Co-Co₃O₄ Embedded in Carbon Nanotube Derived from a Zeolitic-Imidazolate Framework as Anode Material for Lithium-Ion Batteries

Co and carbon nanotube (CNT) were prepared as anode materials to be used in lithium rechargeable batteries from the zeolitic-imidazolate framework-67 (ZIF-67) using the solvothermal method. By annealing ZIF-67 at different temperatures between 400 and 700 °C, the carbon framework was changed to CNTs, and Co or Co₃O₄ nanoparticles were embedded in the CNTs (Co or Co₃O₄/CNT). The Co/CNT was converted to Co-Co₃O₄/CNT by further treatment at 160 °C in air. The Co₃O₄/CNT showed high initial capacities (1582 mAh/g) but poor capacity retention during cycling. However, the air treatment of the Co/CNT at 160 °C enhanced its discharge capacity (935 mAh/g) and capacity retention during cycling.