Zn2+ doped Ni3(NO3)2(OH)4 nanoflower spheres for electrochemical applications

Abstract

In this present work, Ni3(NO3)2(OH)4 doped with Zn2+ ions are prepared by a solvothermal method using Ni(NO3)2·6H2O, Zn(NO3)2·6H2O, C16H33(CH3)3NBr (CTAB) and C2H5OH as raw materials. Characterization methods such as X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) are used to analyze the materials. Cyclic voltammetry (CV) and galvanostatic charge–discharge curves (GCD) are employed to compare the electrochemical performance of materials with different doping amounts. The electrochemical test results show that doping with Zn2+ significantly enhances the poor electrical conductivity of Ni3(NO3)2(OH)4. Electrochemical tests reveal that the doping amount of 0.4 mmol has the best electrochemical performance with a mass-specific capacitance of 1832 F·g−1 at a current density of 1 A·g−1 in the three-electrode system which is much higher than that of undoping sample (771 F·g−1). Additionally, the assembled NiZn-0.4//AC asymmetric supercapacitor device (ASC) has an energy density of 61.9 Wh·kg−1 at a power density of 747.8 W·kg−1. The Coulombic efficiency retention of the ASC device remains at 98 % after 2000 galvanostatic charge–discharge circles, and the specific capacitance retention is 91 % of the initial value. The doping of Zn2+ provides a valuable approach for enhancing the conductivity and specific capacitance of nickel-based supercapacitor electrode materials.