Hydrothermal synthesis of Co3O4 with different morphologies towards efficient Li-ion storage

Abstract

In this study, Co₃O₄ with different morphologies (leaf, sheet, and cube) are successfully synthesized by a facile hydrothermal method followed by calcination treatment. Representative samples with different morphological structures are compared and evaluated as anode materials in lithium-ion batteries. Relative to the Co₃O₄-sheet and Co₃O₄-cube samples, the Co₃O₄-leaf samples exhibit excellent electrochemical performance with high storage capacity (1245 mA h g⁻¹ after 40 cycles at 0.1 C) and superior rate capability (0.1, 0.2, 0.5, 1, and 2 C for 1028, 1085, 1095, 1038, and 820 mA h g⁻¹, respectively); interestingly, the thinner the samples are, the better their performance. Moreover, assisted by characterization by cyclic voltammetry and electrochemical impedance spectroscopy, we draw a conclusion that the ultra-thin structures result in shorter path lengths for the transport of lithium ions and electrons, benefiting conductivity and fast charge–discharge rates. More importantly, for Co₃O₄, the respective structure's degree of thickness has a great effect on the electrochemical performance in lithium-ion batteries. This new concept might be extended to prepare other anode and cathode materials for advanced energy storage and conversion devices.