Abstract:

Transition metal oxides have been intensively studied as potential anode materials for the next generation lithium-ion batteries due to their high theoretical capacity， low cost and higher safety. Herein， the nano-cubic Cu₂O was fabricated through simple liquid-phase method followed by the self assembly of ZIF-67/ZIF-8 bi-metal organic framework（MOF）， then the hierarchical porous Cu₂O/Co₃O₄@C heterostructured composite material with Co₃O₄ and N-doped carbon as double shell was successfully constructed. XRD， SEM， TGA， BET， Raman spectra and XPS characterization proved the successful engineering of the heterostructured Cu₂O/Co₃O₄@C composite material. Benefiting from the double-shell and hierarchical porous construction， the volume expansion of the composite material during cycling was effectively restrained. The SEM images after even 100 cycles proved the maintaining of the original morphology and structure of the composite material. The sufficient electrolyte infiltration owing to the porous surface structure， the built-in electric field at the heterostructure interface and the coating of defective N-doped carbon mutually enhance the electronic and ionic conductivity and facilitate the reaction kinetics. The synergistic effects of heterostructure design， morphology regulation， porous properties and N-doped carbons coating endow the Cu₂O/Co₃O₄@C composite material with excellent electrochemical performance. An as high initial discharge capacity as 2065 mA·h/g at 0.1 A/g and reversible discharge capacity of 360 mA·h/g at 2 A/g are delivered， and the stable discharge capacity of 550 mA·h/g maintains after 350 cycles at 1 A/g.

Key words: Hybrid anode material, Heterostructure, Bi-ZIF, N-Doped carbon, Synergistic effect