Abstract
Metal oxide nanosheets and nanoflakes are potentially active materials for the fabrication of supercapacitors electrode development owing to their large three dimensional (3D) surface area and high electrochemical ac-tivity. In this work, hierarchical three dimensional nanoflakes (H3DN) of nickel oxide (NiO) were designed and successfully grown on carbon microfibers (CMF) as a binder free electrode material i.e. H3DN-NiO@CMF for supercapacitor applications via a facile and simple hydrothermal method. The reaction parameters were suc-cessfully optimized to obtain efficient growth, porous structure, and uniform morphology. The resulting opti-mized electrodes were characterized using various microscopic and spectroscopic techniques and further electrochemical supercapacitive performance were analyzed in half and full cell assemblies. The porous structure of the carbon microfiber could be effectively inherited and used as a binder free electrode, the three-electrode system exhibited satisfactory electrochemical performance with a high areal capacitance of 2322.6 mF/cm(2) and an excellent cyclic stability with retention up to 87.40 %. In two-electrode symmetric supercapacitor system comprising H3DN-NiO@CMF electrodes exhibited an excellent cyclic stability up to 79.1 % after 7000 cycles and the highest energy density of 154.1 mWh kg(-1) at a power density of 2801.8 mWkg(-1). The outstanding per-formance could be attributed to the 3D porous structure, nanoflake morphology, and good conductivity of the H3DN-NiO@CMF electrodes, which could ensure a rapid transport of the ions and electrons. The obtained results demonstrate that H3DN-NiO@CMF electrodes are potential candidates for energy storage applications.