Yolk-shell Co₃O₄-CoO/carbon composites for lithium-ion batteries with enhanced electrochemical properties

A novel yolk-shell structured Co₃O₄-CoO/Carbon (Co₃O₄-CoO/C) composite was prepared and applied as cathode active materials in lithium ion batteries. The composites were prepared through a facile copolymerization of ionic liquid and acrylonitrile, which were used as carbon sources, followed by carbonization. The yolk-shell structure of the composite endows the electrodes with excellent cycling performance due to improved electronic conductivity, reduced strain and depressed aggregation of active materials compared with bare Co₃O₄. Thus, the Co₃O₄-CoO/C composite showed a high reversible capacity and cycling life of 590 mAh·g^-1 after 50 charge/discharge cycles at a current rate of 890 mAh·g^-1.