A comparative study on the supercapacitive behaviour of solvothermally prepared metal ferrite (MFe2O4, M = Fe, Co, Ni, Mn, Cu, Zn) nanoassemblies

Metal ferrites show excellent electrochemical properties owing to the multiple oxidation states of the metal ions which make them more suitable for electrode materials in supercapacitor applications. Here, we report the synthesis of mesoporous metal ferrites (MFe2O4, M = Fe, Co, Ni, Mn, Cu, Zn) nanoassemblies by solvothermal method in ethylene glycol solvent with the assistance of PEG 600 as co-solvent. The metal ferrites found to crystallize either in spinel or inverse spinel or mixed spinel structure with the crystallite sizes varying from 20 to 35 nm and average particle sizes ranging from 50–140 nm as determined from XRD patterns and FESEM images respectively. The supercapacitive performances were studied by cyclic voltammetry (CV), chronopotentiometry and electrochemical impedance spectroscopy (EIS) in 3 molar KOH solution as electrolyte and the performance of various ferrites were compared. The specific capacitance of metal ferrites (MFe2O4, M = Fe, Co, Ni, Mn, Cu, Zn) were calculated to be 101 F g−1, 444.78 F g−1, 109.26 F g−1, 190 F g−1, 250 F g−1, 138.95 F g−1 respectively at a scan rate of 2 mV s−1. Highest specific capacitance was found for CoFe2O4 as compared to others metal ferrites nanoassemblies (MFNs). The capacitive behaviour of CoFe2O4 was also found to vary with the morphology. [Display omitted] •Ferrite nanoassemblies (NAs) were prepared by PEG-600 assisted solvothermal method.•Reaction mechanism of formation of NAs with various distribution is explicated.•Capacitance vary on surface area, distribution, morphology and composition of NAs.•CoFe2O4 NAs exhibit superior charge storage behaviour and specific capacitance.•Internal series resistance and potential window in CV vary with composition of NAs.