Formation of hollow spheres structures Co/CoO/ZnO@NC from metal-organic frameworks as a anode for lithium-ion batteries

Abstract

Transition metal oxides have become a potential anode material for LIBs due to their large theoretical capacity, low cost, abundant resources. However, significant volume changes and severe particle aggregation occur during charge/discharge process. In this work, it is found that the composite of dual component active TMO and single metal, and coating by doped carbon are the effective methods to improve the electrochemical performance and adapt to volume changes in storing lithium. The specific process is based on the co-precipitation of Zn and Co ions in the presence of 2-methylimidazolium salts to produce imidazolium salt frameworks (ZIFs) of bimetallic zeolites, which are then thermally decomposed to form hollow spheres structures Co/CoO/ZnO@NC. The hollow sphere uses Co as the core and CoO/ZnO@NC particles coated with nitrogen doped carbon layer as the shell. These spherical structures exhibit excellent electrochemical performance, high reversible capacity, excellent cycling stability (702 mAh/g at 100 mAg−1 after 100 cycles), and good rate capability (735 mAh/g and 515 mAh/g at 100 mA g−1 and 2000 mA g−1 respectively).