Hydrothermal synthesis of nickel foam-supported spinel ZnNi2O4 nanostructure as electrode materials for supercapacitors

Here, we demonstrate how moderate changes in the hydrothermal reaction parameters lead to the formation of spinel-type Zinc/nickel-based electrode materials on the nickel foam (ZnNi2O4/NF) possessing highly porous structures and well-organized active sites. The ZnO+NiO/NF sample is prepared as the reference electrode material, and its physicochemical and electrochemical characteristics are compared with those of ZnNi2O4/NF. ZnO+NiO/NF provides a hierarchical porous structure with an average pore diameter of 2 μm, a high specific capacity of 235 C g−1 at the current density of 1 A g−1, and an energy density of 19.4 Wh Kg−1 in the corresponding power density of 300 W Kg−1. However, ZnNi2O4/NF exhibits a considerably higher energy density of 386 C g−1 at the current density of 1 A g−1 while showing a comparable power density to ZnO+NiO/NF. ZnNi2O4/NF retains 83% its initial capacity after experiencing 1500 cycles at the current density of 10 A g−1. ZnNi2O4/NF shows a high energy density of 32.15 Wh Kg−1 in the corresponding power density of 317 W Kg−1, which surpasses the performance of the previously-reported electrode materials prepared based on Zn and Ni for application in supercapacitors.