Nanoporous Composites of CoO x Quantum Dots and ZIF-Derived Carbon as High-Performance Anodes for Lithium-Ion Batteries

Transition-metal oxides are attracting considerable attention as anodes for lithium-ion batteries because of their high reversible capacities. However, the drastic volume change and inferior electrical conductivity greatly retard their widespread applications in lithium-ion batteries. Herein, three-dimensional nanoporous composites of CoO x (CoO and Co3O4) quantum dots and zeolitic imidazolate framework-67-derived carbon are fabricated by a precipitation method. The carbon prepared by carbonization of zeolitic imidazolate framework-67 can greatly enhance the electrical conductivity of the composite anodes. CoO x quantum dots anchored firmly on zeolitic imidazolate framework-67-derived carbon can effectively inhibit the aggregation and volume change of CoO x quantum dots during lithiation/delithiation processes. The nanoporous structure can shorten the ion diffusion paths and maintain the structural integrity upon cycling. Meanwhile, kinetics analysis reveals that a capacitance mechanism dominates the lithium storage capacity, which can greatly enhance the electrochemical performance. The composite anodes show a high discharge capacity of 1873 mAh g–1 after 200 cycles at 200 mA g–1, ultralong cycle life (1246 mAh g–1 after 900 cycles at 1000 mA g–1), and improved rate performance. This work may provide guidelines for preparing cobalt oxide-based anodes for LIBs.