Effect of gradient controlled pyrolysis process on electrochemical performance of cobalt oxide nanobelts

Abstract

The morphological changes of electrode materials influence their electrochemical performance. In this work, we synthesize cobalt oxide nanomaterial by a facile electrospinning-annealing process. During the pyrolysis step, the annealing temperature and holding time are used to control the morphology and properties of samples. Results demonstrate that the main component of cobalt oxide is Co3O4 and the morphology of Co3O4 changes from nanofibers to nanobelts (NB) with annealing temperature and time. The cyclic voltammogram (CV) curves are analyzed to compare the electrochemical performances of the electrodes. It reveals that the temperature has a greater impact on the specific capacitance of the electrode than the time. Among them, Co3O4-350-5 electrode presents the best capacitive properties in three-electrode system, which displays a high specific capacitance (335.5 F g−1 at 0.5 A g−1) and excellent rate capability (58% capacitance retains at a high current density of 30 A g−1). The asymmetric device assembled by Co3O4-350-5 displays a long cycling life (87.6% capacitance remains after 3000 cycles) and a high power density (26.5 kW kg−1).