Studies On Construction Of Polypyrrole@transition Metal Compounds/cellulose Fibers Flexible Electrode Material And Its Properties

In this thesis,flexible porous cellulose fibers(CFs)were chosen as the substrates,high-capacitance transition metal molybdate(MMoO4),cobalt ammonium phosphate(NH4CoPO4)and high-conductivity polypyrrole(PPy)were chosen as electroactive materials.PPy@MMoO4/CFs and PPy@NH4CoPO4/CFs paper-based flexible supercapacitor electrode materials were prepared by the two-step in-situ method.The composite materials were characterized and analyzed by SEM,XRD,FTIR,and XPS,proving that the two types of composite materials were successfully prepared.Taking different transition metal molybdates(MnMoO4,CoMoO4,NiMoO4,CuMoO4,ZnMoO4)as the main research objects,we tested and analyzed the conductivity and electrochemical performance of the prepared PPy@MnMoO4/CFs flexible composite electrode materials,and discussed the influence of the types of molybdate on the conductivity and electrochemical performance.The experimental results showed that all five molybdates can significantly increase the specific capacitance of paper-based flexible composite electrode materials using CFs as a template.Among them,the PPy@CoMoO4/CFs flexible composite electrode material constructed with CoMoO4 had a higher conductivity and a optimal electrochemical performance.The flexible composite electrode material had a specific capacitance of 579.7 F/g at a current density of 0.2 A/g,which was 2.19 times that of PPy@CFs.Therefore,we think that Co ion has a higher activity.Because of PPy@CoMoO4/CFs flexible composite electrode material had the best electrochemical performance,so we reserched it emphatically.Using the temperature of the synthesis of CoMoO4 and the concentration of Co(NO3)2·6H2O as variables,five gradients were set respectively to explore the influence of the variables on the conductivity and electrochemical performance through the control variable method.The results of two experiments showed that when the temperature of the synthesis of CoMoO4 was 80? and the concentration of Co(NO3)2·6H2O was 0.05 M,the prepared PPy@CoMoO4/CFs flexible composite electrode material had the best electrical conductivity and electrochemical performance.The specific capacitance was 570.3 F/g at a current density of 0.2 A/g,which was 2.15 times that of PPy@CFs.In order to further evaluate the electrochemical performance of PPy@CoMoO4/CFs flexible composite electrode materials,we conducted a cycle stability test analysis on the above mentioned PPy@CoMoO4/CFs with the best performance and the blank PPy@CFs.The experimental results showed that after 1000 charge-discharge cycles at a current density of 3 A/g,the initial specific capacitance of PPy@CoMoO4/CFs remained 84%,which was an increase of nearly 9 percentage points relative to PPy@CFs.So,we conclude that the introduction of CoMoO4 can improve the stability of ternary flexible electrode materials.Based on the characteristics of high cobalt ion activity and large specific surface area of the transition metal compounds with lamellar structure,we selected NH4CoPO4 as the intermediate carrier to construct PPy@NH4CoPO4/CFs flexible composite electrode materials in this chapter,and the ammonium source and solvent for synthesizing NH4CoPO4 were taken as variables to explore the influence of the variables on the conductivity and electrochemical performance through the control variable method.The results of two experiments showed that when water and polyethylene glycol were used as solvents,NH4Cl and(NH4)3PO4 were used as ammonium sources,the prepared PPy@NH4CoPO4/CFs flexible composite electrode material had the best electrical conductivity and electrochemical performance.The specific capacitance was 551.6 F/g at a current density of 0.2 A/g,which was 2.1 times that of PPy@CFs.In order to further evaluate the electrochemical performance of PPy@NH4CoPO4/CFs flexible composite electrode materials,we conducted a cycle stability test analysis on the above mentioned PPy@NH4CoPO4/CFs with the best performance and the blank PPy@CFs.The experimental results showed that after 1000 charge-discharge cycles at a current density of 3 A/g,the initial specific capacitance of PPy@NH4CoPO4/CFs remained 87%,which was an increase of nearly 12 percentage points relative to PPy@CFs.Compared with PPy@CoMoO4/CFs flexible composite electrode material,the specific capacitance of their is nearly,but the stability of PPy@NH4CoPO4/CFs is better,which benefits from the lamellar structure of NH4CoPO4.