Preparation And Characterization Of Supercapacitor Electrodes Based On Carbon Fiber Paper

In today's society,oil,natural gas and other traditional energy sources are not only increasingly exhausted,but also cause a lot of pollution after use.In view of this situation,people's voice for the development and use of clean energy is rising day by day.Solar energy,wind energy,geothermal energy,biomass energy and other emerging renewable clean energy are being constantly developed and utilized.Nevertheless,the proportion of these new energy sources is still insufficient to support the complete transformation of human society from traditional energy to clean energy.Therefore,the development of efficient energy storage device is one of the important methods to solve the problem of energy transmission and storage.Carbon fiber paper(CFP)is a functional conductive material consisting of carbon fiber(diameter 6-7?m).The lower capacitance limits the application of CFP in the direction of the capacitor.Therefore,how to improve the capacitance of carbon fiber paper is an urgent problem to be solved.In view of the above problems,this paper provides two methods to improve the capacitance of carbon fiber paper.The main research results are as follows:(1)Using sulfuric acid solution to modification of carbon fiber paper,the hydrophobic carbon fiber paper into a hydrophilic carbon fiber paper,and then using simple vacuum suction filter method,the low concentration of graphene solution(0.2 mg/ml)impregnated in hydrophilic carbon fiber paper,the internal and surface of then the above materials for high temperature carbonization for composite electrode carbon fiber paper.The carbon fiber paper electrode prepared had a high surface capacitance(590 mF/cm~2 at 1 mA/cm~2),and maintained the initial specific capacitance of 97.9%after 3000 cycles at the current density of 20 mA/cm~2.(2)The carbon fiber paper was chemically modified by mixing concentrated sulfuric acid and nitric acid(volume ratio:3:1)which not only improved the hydrophilicity of the paper,but also greatly improved the electrical capacity of the paper;(3)10 mg cellulose nanofiber and 10 mg carbon nanotube was added into the dispersant and ultrasounded to achieve the dispersion of nanocellulose(CNF)/carbon nanotubes(CNT).Through a simple vacuum suction filter,the composite was deposited on the surface of carbon fiber paper via the effect of hydrogen bonding.Although the capacitance of the compound electrode was declined,a higher rate performance(86.3%)was achieved.Moreover,it may provide more active sites for further polymerization of polyaniline;(4)The carbon fiber paper/nanocellulose/carbon nanotube composite electrode was immersed in an acid solution of aniline,ammonium persulfate was added as initiator,and the electrochemical properties of the quaternary composite electrode prepared by polyaniline growing at different times were discussed.The results showed that the electrochemical properties of the quaternary composite electrode were superior when the growth time of the polyaniline was6h.The specific capacitance of the composite electrode reached a maximum of 1706 mF/cm~2 at the current density of 1 mA/cm~2,and the initial capacitance of 70.6%could be retained after10,000 cycles at the scanning rate of 50 mA/cm~2;the quaternary composite electrode was assembled into a symmetrical supercapacitor(using polyvinyl alcohol and sulfuric acid as solid electrolyte).The supercapacitor obtained a specific capacitance of 626 mF/cm~2,a power density of 250.3?W/cm~2,and an energy density of 87?Wh/cm~2 at a scanning rate of 0.5 mA/cm~2.