Practical mechanochemical synthesis and electrochemical properties of Mn3O4 for use in supercapacitors

A facile method to synthesize Mn3O4 crystalline powders for use in supercapacitor electrodes is reported. Specifically, the mechanochemical synthesis was carried out with high-energy ball milling and a short milling time of 1 h. The physicochemical properties of the resultant powders were characterized by XRD, Raman spectroscopy, SEM, and N2 adsorption-desorption techniques. In addition, the electrochemical capabilities were tested in two different configurations: a three-electrode cell, and a symmetric supercapacitor (SSC) with a two-electrode arrangement. Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge were applied to the samples with both configurations. The Mn3O4 samples were synthesized from manganese chloride tetrahydrate and sodium peroxide with two molar ratios, 1:1 and 1:1.5. The samples showed excellent electrochemical stabilities of 99.7 % after 5000 charge-discharge cycles, and the highest electrochemical capacitance of 485 F·g1 at 5 mV s1 was observed for the sample prepared with a 1:1 ratio of reagents and used with the three-electrode configuration.