Hollow Co-Co3O4@CNTs derived from ZIF-67 for lithium ion batteries

A novel hollow Co-Co3O4 coated with carbon nanotubes (CNTs) nanostructure was designed. Here, zeolite imidazolate framework-67 cubes were used as sacrificial template and carbonized under H2/Ar atmosphere along with in-situ growth of CNTs to form Co nanostructures@CNTs. Then the Co nanostructures@CNTs was treated by thermal-oxidation under air to further construct hollow Co-Co3O4@CNTs. The obtained hollow Co-Co3O4@CNTs was characterized by scanning electron microscopy, transmission electron microscopy, N2 adsorption/desorption isotherms, X-ray powder diffraction, X-ray photoelectron spectroscopy and electrochemical techniques. It was found that the hollow Co-Co3O4@CNTs cubes were wrapped by lots of CNTs. As it was used as anode materials for lithium ion batteries (LIBs), after cycling 200 cycles at 0.2 A g−1, the reversible capacity was still kept at 806.7 mA h g−1. Excellent cycle stability and Li+ storage capacity originated from the hollow nanostructures and the encapsulation of CNTs around hollow Co-Co3O4 cubes to buffer the volume change of Co3O4 and improve the electrical conductivity. Meanwhile, the increased specific surface area could effectively improve the storage of Li+. Therefore, the hollow Co-Co3O4@CNTs might have potential application in LIBs.