Microstructure and Electrochemical Performance of Co₃O₄ Nanopillars Calcinated at Various Temperatures

One-dimensional (1D) Co3O4 nanopillars were prepared by a facile hydrothermal-calcination method, which involved low thermal decomposition of Co(OH)y(CO3)0.5(2-y) · 11H2O at different temperatures. Microstructure, lithium-storage performance and the conductivity of the Co3O4 nanopillars calcined at different temperatures were systematically investigated. It was revealed that the calcined temperature has an effect on the particle size, crystallinity, and morphology of the Co3O4 nanopillars, which further influenced its electrochemical performance. It was found that when the calcined temperature and time were 450 °C and 2 h, respectively, the obtained Co3O4 nanopillars with the length of 60-100 nm and width of 30-40 nm, presented good lithium-storage performance with a high reversible capacity of 805.8 mAh g-1 after 30 cycles at a current density of 100 mA g-1. In addition, the Co3O4 nanopillars electrode possessed the smallest semicircle diameter, which implied that Co3O4 nanopillars presented the lowest contact and charge-transfer impedances, originating from its good crystallinity and 1D nanocolumnar structure.