Preparation Of Conductive Polymers Blends With Redox Molecules As Electrodes For Electrochemical Energy Storage

Supercapacitors are a new type of electrical energy storage devices with high power density,limited doping level,fast charge and discharge speed and long cycle life.Current research challenges focus on the improvement of energy density,cycling stability,and mechanical properties.Conductive polymers have the advantages of low cost,high environmental stability,high charge storage capacity and wide potential window.At the same time,such materials have the problem as low actual specific capacity,poor rate performance and cycle stability.Based on this,we use quinone molecules and covalent organic frameworks（COFs）materials doped with conductive polymers to improve the energy storage capacity.The specific research contents are as follows:（1）We adopted nitrogen-doped carbon nanotubes（N-CNTs）deposited carbon cloth as the conductive substrate（CC@N-CNTs）to provide electron transport and ion diffusion channels for conductive polymers.Moreover,the modification of nitrogen atoms in carbon skeleton can significantly change the surface electron distribution and further improve the electronic conductivity.Then,in the presence of 3,4-ethylenedioxythiophene（EDOT）and sodium anthraquinone-2-sulfonate（AQS）,the AQS doped PEDOT was obtained by constant voltage electropolymerization（N-CNTs@AQS-PEDOT）.By optimizing the feeding molar ratio of monomer/dopant,N-CNTs@AQS-PEDOT shows a highest conductivity of 5635 S m^-1（the feed molar ratio is 2:1）.We employed AQS as the redox dopants and electrolyte additive,achieved stable faradic reactions in bulk CPs and on the interfaces between CPs and electrolyte,which tripled the specific capacity of the PEDOT electrode from 0.4 m Ah cm^-2(92.0 m Ah g^-1)to 1.3 m Ah cm^-2(293.3 m Ah g^-1).More importantly,the redox ion-layering dopant and electrolyte additive endows PEDOT electrode with robust cycling stability and 100%coulombic efficiency.After 10000 galvanostatic charge/discharge cycles,AQS doped PEDOT electrode shows a capacity retention of 82.4%and 173.5%in 1 M H₂SO₄electrolyte without or with 0.03 M AQS additive,respectively,which was higher than that of PEDOT electrode（70.0%,141.7%）,respectively.In an asymmetrical device assembled with active carbon as positive electrodes,the maximum volumetric energy density of 12.1 m Wh cm^-3 at a power density of 25.1 m W cm^-3.（2）The covalent organic framework（COFs）material was coated on the CC@N-CNTs substrate by the solid-phase synthesis method,and then the N-CNTs@COF@PANI electrode is synthesized by the constant voltage electropolymerization method.N-CNTs@COF@PANI achieves an area specific capacitance of 1133 m F cm^-2 at the current density of 1 m A cm^-2.The electrochemical performance was greatly improved compared with the N-CNTs@PANI electrode(512m F cm^-2)and the N-CNTs@COF electrode(36 m F cm^-2),indicating that the COFs and the PANI play a synergistic role in promoting the electrochemical energy storage performance.The capacitance retention was 81.1%and the coulombic efficiency stabilizes at 100%after 10000 cycles at a current density of 20 m A cm^-2.