Preparation And Performance Of G-C₃N₄/Graphene-based Flexible Supercapacitor

Recently,with the emergence of flexible electronics concepts,models and products,flexible electronic devices have gradually appeared in the public field of vision such as flexible solar cells and flexible lithium batteries.Among them,flexible supercapacitors with fast charge and discharge and ultra-long service life have become research hotspots,and graphene-based materials have been popular with high conductivity and high specific surface area material.However,graphene has strong?-?bonds and Van der Waals forces,which can cause irreversible agglomeration between graphene layers.The compact structure caused by this accumulation will reduce the specific surface area and reduce its storage capacity,which can be alleviated by adding spacers.In this paper,g-C₃N₄ with high N content,no pollution,and low cost is selected as the spacer of graphene-based materials,and rGO/g-C₃N₄ composite materials are used as electrode materials for supercapacitors to prepare a variety of flexible supercapacitors.The main content of the paper and the corresponding results are as follows:?1?Prove that g-C₃N₄ doped graphene materials have excellent properties and can be used as electrode materials for supercapacitors.This paper selected a typical thermal condensation reaction and prepared g-C₃N₄ with urea and melamine as precursors.By mixing with graphene solution,hydrothermal reduction and freeze-drying,a 3D porous structure composite was obtained.The material was ground and coated on foamed nickel for three-electrode test.It was concluded that the performance of preparing g-C₃N₄-doped graphene with urea as the precursor was higher than pure graphene electrode material performance.?2?Prove the applicability of rGO/g-C₃N₄,acidified carbon fiber was used as a flexible substrate,the method of hydrothermal synthesis was used to load rGO/g-C₃N₄on the surface of carbon fiber,change the mixing ratio of rGO/g-C₃N₄ and compared with the electrochemical performance of rGO/g-C₃N₄ and CF,it was concluded that the performance is best when the ratio of rGO/g-C₃N₄ was 4:1,and the performance of the one-dimensional flexible device composed of PVA-KOH electrolyte can be reached63mF/cm².?3?A paper-like rGO/g-C₃N₄ electrode material was prepared by suction filtration and thermal reduction,named GNP.With the change of the reducing atmosphere conditions,it was found that the performance of the electrode material which obtained by reduction under nitrogen atmosphere was much lower than which under air atmosphere.By XPS analysis,it was speculated that g-C₃N₄ hindered the reduction of rGO under nitrogen atmosphere.And the performance of the two-dimensional flexible supercapacitor assembled with PVA-KOH electrolyte can reach 425 mF/cm².No matter whether it is a three-electrode test or two-electrode test of one-dimensional fiber and two-dimensional paper-like flexible devices,g-C₃N₄ can effectively prevent graphene from stacking.g-C₃N₄ is a good spacer and can improve the performance of electrode materials.