Preparation Of Multi-doped Graphene Aerogel And Its Application In Supercapacitors

In this paper,multi-layer graphene oxide,boric acid,sodium borohydride,urea,thiourea and boron phosphate were used as raw materials to prepare graphene oxide aerogel(GOA),boron-doped graphene aerogel(BGA),boron/nitrogen co-doped graphene aerogel(BNGA),boron/nitrogen/sulfur co-doped graphene aerogel(BNSGA)and boron/nitrogen/sulfur/phosphorus co-doped graphene aerogel(BNSPGA)by simple hydrothermal method and freeze-drying technique.The morphology and structure of the above materials were characterized by scanning electron microscope,physical adsorber,x-ray photoelectron spectroscopy,x-ray diffraction and raman spectroscopy.The results of characterization show that the multi-element heterogeneous elements are successfully incorporated into the graphene skeleton,and the aerogel exhibits a three-dimensional interconnected pore structure.The GOA,BGA,BNGA,BNSGA and BNSPGA were fabricated as working electrodes.Cyclic voltammetry,galvanostatic charge-discharge,electrochemical impedance spectroscopy and cyclic stability were measured in three-electrode system and two-electrode system.After testing,the capacitance properties of the electrodes were evaluated.In the three-electrode test system,at a current density of 1 A g-1,the specific capacitances of the GOA,BGA,BNGA,BNSGA and BNSPGA are 148.6 F g-1,165.2 F g-1,202.2 F g-1,235.0 F g-1,and 240.3 F g-1,respectively.In the two-electrode test system,at a current density of 1 A g-1,the energy density are 1.75 Wh Kg-1,2.01 Wh Kg-1,3.37 Wh Kg-1,5.11 Wh Kg-1,and 6.86 Wh Kg-1,respectively.At the same time,the electrochemical impedance data also shows that the conductivity of electrolyte ions and electrons in the electrode materials gradually increased.The test rules under these two systems are basically the same.Among the above aerogel materials,the specific capacitance(240.3 F g-1)and the capacity retention ratio(96.0%)of the BNSPGA electrode are the highest values,so the quaternary heterojunction-doped BNSPGA is the best electrode material.