Co/ZnO/Nitrogen-Doped Carbon Composite Anode Derived from Metal Organic Frameworks for Lithium Ion Batteries

Through high-temperature sintering and carbonization, two Co/ZnO nitrogen-doped porous carbon (NC) composites derived from ZIF-8 and ZIF-67 were manufactured for use as anodes for Li ion batteries: composite-type Co/ZnO-NC and core-shell-type Co@ZnO-NC. X-ray diffraction analysis, scanning electron microscopy, and the Brunauer-Emmett-Teller (BET) method were performed to identify the pore distribution and surface morphology of these composites. The findings of the BET method indicated that the specific surface area of Co/ZnO-NC was 350 m²/g, which was twice that of Co@ZnO-NC. Electrochemical measurements revealed that Co@ZnO-NC and Co/ZnO-NC had specific capacities of over 400 mAh g^-1 at a current density 0.2 A g^-1 after 50 cycles. After 100 cycles, Co/ZnO-NC exhibited a reversible capacity of 411 mAh g^-1 at a current density of 0.2 A g^-1 and Co@ZnO-NC had a reversible capacity of 246 mAh g^-1 at a current density of 0.2 A g^-1. The results indicated that Co/ZnO-NC exhibited superior electrochemical performance to Co@ZnO-NC as a potential anode for use in Li ion batteries.