Hydrothermal synthesis of Co3O4 with different morphologies and the improvement of lithium storage properties

A simple hydrothermal treatment was developed to synthesize Co3O4 powders with different morphologies in mass production by using hexamethylenetetramine (HMT, C6H12N4) as a precipitator. By changing the initial HMT concentrations, the prepared Co3O4 powders were readily regulated in its morphologies, which varied from microsphere to urchin-like hollow microsphere, and finally to collapsed porous structure. Moreover, the four Co3O4 powders with different HMT concentrations had been applied in the negative electrode materials for lithium ion batteries, which exhibited different electrochemical properties. The present research demonstrated that morphology was one of the crucial factors that affected the electrochemical properties of electrodes. The capacity retention of sample with an original Co(NO3)2:HMT mole ratio of 1:1 is almost above 94% from the 5th cycle at different current densities of 40 and 60 mA g−1, exhibiting the better long-life stability and favorable electrochemical behaviors due to its higher specific surface area (97.1 m2 g−1) and the uniform urchin-like hollow structure.

► Hydrothermal treatment to obtain four Co3O4 hollow microspheres.
► Hexamethylenetetramine (HMT) as a precipitator.
► Investigate the effects of the initial HMT concentrations on the morphology and electrochemical properties.
► Urchin-like hollow microsphere has the higher specific surface area and uniform structure.
► Urchin-like hollow microsphere electrode possessed large initial reversible capacity and better capacity retention.