Study On Preparation And Performance Of Supercapacitor Electrode Material Based On Carbazole-EDOT Group

As one of the main energy storage components,super capacitors are different from traditional capacitors and batteries.It has its unique advantages:large capacity,high power density,and long life.Supercapacitors are mainly divided into electric double layer capacitors and pseudocapacitors.Different from the electrode material of electric double layer capacitors,conductive polymer,as one of the main electrode materials of pseudocapacitors,has a higher specific capacity because of its redox reaction.At the same time,conductive polymers are favored among many electrode materials by virtue of their high conductivity,low cost,and environmental protection.Therefore,we choose conductive polymers as the basis for research.However,the factors affecting its production and use are poor stability,energy density has a large room for improvement,etc.,and there is still a long distance from actual production and use.In this paper,with the starting point of improving the specific capacity and cycle stability of supercapacitors as the starting point,we designed and synthesized polymer materials with carbazole-EDOT as the conjugated polymer backbone,and explored the influence of the introduction of different groups on their electrochemical performance.Activated carbon is used to prepare composite materials,and the effect on its cycle stability is studied.The main research contents are as follows:?1?Designed with carbazole-EDOT as the backbone and attached phenylnitro and anthraquinone groups to its side chains respectively,successfully synthesized carbazole-EDOT derivatives ECz E,ECz NO₂E,ECz AQE,and prepared by electrochemical polymerization Its homopolymer.Characterized by SEM,the particles of PECz E are finer and more dispersible.After calculation,the b value of PECz E is0.95,which is an obvious capacitive behavior.The b values of PECz NO₂E and PECz AQE are 0.59 and 0.66,which are between 0.5?1,which belongs to the mixed behavior of battery and capacitor electrode materials.The capacitance value of PECz E reaches 8.41 m F/cm2 at a current density of 0.1 m A/cm²,which is higher than the other two,and the specific capacitance is still 7.03 m F at a current density of 1 m A/cm²,the specific capacity remains at 83.6%,showing good rate performance.With the change of PECz NO₂E and PECz AQE from 0.1 m A/cm² to 1 m A/cm²,the capacitance value decreased from 1.52 m F/cm² to 0.49 m F/cm²,4.05 m F/cm² to 2.29 m F/cm²,respectively,and the capacitance retention rate was 32%,57%.It is proved that the introduction of different active groups will change the molecular structure,which will ultimately affect the change of its energy storage behavior,and will also have a greater impact on the energy storage level of its electrode materials.At the same time,the energy storage level of the bipolar electrode material PECz AQE with n-doping was tested at a current density of 0.5 m A/cm².Although the capacitance value is only 1.22 m F/cm²,the preliminary exploration of the preparation of bipolar materials and testing their electrochemical performance under general conditions has a high practical significance.?2?Using foamed nickel as a conductive substrate,three different conductive polymer PECz E loading composites AC/PECz E-5,were successfully prepared on the activated carbon material prepared in advance by controlling the number of electrochemical polymerization cycles AC/PECz E-8,AC/PECz E-10.Through SEM characterization,it was observed that the AC/PECz E-8 with 8 cycles of polymerization covered the surface of the activated carbon to a greater extent,with a finer morphology and more uniform dispersion.Characterized by cyclic voltammetry electrochemical test and constant current charge and discharge test,the composite material AC/PECz E-8has an area specific capacitance value of 271.32 m F/cm² at a current density of 5m A/cm²,which is higher than AC/PECz E-5,AC/PECz E-10 two composite materials226.58 m F/cm²,154.32 m F/cm².And after 1000 cycles of cyclic stability testing,the AC/PECz E-8 capacitance retention rate is 72.3%,which greatly improves the stability of pure polymer materials.It is proved that the method of preparing composite materials by controlling the growth of polymers with appropriate loading can effectively improve the defects of poor stability as a single polymer material,and the synergistic effect with activated carbon also increases the specific capacity of the material,which has certain promotion significance.