Preparation and electrochemical performance of nanostructured Co₃O₄ particles

The nanostructured Co₃O₄ particles were prepared by a simple and inexpensive precipitation method, which can be used as electrode materials in pseudocapacitive energy storage devices. The effect of temperature on the crystal structure and morphology of the material was discussed to obtain a suitable condition for the fabrication of the electrodes. The results showed that the Co₃O₄ calcined at 400 °C (C4) with an average particle size of 34.1 ± 4.0 nm is suitable for electrode fabrication. This is due to the superior electrical conductivity and high purity of the phase structure with a larger specific surface area and porosity compared to the samples calcined at 600 and 800 °C. Moreover, the different oxidation states of Co ions in electrochemical reactions are the main factor for the high capacitance values of the sample. The maximum specific capacitance of 115.3 F/g at a current density of 1 A/g was achieved by the C4 sample. The charge/discharge stability measurements with maximum a of 5000 cycles showed that the sample can achieve excellent retention of specific capacitance of almost 100% for up to 1900 cycles at a current density of 5 A/g.