The Cu-CdFe/g electrode displayed good stability with capacitance retention of 87% after 4000 cycles. The symmetric supercapacitor device (Cu-CdFe/g//Cu-CdFe/g) was fabricated and obtained the specific capacitance of 120 F g -1 at 0.25 A g -1 and the energy density of ~ 14.5 W h Kg -1 at a power density of 220 W Kg -1 . In addition, an asymmetric performance was examined using Cu-CdFe/g and AC as the positive and negative electrodes, respectively. The resultant specific capacitance of the asymmetric device was 140 F g -1 at 0.5 A g -1 , and showed