Preparation And Properties Of Conductive Polymer Composite And Its Application In Supercapacitor

Supercapacitor devices have many advantages,such as long cycle life and high power density,so they have broad application prospects in the field of energy storage.The energy density and charge/discharge properties of supercapacitors have become a hot topic in this field.It is a key to find an electrode material with high specific capacity and stable performance and to expand the potential window.Based on conducting polymers,this paper used the electrochemical deposition method to produce a variety of different conductive polymer electrode materials.On raising the capacitance value and electrochemical properties,this paper discussed the influence of different mole ratio and different cycles on electrochemical performance.The preparation of a series of graphene conducting polymer composites was carried out by using the mechanical strength,electron conduction and specific surface area of graphene.The morphology,microstructure,component and electrochemical properties of the composite electrode were characterized,and the composite electrode was assemble into symmetric and asymmetric components,the electrochemical performance of components were studied.The main contents are summarized as follows:(1)Electrochemical deposition of porous polyaniline was performed on the substrate of stainless steel and carbon fiber cloth.The capacitance performance of polyaniline was compared,and the polyaniline/CFC electrode provided higher capacitance due to the high porosity of polyaniline.The maximum capacity was obtained by changing the concentration of aniline monomer.The ideal condition was the concentration of 0.15 M aniline and 0.1 M H2SO4,which can obtain a high capacitance of 1600 F g-1,and the surface capacitance was reached up to 3.3 F cm-2.The symmetrical supercapacitor assembled has 23.35 Wh kg-1 energy density and 622.45 W kg-1 power density.After 1000 times constant current charge discharge,the specific capacitance retention rate was 76%.(2)The polyaniline/reduced oxided grapheme(rGO)composite electrode was prepared by two methods:layer by layer self assembly and sandwich type.The self assembled layer electrode has higher specific capacitance,lower equivalent series resistance and higher capacitance retention rate.The polyaniline/graphene composite electrode prepared by this method has the advantages of uniform structure,stable performance and so on.The specific capacitance of polyaniline/graphene composite electrode at different assembly layers shows that the specific capacitance of the electrode material containing 12 layers of polyaniline was the largest.When the current density was 2 mA/cm2,the specific capacitance was 558 F/g and the surface capacitance was 1.32 F/cm2.When the symmetrical device was assembled at 1 mA/cm2,the power density was 746.5 W kg-1 and the energy density was 19.8 Wh kg-1.After 5000 constant current charge and discharge,the ratio of specific capacitance was 97.6%.(3)When the 10 layer of pure polypyrrole(PPy)was prepared,the maximum specific capacitance was obtained.The specific capacity of the current density at 1 A/g is 484 F g-1.Then the PPy/rGO nanocomposites were prepared with CFC matrix as a template,and the influence of the number of deposition cycles on the electrochemical properties was also investigated.Research showed that when the composite layer was 16 cycles,the PPy/rGO composite electrode has good electrochemical properties,the specific capacitance can reach 490 F g-1,compared with pure PPy,the specific capacitance of the composites by the addition of graphene did not decrease,showing good capacitance performance.The introduction of graphene optimizes the mechanical properties of PPy.After 5000 constant current charging and discharging,the capacity retention rate was 85%.When assembled into a symmetrical device at 1 mA/cm2,the specific electric capacity can reach 205 F g-1,and the energy density was 16.4 Wh kg-1.(4)A series of PEDOT was obtained by electrochemical polymerization of 3,4-thiophene under different cycles.When the composite layer was 18 laps,the composite material can make full use of the large specific surface area of rGO and the network structure formed,so that the PEDOT/rGO complex has better electrochemical capacitance characteristic.The value of specific capacitance value can be reached 125 F g-1 which was 10.4 times higher than the capacitance of the pure PEDOT material(12 F g-1).After 3000 constant current charging and discharging,the capacity retention rate was 83.6%.(5)In order to improve the working potential window,we took flexible PANI,PANI/rGO,PPy,or PPy/rGO as positive pole and CFC,PEDOT,PEDOT/rGO as negative pole,and were assembled into a new type of asymmetric supercapacitor.The energy density of optimized PANI/rGO//PEDOT/rGO asymmetric devices was 36.35 Wh kg-1,the corresponding power density was 422.15 W kg-1.Meanwhile,asymmetric devices have excellent cycle stability;the capacitor retention rate was still 101%after 5000 cycles.Research shows that these new types of capacitors achieve a large potential window(1.6 V),high energy density,power density and cyclic stability.The commercial AC/NiOOH system has an energy density of about 20 Wh kg-1,the capacitor retention rate was 90%after 2000 cycles.We developed an asymmetric super capacitor that was superior to the AC/NiOOH system.The assembly of asymmetric devices plays a vital role in improving the performance of supercapacitors,making it a potential energy storage device.