Preparation And Capacitive Performance Of PEDOT:PSS-based Composite Fibers

With the continuous development of today’s flexible electronic products,fiber-shaped supercapacitors have attracted continuous attention.That’s due to their advantages such as light weight,controllable volume,good bending and tensile properties,and weavable.Fiber-shaped supercapacitors,with their unique one-dimensional fiber structure,can be combined with various other energy harvesting and conversion device devices into multifunctional integrated fiber-shaped electronic devices,which have huge application prospects in the field of wearable electronic textiles.Compared to graphene and carbon tubes,which are currently used to prepare highly conductive fibers,poly（3,4-ethylenedioxythiophene）:poly（styrenesulfonic acid）（PEDOT:PSS）have attracted extensive attention due to its superior cycling stability,better flexibility,and higher elongation at brea.1D confined self-assembly is an effective technique for the preparation of the highly-conductive PEDOT:PSS fibers.However,based on current reports,the conductivity and capacitance of PEDOT:PSS gel fibers prepared by self-assembly methods are relatively low,which greatly limits its application in the wearable field.There are two main factors that limit the conductivity and capacitance of PEDOT:PSS:excessive non-conductive PSS and PEDOT has a lower theoretical specific capacitance.Based on this,we prepare PEDOT:PSS-based fiber supercapacitors with flexible high conductivity and high capacitance by combining with PEDOT:PSS fiber with high capacitance performance and electrode materials（reduced graphene oxide and polyaniline）.In this thesis,the flexible and highly conductive PEDOT:PSS-based fiber is prepared by the hydrothermal self-assembly method combined with a series of optimization methods,and the application potential of it in the field of wearable energy storage is systematically explored.1.In the first part,we prepared binding-free PEDOT:PSS fibers（PFs）with high capacitive performance as electrodes for supercapacitors via a facile method followed by various solvent treatments.Dimethyl sulfoxide（DMSO）-treated electrodes displayed a superior specific capacitance（C_s）of 202 F g^-1 at the current density of 0.5A g^-1 with higher elongation at break,flexibility and conductivity of 140.7 S cm^-1,compared to those of pristine PEDOT:PSS electrodes.More importantly,the DMSO-treated fibers possessed improved stability,which retained 105%of the initial C_s after22,000 long cycles at 10 A g^-1.2.In the second part,we prepare a PEDOT:PSS/r GO fiber（PGF）with high-quality electrodes for supercapacitors by easily-accessible hydrothermal confinement reaction.The optimized P₃G₇F exhibits improved electrochemical performance including a high specific capacitance（C_s）of 249.5 F g^-1 at 0.5 A g^-1 and good cycling stability.Moreover,after introducing the PEDOT:PSS,the elongation at break of the P₃G₇F is doubled to 13.9%.A symmetric supercapacitor（SSC）based on the P₃G₇F displays a high specific energy density of 10.68 Wh kg^-1 at a specific power density of81.25 W kg^-1.The improved performance of the fabricated composite fiber is attributed to the unique structures of the r GO and PEDOT:PSS and their synergistic effect.This study introduces an opportunity for the development of next-generation flexible and wearable devices.3.In the last part,the poly（3,4-ethylenedioxythiophene）:poly（styrenesulfonic acid）/polyaniline（PEDOT:PSS/PANi）fiber has been prepared via an accessible technique of one dimensional（1D）self-assembly.Nevertheless,PSS as the main crosslinking matrix may lead to more hopping sites for charge carriers,lessening the continuous electrically-conductive path.Herein,PEDOT:PSS/PANi fiber was treated with dimethyl sulfoxide（DMSO）to remove the insulative PSS chains.Coupling high electroactivity of PANi and high conductivity of PEDOT,the optimized DMSO-PEDOT:PSS/PANi fiber displays enhanced electrochemical properties with a high specific capacitance（C_s）of 367.7 F g^-1 at 0.5 A g^-1 and good rate capability.Moreover,a symmetric FSC based on the DMSO-P₄P₆ fiber exhibits a high energy density of 42.4Wh kg^-1 at a power density of 302.3 W kg^-1.