Synthesis And Electrochemical Performance Of 3D Coal-based Graphene And Its Composites

As a new type of energy storage device, supercapacitor is characterized by high power density, high energy efficiency and environment friendly, which performance mainly depends on the structure and properties of electrode material. In this dissertation, 3D coal-based graphite(3D-CG) and their composites with MnO2 and PANI respectively were prepared to apply to supercapacitors by a Simple hydrothermal self-assembly route with coal-based graphene oxide(CGO) as raw material. The structure-activity relationship of 3D-CG and its composites was studied. This work has a certain theoretical guiding significance for the preparation of new electrode materials and the function and conversion of coal. The main contents are given as follows:3D coal-based graphene(3D-CG) was synthesized by hydrothermal method with CGO as the precursor prepared from Taixi coal. The basic structure and composition of 3d-CG were characterized by some modern detection equipment, such as FT-IR, XRD, Raman, SEM, and TEM. The influence mechanism was studied between common aqueous electrolyte and the electrochemical properties of 3D-CG. Research indicates: 3D-CG, consisting of well-defined and cross-linked three dimensional porous structure, can effectively suppress the agglomeration of graphene in practical application. The specific capacitance of 3D-CG in 6 M KOH and 1 M H2SO4 were 248.41 F/g and 256.25 F/g when 3D-CG has an electric double layer capacitor and pseudocapacitance as a supercapacitor electrode material. 3D-CG in 1 M Na2SO4 just has faraday capacitance and the specific capacitance is 149.52 F/g.3D MnO2/coal-based graphene composites(3D-MnCG) were prepared via one-step hydrothermal self-Assembled method with MnCl2, MnO2 and CGO as raw materials. The composition and morphology of the composites were examined by XRD, TEM, SEM and Raman spectra. The electrochemical performance of 3D-MnCG were evaluated by using cyclic voltammetry, galvanostatic charge/discharge and AC impedance method. The results indicated that MnO2 was growth on the graphene nanosheets and porosity uniformly; the 3D-MnCG electrode had a maximum specific capacitance of 180.12 F/g when the CGO was 60 %. After1000 consecutive cycles, the discharge capacitance remains at 86.9 % of its initial value.3D PANI/coal-based graphene composites(3D-PCG) was prepared by the hydrothermal method using PANI and CGO as a precursor. FT-IR, XRD, Raman, SEM, TEM and other methods was used to detect the load status of polyaniline in graphene surface and the features of topography. The electrochemical performance of 3D-PCG was studied by electrochemical test methods. The results showed that PANI can be uniformly embedded into the network structure of 3D-CG. 3D-PCG has the highest specific capacitance compared with PANI and 3DCG and it can reach 663.23 F/g when the mass ratio of PANI and 3D-CG is 1:2.