Preparation Of Coal-based Graphene/carbon Nanofiber Composite And Its Electrochemical Performance

Supercapacitors hold promise for being the most promising modem energy storage systems due to their high power density,short charging time,and environmental friendliness.The electrode materials are the key factors affecting the performance of supercapacitors.The carbon material is considered as an ideal electrode material.Therefore a coal-based graphene material is prepared by using coal which is rich in nature as a raw material,then compound it with carbon nanofibers fabricated by electrostatic spinning technology to make the electrode material expected that high-performance electrode material with large specific surface area,high aspect ratio and low resistivity.In this dissertation,coal-based graphene/carbon nanofiber series composites were prepared by impregnation method and mixed spinning method,respectively,and applied to supercapacitors.The main research results include the following three aspects:(1)Coal-based graphene oxide(CGO)was gained using coal as raw material.Then using CGO,PAN and PMMA as raw materials,coal-based reduced graphene oxide loaded porous carbon nanofiber composites(CG/PCNF)were successfully prepared by electrospinning combined with heat treatment process.The morphology and structure of the materials were analyzed by SEM,TEM,physical adsorption instrument,the electrochemical workstation and land battery workstation were used.Studies have shown that CG/PCNF was successfully prepared and the specific capacitance of the supercapacitor electrode material in a 6 M KOH solution with a three-electrode system can reached 225.1 F/g.(2)PAN and PMMA,obtained by electrostatic spinning and processed pre-oxidation treatment,were used as substrate.CGO was used as impregnation liquid and it was deposited the surface of PAN/PMMA,then adopted high-temperature processing to get CG@PCNF.The morphology and structure of the CG@PCNF were used to analyze through SEM,TEM,and physical adsorption.Electrochemical performance of the composites was analyzed using electrochemical workstations and land battery workstation.Studies have shown that the specific capacitance of CG@PCNF can reach 267.2 F/g in a 6 M KOH solution under a three-electrode system,as a supercapacitor electrode material,and the specific capacitance can still retain 98.01%after 5000 charging-discharging cycles.(3)Faraday tantalum capacitor supercapacitors based on transition metal oxides are higher than pure carbon material due to redox reactions.In order to obtain a composite material with better electrochemical performance,PAN and SnCl2 were used as a raw material to prepare CG@CNF/SnO2 by electrospinning,pre-oxidation,CG impregnation,carbonization,roasting,and pickling.The physical adsorption instrument was used to analyze the morphology and structure of the material,and the electrochemical performance of the composite material was analyzed using electrochemical workstation and land battery workstation.Studies have shown that the CG@CNF/SnO2 composites exhibit good capacitive behavior with a high specific capacitance of 313.4 F/g at a current density of 1 A/g in 6 M KOH electrolyte and kept 97.18%and 97.41%of its capacitance after 5000 and 8000 charging-discharging cycles,respectively.