Electrochemical investigation of Zr-doped ZnO nanostructured electrode material for high-performance supercapacitor

Simple electrochemical capacitors are promising energy storage devices because of their power capability, charge/discharge rates and life cycle. Zinc oxide is an inexpensive and eco-friendly material which can be used as a supercapacitor electrode relative to other materials with great features. With a view to enhance the electrochemical performance of ZnO (Csp of 324), the present work is focused to synthesize modified ZnO nanostructures by the dopant Zr in three different compositions (3, 6 and 9 wt% Zr-doped ZnO) via chemical coprecipitation method. The synthesized materials were characterized by physio-chemical methods. The significant capacitive behaviour of ZnO and modified ZnO and 9 wt%Zr-doped ZnO nanostructure were investigated by cyclic voltammetric (CV) studies, galvanostatic charge-discharge (GCD) analysis and electrochemical impedance spectroscopic (EIS) methods in aqueous 1 M KOH. The newly fabricated 9 wt% Zr-doped ZnO electrode exhibited excellent specific capacitance of 518 Fg−1 at a current density of 1 Ag−1. Additionally, it depicted the capacitance retention of 94% even after 5000 successive GCD cycles. Moreover, the as-prepared materials demonstrated electrochemical reversible nature.