Preparation And Electrochemical Energy Storage Of Organic/Inorganic Hybrid Films Based On Multi-Element Doped Graphene Composites

The two-dimensional graphene has the advantages of large surface area,good conductivity,high mechanical properties and easy functionalization,and has broad application prospects in the field of supercapacitor electrode materials.Graphene is prepared by top-down and bottom-up methods.The redox method is to oxidize graphite into graphene oxide(GO)with oxygen-containing functional groups such as carbonyl and carboxyl groups.Reduction and layering of GO can obtain graphene.Further chemical and physical modification of GO and graphene can improve their performance and multi-functionalization.This paper uses different organic conjugated molecules to modify graphene to optimize and improve the electrochemical energy storage performance of graphene-based supercapacitors.The first part selects acridone and its derivatives including acridone,N-acetate potassium acridone,N-acetate sodium acridone,etc.as organic electrochemical active molecules,which were combined with graphene by hydrothermal method to obtain composite active materials.The effects of the conjugation length of organic molecules and kind of cation species on the energy storage performance of supercapacitors were studied respectively.The experimental results show that:Compared with other composite materials,the composite material YDYSK@RGO-1 based on N-acetate potassium acridone and graphene has relatively higher specific capacitance.The specific capacitance at a current density of 0.5 A/g is 92 F/g.This is due to the strong π-π interaction between NV-acetate potassium acridone and graphene,which can better inhibit the stacking of graphene.When the mass ratio of N-acetate potassium acridone and graphene was 1:1,the specific capacitance of the composite material was the highest.Adding too much N-acetate potassium acridone will reduce the conductivity of the composite,and adding too little will not be enough to inhibit the stacking of graphene.When YDYSK@RGO-1 is used as an electrode material for long-term charging and discharging,the electrode material is gradually activated and the electrolyte fully penetrates into the electrode material,which causes the specific capacitance of the material to be increased by 66%.Since the redox reaction that occurs during the reaction of acridone derivative materials is not completely reversible,the specific capacitance is lower than that of other pseudocapacitance materials.The second part uses the self-polymerization reaction of dopamine hydrochloride with sodium molybdate to generate flower-like Mo-Polydopamine(Mo-PDA),which is combined with graphene through hydrothermal reaction to obtain graphene-based composite materials.The composite material is used as the electrode material for the supercapacitor,and the influence of the doping amount of Mo-PDA on the energy storage performance of the supercapacitor is studied respectively.In the liquid supercapacitor using 6 M KOH solution as the electrolyte,when Mo-PDA and graphene are composited at a mass ratio of 1:2,that is,the composite material Mo-PDA@RGO-0.5,the electrochemical energy storage performance is the highest.The discharge time is as high as 910 s.At a current density of 0.5 A/g,the specific capacitance of the composite Mo-PDA@RGO-0.5 is 455 F/g,and even at a current density of up to 20 A/g,the specific capacitance can keep 274 F/g.Appropriate addition of Mo-PDA can significantly improve the capacitance performance of supercapacitors.Too much Mo-PDA on the surface of graphene will not only reduce the electrical conductivity of the composite,but also reduce the effective ion diffusion path of graphene.The lack of Mo-PDA leads to the limited introduction of pseudocapacitance,which cannot maximize the energy storage performance.