Hydrothermally synthesized aster flowers of MnCo2O4 for development of high-performance asymmetric coin cell supercapacitor

Abstract

In this study, manganese cobaltite (MnCo2O4) grown on Ni-foam are deposited by hydrothermal method at dif-ferent deposition times (2, 4, 6, and 8 h). The MnCo2O4 electrodes were systematically characterized in terms of their structural, morphological, and electrochemical properties. The cubic crystal system of MnCo2O4 with Fd3m space group is revealed by X-ray diffraction. A morphological evolution from nanograins towards aster -flower-like nanostructures can be seen in the field emission scanning electron microscopy images. The stoi-chiometry of Mn, Co, and O elements and their valance states are studied using Energy Dispersive Spectroscopy. and X-ray Photoelectron Spectroscopy respectively. An aster -flower-like nanostructure of MnCo2O4 (8 h), exhibits areal capacitance of 11.4 Fcm-2, and an energy density of about 0.98 mWhcm-2 was evaluated at 3 mAcm-2 current density within the -0.3 to 0.5 V potential window. An asymmetric coin cell (ASCC) device demonstrated an areal capacitance of 47.4 mFcm-2, energy density of 13.0 mu Whcm-2, and power density of about 0.525 mWcm-2 was measured at 0.5 mAcm-2 applied current with exceptional cycla-bility of 95 % measured up to 9000 cycles.