A zinc-cobalt–nickel heterostructure synthesized by ultrasonic pulse electrodeposition as a cathode for high performance supercapacitors

Abstract

• Zinc-cobalt–nickel heterostructure electrode prepared by ultrasonic pulse electrodeposition. • The ZCN electrode exhibited a high specific capacitance of 1774F g −1 at a current density of 1 A g −1 . • The asymmetric supercapacitor consisted of ZCN cathode and active carbon anode have high energy and power densities. A zinc-cobalt–nickel (ZCN) heterostructure was directly synthesized on nickel foam using a smart ultrasonic pulse electrodeposition method. The electrochemical results showed that the ZCN heterostructure, in which Zn-doped Co(OH) 2 served as the inner layer and Zn-doped Ni(OH) 2 served as the outer layer, exhibited a high specific capacitance of 1774F g −1 at a current density of 1 A g −1 . It also showed excellent rate capability (91% of capacity retention at 10 A g −1 ) and good cycling stability (75.21% capacity retention after 1,000 cycles at a high current density of 20 A g −1 ). Moreover, an asymmetric supercapacitor was designed based on a ZCN cathode and an active carbon anode. The supercapacitor possessed high energy densities (39.6 Wh kg −1 at 400 W kg −1 and 20.3 Wh kg −1 at 6347 W kg −1 ) and extraordinary cycling stability (85.5% of initial capacity after 1000 cycles at a high current density of 6 A g −1 ). This ZCN heterostructure therefore has potential applications as a cathode material for supercapacitors.