Fabrication Of Flexible Graphene Electrode Array And Its Application In Supercapacitors

Supercapacitor,also called electrochemical capacitor,is a new type of high efficiencyenergy storage device between ordinary capacitors and batteries.It has many advantages,such as fast charging,high energy density and power density,friendly environment,long service life and so on.It has been widely used in the fields of digital products,backup energy systems and electric vehicles.In recent years,with the rapid development of wearable devices and portable electronic devices,miniaturized portable devices are developing in the direction of "light,thin,short and small",which has prompted the urgent need for the corresponding micro / nano power sources.As a result,the micro supercapacitor emerged as the times require.It is a micro high power electrochemical energy storage device.It has the advantages of small volume,high power density,and can provide the peak power of effective power in a moment.As an energy storage device with portability and flexibility,flexible planar supercapacitors have attracted wide attention and research.On the basis of the paper substrate,the flexible graphene electrode array and supercapacitor were prepared by electrochemical stripping of graphene as the raw material.Scanning electron microscopy(SEM)and electrochemical workstation(Solartron 1260)were used to characterize and analyze the electrical properties,micromorphology,flexible properties and cyclic properties of the electrode arrays and supercapacitors.The results of the study on the electrode array show that the graphene electrode still maintains the porous fiber structure of the paper base,and its electrical properties are closely related to the micromorphology.The microelectrode array prepared by the stereoscopic coating method has the three-dimensional conductivity and the good flexibility.The electrode conductance retention rate is up to 97% when the electrode is bent 180 degrees.After 2400 cycles of bending,the conductance retention rate is still above 90%,indicating the good flexibility of the electrode array.The electrochemical measurement and characterization of supercapacitors were carried out by cyclic voltammetry.The capacitance of the capacitor was up to 5.87 m F/cm2 at 10m V/s scanning rate,and the capacitor capacity retention rate was 96% after the capacitor was bent60,90,120,160 and 180 degrees.Using the constant current charge and discharge test,the capacitor area is 6.43 m F/cm2 and the capacitance is higher than the capacitance at the currentdensity of 0.1m A/cm2.Under the 0.2m A/cm2 current density,the capacitor retention rate is still more than 90% after 2000 cycles.It fully demonstrates the excellent flexibility and cycling performance of capacitors.In addition,the relationship between the electrical properties,flexibility,microstructure and supercapacitor performance of the electrode array is characterized and analyzed.The results show that the electrical properties of the graphene electrode array are closely related to the flexible performance of the electrode and the energy storage performance of the capacitor:The compact electrode has a small resistance and high flexibility,but the compact structure hinders the infiltration of the electrolyte to the electrode and reduces the active area of the stored charge,resulting in a decrease in the energy storage performance of the supercapacitor.