Electrospun MgCo2O4 nanofibers as an efficient electrode material for pseudocapacitor applications: Effect of calcination temperature on electrochemical performance

Magnesium cobaltite (MgCo2O4) nanofibers have been prepared by a sol-gel electrospinning method. The effect of calcination temperature (500, 600, and 700 degrees C) on the physical properties of the product have been investigated by various techniques, such as TG/DTA, XRD, BET, FTIR, FESEM, EDS, and DRS. The XRD patterns indicated the co-existence of two phases of MgCo2O4 and MgO, and calcination at higher temperatures favored the MgCo2O4 spinel phase of the nanofibers. Optical studies have revealed that the band gap narrowed from 3.88 to 3.80 eV with increasing calcination temperature. The specific surface areas of the samples evaluated by the BET method concomitantly decreased from 34.65 to 6.48 m(2) g(-1) as the calcination temperature was increased from 500 to 700 degrees C. FESEM images revealed that calcination at higher temperatures interrupted the fiber structure and decreased the aspect ratio, ultimately leading to a rod-like morphology at 700 degrees C. The electrochemical performances of the MgCo2O4 electrodes have been assessed by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). According to the CV results, the maximum specific capacitance observed for the electrode material calcined at 500 degrees C was 324 F g(-1) at a scan rate of 5 mV s(-1), making it promising for application in pseudocapacitors. Moreover, the GCD results demonstrated that the sample calcined at 500 degrees C delivered a specific capacitance of 210 F g(-1) at 0.5 A g(-1) and that the capacitance retention was 87.80% after 3000 charge-discharge cycles at a current density of 3 A g(-1), suggesting high cycling stability.

Automated summary

Magnesium cobaltite (MgCo2O4) nanofibers were prepared by a sol-gel electrospinning method and the effects of different calcination temperatures on their physical properties were investigated using various techniques. Higher calcination temperatures favored the MgCo2O4 spinel phase, but caused interruption of the fiber structure and a change in morphology. Samples calcined at 500 degrees C exhibited higher specific capacitance and cycling stability, showing potential for applications in pseudocapacitors.