High-performance asymmetric supercapacitor based on a CdCO 3 /CdO/Co 3 O 4 composite supported on Ni foam - part II: a three-electrode electrochemical study.

A binder-free CdCO 3 /CdO/Co 3 O 4 compound with a micro-cube-like morphology on a nickel foam (NF) made via a facile two-step hydrothermal + annealing procedure has been developed. The morphological, structural and electrochemical behavior of both the single compounds constituting this final product and the final product itself has been studied. The synergistic contribution effect of the single compounds in the final compounded resulting specific capacitance values are presented and discussed. The CdCO 3 /CdO/Co 3 O 4 @NF electrode exhibits excellent supercapacitive performance with a high specific capacitance ( C S ) of 1.759 × 10 3 F g -1 at a current density of 1 mA cm -2 and a C S value of 792.3 F g -1 at a current density of 50 mA cm -2 with a very good rate capability. The CdCO 3 /CdO/Co 3 O 4 @NF electrode also demonstrates a high coulombic efficiency of 96% at a current density as high as 50 mA cm -2 and also exhibits a good cycle stability with capacitance retention of ca. 100% after 1000 cycles at a current density of 10 mA cm -2 along with a potential window of 0.4 V. The obtained results suggest that the facilely synthesized CdCO 3 /CdO/Co 3 O 4 compound has great potential in high-performance electrochemical supercapacitor devices.