Study On Preparation And Performance Of Polyaniline-Carbon Fiber Paper-Based Supercapacitor Electrode Material

One of the key factors to improve the electrochemical performance of electrode materials is to improve its electrical conductivity,that is,the low equivalent series resistance.This resistance is needed for fast energy storage,and the equivalent series resistance of supercapacitor is the lowest among all energy storage devices at present,so it has attracted much attention.Flexible supercapacitor that the electrode materials have certain stiffness and softness to ensure that they can not only be used under normal circumstances,but also show good electrochemical performance under special circumstances such as cripping,folding and wearing.However,for traditional supercapacitors,electrode materials do not have softenness,the distribution of active substances also is not uniform,easy to fall off,and the use of adhesives lead to poor electrochemical performance of the electrode.Although carbon fiber has high electrical conductivity,its surface is smooth and has few active groups,resulting in poor performance of paper formation,so it needs to be compounded with other hydrophilic fibers.Traditional papermaking plant fibers are not resistant to acid corrosion,so this paper uses a mixture of aramid pulp and carbon fiber to prepare carbon fiber paper with good physical properties.As the insulation of aramid pulp reduces the conductivity of the material,acid-doped polyaniline can make up for the defect.In this thesis,starting from the uniformity of active material distribution,two different preparation methods are used to prepare highly conductive polyaniline-carbon fiber paper-based composites,and based on the mixed metal oxide（MnO₂）preparation of a wide range of voltage window,high specific capacitance and high power density and good stability,long service life of the super capacitor paper base flexible electrode materials.First of all,The stepwise in-situ polymerization method was used to make polyaniline grow uniformly on the carbon fiber paper substrate.The morphology,surface structure and element changes of the material was characterized by SEM,FTIR and EDS.The results showed that under the conditions of mass fraction of carbon fiber of 20%,APS concentration of 0.375mol/L,n_{（aniline）}∶n_{（hydrochloric acid）}=2∶1,reaction time of 12h and immersion time of 1min,the polyaniline-carbon fiber paper-based composite material（PANI-CP）had the best conductivity.Compared with those of carbon fiber base paper（CP）,the conductivity of PANI-CP was 5.435S/cm,which was an improvement of 249.9%,the tensile index was27.665N·m/g,and the physical strength increased by 37.3%.Compared with the Polyaniline-carbon fiber paper-based composite material（L-PANI-CP）prepared by in-situ polymerization method,the conductivity of PANI-CP was increased by 85.9%and the total color difference（DE）decreased by 66.0%.Secondly,Surface modification method is used to prepare polyaniline-carbon fiber paper-based composite material,that is PANI-AP was prepared by modifying polyaniline（PANI）on the surface of aramid pulp（AP）,and then blended with carbon fiber to prepare paper-based material（PANI-AP/CP）with excellent electrical conductivity by papermaking wet-lay technique.The morphology,conductivity and PANI distribution uniformity of PANI-AP/CP were characterized,and the effects of environmental humidity,temperature,p H,and storage time on the electrical conductivity of PANI-AP/CP were explored.The results showed that after PANI modification,the surface roughness and crystallinity of AP increased,and the appearance of diffraction peaks of conductive polyaniline containing quinone structure showed that polyaniline was successfully modified on aramid pulp.For the PANI-AP/CP prepared by this method,both the properties and the distribution uniformity were improved.Compared with the carbon fiber paper substrate（CP）and the L-PANI-CP,the conductivity of PANI-AP/CP（3.937 S/cm）increased by 153.5%and 34.6%,respectively,and the average total color difference（DE）was reduced by 74.9%compared with L-PANI-CP.Then,the two preparation methods are compared with physical properties and electrochemical properties as measurement standards,and the best preparation method and process are finally obtained.The results show that:Compared with PANI-AP/CP,PANI-CP has better physical strength,layered porous structure,high conductivity and better electrochemical performance.The specific capacitance of PANI-CP can reach 393.7 F/g,and it has a relatively symmetrical CV radian curve and an obvious reversible reaction peak of polyaniline REDOX.It can provide a simple and feasible preparation method and theoretical basis for polyaniline-carbon fiber composite material as a supercapacitor electrode material.Finally,It has become an unfavorable trend to make the energy storage device develop in the direction of soft and wearable.carbon fiber paper substrate（CP）was prepared with light-weight,flexible,and foldable while also having low internal resistance,a uniform pore size distribution,and high porosity by papermaking wet-lay technique.Theγ-MnO₂was wrapped with PANI to form a core-shell structure,and a stepwise in situ polymerization method was adopted to deposit the core-shell structure uniformly on the CP substrate.This process yielded a flexible electrode material,calledγ-MnO₂-PANI-CP.Results showed that theγ-MnO₂-PANI-CP electrode had a high specific capacitance of 642.5 F/g at a current density of 1 A/g,which was attributed to the PANI.Theγ-MnO₂-PANI-CP electrode material had a high energy density of 114.2 Wh/kg at a power density of 798.6 W/kg.The electrode retains 81.3%of the initial capacitance after 5000 cycles,demonstrating high cycling performance.