Preparation And Energy Storage Properties Of Three Electrode Materials Based On Graphene Gel

Supercapacitor has high charge storage capacity,fast charging and discharging speed,and long cycle charge discharge life.It is considered to be one of the most promising charge storage devices.As the core component of supercapacitors,electrodes can directly affect the electrochemical performance of supercapacitors.Therefore,the preparation of electrode materials with good electrochemical performance is an important prerequisite for assembling high-performance supercapacitors.In this paper,graphene aerogels(GA)was prepared by sol-gel method.The effect of p H value in precursor fluid and the mass fraction of graphene oxide(GO)on the energy storage properties of GA materials were studied.The microstructure and morphology of GA was characterized by X-ray diffraction,X-ray photoelectron spectroscopy,nitrogen adsorption-desorption analysis and scanning electron microscopy.The electrochemical performance of GA was tested by cyclic voltammetry,constant current charge-discharge and electrochemical impedance spectroscopy.The results showed that the size and quantity of cluster particles in GA was affected by the p H value and go mass fraction in the precursor,and further affected the three-dimensional structure of GA.When the p H value was 6.3 and the mass fraction of go was 1%,the specific surface area of GA was 530 m²/g and the specific capacitance was364 F/g at 1 A/g current density.At the same time,hydrothermal and in-situ polymerization reactions were used to produce a molybdenum aerogel(MoO₃)and polypyrrole(PPy)coated graphene aerogels composite materials(MoO₃/GA@PPy).The shape and structural properties of PPy,MoO₃/GA and MoO₃/GA@PPy were studied by X-ray diffraction,Fourier transform spectroscopy,Raman spectroscopy,photoluminescence spectroscopy,scanning electron microscopy and X-ray photoelectron spectroscopy.The formation process of ternary nanocomposites(MoO₃/GA@PPy)was revealed.The electrochemical properties such as capacitance,specific capacitance retention rate,cyclic stability and impedance of MoO₃/GA@PPy under different current loads were also discussed.Obviously,the electrochemical performance of MoO₃/GA@PPy was better than that of GA.The maximum specific capacitance of MoO₃/GA@PPy was 1788 F/g when the current density was 1 A/g.In addition,GA and MoO₃/GA@PPy were assembled into water system and solid state symmetric supercapacitors respectively.At 1 A/g,the specific capacitance of the two water system capacitors were 98 F/g and 139 F/g,respectively,and the specific capacitance of solid state capacitors was 122 F/g.Two of the water system capacitors have high coulomb efficiency and cycle stability,which fully proves that MoO₃/GA@PPy composites can be used for supercapacitors.