as-fabricated asymmetric supercapacitor device using the CoFe2O4/MWCNTs hybrids as the positive electrode and activated carbon as the negative electrode materials shows the outstanding supercapacitive performance (high specific capacitance, superior cycling stability and good rate capability) for energy storage devices. It delivers a capacitance value of 81 F g−1 at 3 mA cm−2, ca. 92% retention of its initial capacitance value after 2000 charge-discharge cycles and excellent energy density (26.67 W h kg−1) at high power density (~319 W kg−1).