Self-assembly of corn-like Co3O4 from nanoparticles induced by graphene wrinkles and its application in lithium ion batteries

Abstract

Graphene wrinkles were ubiquitous during the preparation and application. The wrinkles can affect the interfacial interactions between graphene and metal oxides in composites. Here, a high density corn-like Co₃O₄/graphene hybrid material (Co₃O₄/GNSs) was prepared by direct pyrolysis of Co(NO₃)₂·6H₂O on graphene nanosheets (GNSs) through self-assembly induced by graphene wrinkles. The morphology and structure of the as-prepared Co₃O₄/GNS composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Co₃O₄/GNSs, used as an anode material, exhibited a reversible capacity of 911 mA h g⁻¹ for the first charge process and 1060 mA h g⁻¹ after 50 cycles at 50 mA g⁻¹, respectively. At 500 and 1000 mA g⁻¹, the reversible capacities could reach 763 and 561 mA h g⁻¹, which were 84% and 62% of that at 50 mA g⁻¹. The high capacity and excellent rate performance should be attributed to the synergistic effect between Co₃O₄ and GNSs. The presence of GNSs can act as a substrate for the growth of corn-like Co₃O₄ and a highly conductive matrix for good contact between GNSs and Co₃O₄ nanoparticles. In particular, the presence of wrinkles can provide a buffer for the volume expansion of Co₃O₄. In turn, the presence of Co₃O₄ can also reduce the restacking of GNSs.