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

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.

Automated summary

In this study, MnCo2O4 was grown on Ni-foam by hydrothermal method with different deposition times. The structural, morphological, and electrochemical properties of the MnCo2O4 electrodes were systematically characterized. XRD analysis revealed the cubic crystal system of MnCo2O4 with the Fd3m space group. FESEM images displayed a morphological evolution from nanograins to aster-flower-like nanostructures. The stoichiometry of Mn, Co, and O elements as well as their valence states were investigated by EDS and XPS, respectively. The aster-flower-like MnCo2O4 nanostructure (8 h) exhibited an areal capacitance of 11.4 Fcm-2 and an energy density of about 0.98 mWhcm-2 at a current density of 3 mAcm-2 within the -0.3 to 0.5 V potential window. An asymmetric coin cell (ASCC) device showed an areal capacitance of 47.4 mFcm-2, energy density of 13.0 μWhcm-2, and power density of about 0.525 mWcm-2 with exceptional cyclability of 95% measured up to 9000 cycles.