Design And Synthesis Of New Quinone-based Flexible Composites And Their Energy Storage Research

Flexible supercapacitors have a broad application prospect due to their high-power density,long cycle life,good mechanical properties and high security.Among them,the development of high-performance flexible electrode materials is a hot research topic in this field.Poly（1,5-diaminoanthraquinone）（PDAAQ）,a new conductive polymer,is considered as a promising electrode material due to its uniqueπ-conjugated structure,excellent cycling stability and high theoretical capacity.In this thesis,a series of polymer-based flexible composite electrode materials with high energy storage capacity and outstanding stability were finally prepared by growing polyaminoanthraquinone materials with high pseudocapacitive energy storage activity on the surface of flexible conductive carbon cloth（CC）as the substrate through different experimental strategies.The main study is divided into the following three parts:（1）In this work,the controlled polymerization of aminoanthraquinone molecules and the final polyaminoanthraquinone/carbon cloth（PDAAQ/CC）flexible composite electrode material were achieved by chemical oxidation method using flexible carbon cloth as the substrate.In the PDAAQ/CC composite electrode,thanks to the good synergy effect between the energy storage active material（PDAAQ）and the flexible conductive substrate（carbon cloth）,the energy storage capacity of the PDAAQ/CC flexible composite electrode is increased by about 100%compared to the pure PDAAQ material.Electrochemical experiments revealed that the PDAAQ/CC flexible electrode has a specific capacity of 423m F cm^-2at a currentdensity of 1 m A cm^-2(approximately 226 m F cm^-2for polyaminoanthraquinone electrode material).After 10,000 cycles,the capacitance retention of this flexible electrode was about 78.9%.The kinetic analysis showed that the energy storage behavior of the PDAAQ/CC flexible composite electrode was dominated by the capacitive process(about 61.7%capacitance contribution at 30 m V s^-1).（2）In this work,we accomplished the in situ-controlled growth of polyaminoanthraquinone material on the flexible carbon cloth substrate by means of electrochemical polymerization（EP）and prepared a flexible electrode material of polyaminoanthraquinone/carbon cloth（EP-PDAAQ/CC）.The polymer PDAAQ was observed by scanning electron microscopy to achieve a uniform distribution on the carbon cloth with a nano-protruding structure.Meanwhile,this thesis systematically investigates the effects of monomer concentration,polymerization voltage,supporting electrolyte types and charge density on the energy storage performance of EP-PDAAQ/CC flexible electrodes.The optimal preparation conditions are:10 m M aminoanthraquinone monomer,0.1 M tetraethylamine tetrafluoroborate and 0.5 M trifluoroacetic acid in acetonitrile solution,polymerization voltage of 1.2 V and charge density of 12 C cm^-2.The flexible electrodes obtained under optimal preparation conditions have excellent energy storage capacity(specific capacitance of 645 m F cm^-2at 1 m A cm^-2and 83.5%of the initial capacity after10,000 cycles at a current density of 3 m A cm^-2).The kinetic analysis showed that the capacitance contribution was as high as 78.1%at a scan rate of 100 m V s^-1,exhibiting fast electrochemical kinetic properties.To test its practical application,we assembled symmetrical supercapacitors with EP-PDAAQ/CC flexible electrodes.The specific capacitance of the device reached 102 m F cm^-2at 1 m A cm^-2.Meanwhile,the energy density of the symmetric supercapacitor reaches 5.2μWh cm^-2when the power density is 307μW cm^-2.（3）In this work,P（DAAQ-co-PDA）/CC flexible copolymer electrode materials were prepared on flexible carbon cloth substrate by electrochemical copolymerization method using 1,5-diaminoanthraquinone（DAAQ）and para-phenylenediamine（PDA）as monomers.It was observed by SEM that the prepared P（DAAQ-co-PDA）copolymer was uniformly covered with carbon fibers in carbon cloth.In order to confirm the optimal electrochemical copolymerization conditions for P（DAAQ-co-PDA）/CC flexible materials,the effect of monomer concentration ratio（PDA:DAAQ=1:5）and deposition time on the performance of P（DAAQ-co-PDA）/CC flexible materials was systematically investigated in this thesis.Electrochemical tests showed that the prepared P（DAAQ-co-PDA）/CC flexible electrode reached a capacitance of 700 m F cm^-2at the current density of 1 m A cm^-2,while the specific capacitance still reached 545 m F cm^-2at a 10-fold increase in current density(10 m A cm^-2).After a long cycle stability test（10,000 cycles）,the P（DAAQ-co-PDA）/CC flexible polymer material still achieves a capacity retention rate of 87.6%,which is higher than EP-PDAAQ/CC（83.5%）and PDAAQ/CC（78.9%）.We assembled the prepared P（DAAQ-co-PDA）/CC flexible material with symmetric supercapacitors,which exhibited excellent energy storage performance(specific capacitance of 146 m F cm^-2at 1 m A cm^-2).An energy density of 12.97μWh cm^-2was obtained at a power density of 413μW cm^-2.