Synthesis, Formation Mechanism And Electrochemical Performance Of Graphene By Co-Pyrolysis

As the youngest member of carbon materials, graphene has attracted everyone's attention. Particularly in 2010, Geim won the Nobel Prize in chemistry because he stripped out graphene from graphite for the first time, pushing the research to a new high.Graphene is the thinnest material known in the world, and its mechanical, thermal, electrical, optical, etc. all have excellent performance, but the yield of conventional synthetic methods is not large, which hinders its industrial Application. This paper found a new way to prepare a mass of graphene in high quality, and the samples were analysed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FI IR) and Raman spectroscopy. In order to test the electrochemical performance, the graphene has also been dealt as anode materials for lithium-ion battery charge and discharge test and electrochemical cyclic voltammetry test.Studies have shown that this method can synthesize graphene in high yield, by pyrolysis of ferrocene and 1,2,4-trichlorobenzene mixture. It can prepare about 8 g with the carbon conversion rate of 42%. It features large output, much more than traditional methods; large layers (～10μm) and less sheets (3～5 layers); good crystallinity and less defects. In addition, the paper has analyzed product yield and morphology due to the changes in temperature and raw materials:(1) with increase of reaction temperature, it has improved product purity and crystallinity and decreased the detect; (2) with increase of carbonization temperature, the crystallinity of graphene has increased and the interlayer spacing has increased firstly and then decreased, with a maximum in 700℃; (3) finding out the optimal ratio of 1:1; when 1,2,4-trichlorobenzene content decreases, the product yield decreases with carbon source, but morphology changes are more apparent, indicating chlorine content will affect the product morphology; when ferrocene content decreases, the output has big declines, but no signifacant changes in morphology, indicating that the catalyst has greater impact on product yield; (4) in addition, the blank and contrast samples have shown that chlorine is key factor in the control of morphology. So the paper have prepared different carbon materials of carbon nanotubes, carbon nanoribbons and carbon nanospheres, with the changes of chloric carbon source, so as to infer the mechanism of synthesis of graphene and the role of chlorine.Moreover, the test result obtained by electrochemical performance are also gratifying:under the current density of 50 mAh·g-1, the graphene electrode exhibits an initial discharge capacity of 611 mAh·g-1; for cycle performance increased firstly and then went down when carbonization temperature rose, it got a best result at 700℃,413 mAh·g-1 reversible capacities. That is because the improvement of crystallinity and interlayer space has optimized the capacity of lithium ion intercalation and detachment.