Effect of annealing temperature on supercapacitive performance of SILAR-grown Mn3O4 nanoflakes

Abstract

The effect of annealing temperature on Mn3O4 thin films for their electrochemical energy-storing performance was studied. The Mn3O4 thin films were synthesized by the successive ionic layer absorption and reaction (SILAR) method. The annealing temperature was varied from 50 to 350 °C and their subsequent impact on structural, morphological, and electrochemical properties were analyzed. X-ray diffraction studies confirmed that the Mn3O4 thin films had a tetragonal hausmannite structure, which was further confirmed by X-ray photoelectron spectroscopy, wherein a spin-orbit splitting energy of 11.69 eV was observed in the Mn 2p3/2 and Mn 2p1/2 doublet states. The effect of annealing on morphological modifications was investigated using SEM analysis. The as-deposited amorphous Mn3O4 thin films having granular nanoclusters were further modified into nanoflakes by increasing the annealing temperature. Charge storage kinetics were studied using cyclic voltammetry and electrochemical impedance spectroscopy. The Mn3O4 thin films annealed at 250 °C have the highest specific capacitance of 87.84 mF/cm2 at 2.5 mA/cm2 with 97.62 % of coulombic efficiency. Moreover, the electrochemical stability of 82 % after 2000 CV cycles confirmed the potential candidature for the design and development of potential energy-storing Mn3O4 electrodes for future wearable and electronic device applications.