Rapid microwave-assisted solid-state obtention of Mn3O4 and its electrochemical characterization for application as supercapacitor electrodes

• Published in: Ionics Vol. 28; no. 8; pp. 3963 - 3974
• Main Authors: Silva, João Pedro, Irikura, Kallyni, Biaggio, Sonia R., Bocchi, Nerilso, Rocha-Filho, Romeu C.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2022; Springer Nature B.V
• Subjects: Aqueous solutions; Ball milling; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Differential thermal analysis; Electrochemical analysis; Electrochemistry; Electrodes; Energy Storage; Manganese dioxide; Manganese oxides; Microwaves; Optical and Electronic Materials; Original Paper; Photomicrographs; Raman spectroscopy; Renewable and Green Energy; Supercapacitors; Thermal decomposition; Supercapacitor cathode material; Energy storage materials; Microwave solid-state synthesis; Pseudocapacitance; Precursor ε-MnO; Solid-state reactions
• ISSN: 0947-7047; 1862-0760
• DOI: 10.1007/s11581-022-04627-y

A rapid and facile microwave-assisted method coupled with a mild mechanical treatment is proposed to obtain Mn 3 O 4 with good properties to be used as a supercapacitor material. Mn 3 O 4 was produced by thermal decomposition of ε-MnO 2 using microwave irradiation in a practical setup and a domestic microwave oven. XRD results, supported by other physical characterizations such as TG/DTA and FTIR and Raman spectroscopy analyses, attested that Mn 3 O 4 was obtained as a single phase after only 5 min of microwave heating. After submitting an oxide sample to a mild mechanical treatment in an adapted ball-mill setup for 30 min, SEM micrographs and BET analyses revealed a particle size in the range of 200–600 nm and a fivefold increase of the specific surface area. The pseudocapacitive behavior of electrodes prepared with the thus obtained Mn 3 O 4 was analyzed by cyclic voltammetry in a 0.1 mol L –1 Na 2 SO 4 aqueous solution. Galvanostatic charge and discharge tests of these electrodes were performed in the 1.0 to 5.0 A g –1 range in the same electrolyte; at 1.0 A g –1 , they presented an initial specific capacitance of about 160 F g –1 and good electrochemical stability up to 5000 cycles.