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

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.