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Investigation on spinel MnCo2O4 electrode material prepared via controlled and uncontrolled synthesis route for supercapacitor application

Tholkappiyan, R., Naveen, A. Nirmalesh, Sumithra, S., Vishista, K.
Journal of materials science 2015 v.50 no.17 pp. 5833-5843
manganese, chemical composition, X-ray photoelectron spectroscopy, X-ray diffraction, micropores, electrodes, capacitance, electrochemistry, scanning electron microscopy, combustion, Fourier transform infrared spectroscopy, electrical equipment, crystallites, nanoparticles
To analyze the impact of preparation routes on the electrochemical behavior of nanoparticles, manganese cobaltite (MnCo₂O₄) has been synthesized by combustion (MnC-C) and hydrothermal route (MnC-H). The structural properties of synthesized nanoparticles were characterized by X-ray diffractometer studies which confirm the formation of cubic spinel phase with average crystallite size of 26 nm for combustion route prepared and 24 nm for hydrothermal route. The FT-IR spectrum shows two strong bands observed at 651 and 559 cm⁻¹ that are characteristic to stretching vibrations of tetrahedral and octahedral sites of spinel MnCo₂O₄ compounds. Elemental analysis, oxidation state, and chemical composition of these nanoparticles were examined using X-ray photoelectron spectroscopy. The morphology of synthesized nanoparticles was analyzed by SEM images. Loosely packed flake-like morphology was observed for MnC-H and typical spongy network structure with voids or pores was seen for MnC-C samples. BET analysis reveals the presence of mesopores and micropores in the prepared compounds. Influence of preparation route on capacitor behavior was evaluated by performing electrochemical characterizations such as cyclic voltammetry, chronopotentiometry, and AC impedance analysis. MnC-H exhibits a higher specific capacitance of 671 F g⁻¹ at 5 mV s⁻¹ scan rate compared to 510 F g⁻¹ exhibited by MnC-C electrode material. Excellent capacitance retention of 92 % was demonstrated by MnC-H over 1000 continuous cycling. Results indicate that MnCo₂O₄ prepared via controlled synthesis conditions (hydrothermal) shows better performance than combustion prepared.