Design and construction of hierarchical α-Co(OH)2-coated ultra-thin ZnO flower nanostructures on nickel foam for high performance supercapacitors

Abstract

Abstract Most pseudocapacitor materials have only near-surface parts participated into the Faradic-reaction, and their low contribution limits the development of pseudocapacitors. In this situation, hierarchical α-Co(OH)2-coated ultra-thin ZnO flower nanostructures on nickel foam (NF@ZnO@Co(OH)2) are designed and constructed to enhance the efficiency of charge and ion-transfer process as well as to improve the low contribution of pseudoactive materials during the Faradic-reaction. The ultra-thin petal ZnO flower-like nanostructures can take the role of the effective backbones for succeeding synthesis of electrochemical active materials. The optimized electrodes exhibited an outstanding pseudocapacitive performance, including an excellent durability, wide working potential window (0.55 V in galvanostatic charge-discharge measurement) and a high specific capacitance of 2396.4 F g−1. Additionally, we have constructed an asymmetric supercapacitor device and it delivers a prominent energy density of 62.57 Wh kg−1 at a power density of 711.28 W kg−1 with a cell voltage of 1.5 V and an excellent durability. Thereby, the NF@ZnO@Co(OH)2 is one promising supercapacitors electrode material for practical application.