Hausmannite Manganese oxide cathodes for supercapacitors: Surface Wettability and Electrochemical Properties

Mn3O4 thick film electrodes have been synthesized by spray pyrolysis method. Effect of its two important synthesis parameters viz. solution feed rate and substrate temperature has been studied. Solution feed rate was studied in the range of 150 to 250 cc.min(-1) while substrate temperature was varied from 325 to 400 degrees C. X-ray diffraction studies confirms Hausmannite crystal structure and SEM studies show spherical grains, uniformly distributed porous microstructure obtained for deposited Mn3O4 thick films. The contact angle measurements show these electrodes have very low contact angle in the range of 2-8 degrees and high surface energy. Cyclic voltammetry study showed specific and interfacial capacitance of Mn3O4 electrodes increased with increase in solution feed rate, due to increased thickness of films. On the other hand, substrate temperature shows effect on film morphology, grain size and porosity, however, does not show any explicit effect on specific and interfacial capacitance. Highest values of specific and interfacial capacitance exhibited by Mn3O4 are 187.79 F.g(-1) and 0.82 F.cm(-2) respectively for sample prepared at 250 cc.min(-1) solution feed rate and 325 degrees C substrate temperature. The calculated energy density and power density for the same sample was 26.08 Wh.kg(-1) and 1.01 kW.kg(-1) respectively. (C) 2017 Elsevier Ltd. All rights reserved.