Structure of a new rotationally faulted multi-layer graphene-carbon nanoflower composite

The structure of a new carbon-carbon nanocomposite that consists of thin (<15 layers) multi-layer graphene microsheets and carbon nanoflowers (CNF) was examined by high-resolution transmission electron microscopy combined with selected area electron diffraction (SAED) analysis, and Raman spectroscopy. Both SAED and Raman analyses verified that graphene layers in the sheets were rotated to each other. A typical rotation angle in SAED analysis was 30 ± 2° but also other rotation angles (e.g., 2 ± 1°, 12 ± 2°, 19 ± 2° and 25 ± 2°) were detected. Raman analysis designated the rotation angle of 11-12° which may indicate that this is the predominant rotation angle in the composite. Both folded and free standing, unfolded edges were present in the sheets. The free standing edges were rough and no preferred chirality was found. Overlapping boundary interfaces were dominant between the graphene domains in the sheets. These features may degrade the electronic properties of the composite from the ideal values. However, the interlayer distance in the sheets was increased ∼12% compared to graphite. This, together with the wrinkled network of the sheets and the CNFs that contain nanosize (∼5-10 nm) cavities, may increase, e.g., lithium-ion insertion capacity of the composite.