Synthesis And Electrochemical Properties Of Three-dimensional Graphene/Polyaniline Composites

Graphene is one of the most promising used electrode materials for supercapacitors because of it has many special properties,such as high electrical conductivity,high theoretical specific area and superior mechanical properties.However,the surface area of graphene cannot be fully utilized due to the aggregation of graphene.Polyaniline(PANI)is one of conducting polymers because of its enviromenetal and chemical stability,easy synthesis,high conductivity,reversible redox states and high theoretical specific peseudocapacitance.However,the volume of PANI suffers from swelling and shrinkage during charging-discharging process,resulting in the poor cycling stability.In orders to overcome those limitations,hybrid composites combining PANI with graphene have been developed.This paper adopts the method of in-situ polymerization,regulates the composition and structure of the two components,and obtains the three-dimensional graphene/polyaniline composite materials with excellent electrochemical properties.The main contents and results are as follows:(1)By using the method of hydrothermal reduction,the graphene oxide dispersion(GO)formed the self-assembly of three dimensional graphene aerogels(GA),and the characterization was performed by XRD,FT-IR,Raman,TGA,SEM and other methods.The electrochemical properties of aerogels are discussed in this paper.The research results show that when the concentration of graphene oxide dispersion(GO)is 7 mg/mL,the graphene aerogels get the best electrochemical properties.It has rectangular CV curve,and shows the performance of electric double layer capacitance,specific capacitance values of 291 F/g,which offers very little resistance and excellent cycling stability.After 2000 times cyclic charge and discharge,the capacitance remained 98% of the initial value.(2)Through the method of in situ polymerization,the aniline monomer was loaded to the graphene aerogels,and the 3D graphene/PANI aerogel(GAP)was got.The structure and composition of polyaniline and GPA was studyed by FT-IR,Raman,XRD,SEM and TEM.The electrochemical properties were also analyzed.Research results show that the addition of polyaniline changed the constitute of aerogels,making the composite aerogel electrochemical performance greatly improved.The composite material shows not only double layer capacitance but also faradaic pseudocapacitance,which specific capacitance could reach 618 F/g under the electric current density of 1 A/g,possessing good ratio performance.The composite material also possesses excellent cycle stability which capacitance retains 89% after the current density of 10 A/g cycle discharge after 2000 laps.(3)Through the method of in-situ polymerization,the graphene/polyaniline composite material,which used polystyrene microspheres as template,was prepared as self-assembly.The porosity of aerogel was changed when PS microspheres were removed after added.The capacitance performance of the composites was improved and the specific capacitance can reach 498 F/g under the current density of 1 A/g.So the composite material has a good ratio performance and small internal resistance.The composite material also has excellent cycle stability which capacitance retain 91% after cycle discharge 2000 laps under the current density of 10 A/g.