Cobalt oxide microtubes with balsam pear-shaped outer surfaces as anode material for lithium ion batteries

Co3O4 microtubes with balsam pear-shaped outer surfaces and void spaces were synthesized by the Kirkendall effect. Intermediate phase Li1.47Co3O4 was detected by X-ray diffraction (XRD) to illustrate the severe volume change during electrode reactions and detail the conversion of Co3O4 to Li2O and Co. Changes in and influences on Li2O and Co during the first cycle were explored through calculations based on electrochemical impedance spectroscopy (EIS) tests to obtain a better understanding of the electrode reaction processes. The void spaces in the tube walls accommodated the volume change during electrode reactions, and the balsam pear-shaped outer surfaces expanded the available active surface for electrode reactions. As a result, the prepared Co3O4 microtubes exhibited strong electrochemical performance. The first discharge capacity reached similar to 907 mAh g(-1) at 5.00 mA cm(-2), and discharge capacity remained above 400 mAh g(-1) until the 40th cycle at 0.05 mA cm(-2).