Meso-macroporous Co3O4 electrode prepared by polystyrene spheres and carbowax templates for supercapacitors

Meso-macroporous Co3O4 electrode is synthesized by drop coating with a mixed solution containing Co(OH)2 colloid, polystyrene spheres, and carbowax (namely polyethylene glycol), followed by calcining at 400 °C to remove polystyrene spheres and carbowax. For comparison, nonporous Co3O4 and mesoporous Co3O4 electrodes are prepared by drop coating with Co(OH)2 colloid and with a mixed solution containing Co(OH)2 colloid and carbowax under the same condition, respectively. Capacitive property of these electrodes is measured by cyclic voltammetry, potentiometry and electrochemical impedance spectroscopy. The results show that meso-macroporous Co3O4 electrode exhibits larger specific capacitance than those of nonporous Co3O4 electrode and mesoporous Co3O4 electrode at various current densities. The specific capacitance of meso-macroporous Co3O4 electrode at the current density of 0.2 A g−1 is 453 F g−1. Meanwhile, meso-macroporous Co3O4 electrode possesses the highest specific capacitance retention ratio at the current density ranging from 0.2 to 1.0 A g−1, indicating that meso-macroporous Co3O4 electrode suits to high-rate charge–discharge.