Effect of calcination temperature on the morphology and electrochemical properties of Co3O4 for lithium-ion battery

A simple approach to synthesize Co₃O₄ in mass production by using hexamethylenetetramine (HMT, C₆H₁₂N₄) as a precipitator via hydrothermal treatment has been developed. The samples were calcinated at different temperatures ranging from 300 to 600 °C and characterized by XRD and SEM. The structure became agglomerative and collapsed with an increase in calcination temperature. Evaluation of the electrochemical performance in combination with SEM and BET analysis suggests that there is an optimum calcination temperature for Co₃O₄. It is found that the retention capacity of well crystallized Co₃O₄ hollow microspheres has a higher specific surface area at 300 °C and is almost above 94% after the 5th cycle at different current densities of 40 and 60 mA g⁻¹, which shows good long-life stability and favorable electrochemical behaviors. Using EIS analysis, we demonstrated that lithium-ion conduction inside the SEI layers and charge transfer at the electrode/electrolyte interface became hindered with an increased calcination temperature, which was in good agreement with the electrochemical behaviors of three Co₃O₄ electrodes. It is proposed that drastic capacity fading and the variation of resistive components (SEI layers and charge transfer) can be influenced by morphologies due to the calcination temperature.