Preparation And Capacitive Performance Research Of Functionalized PEDOT-based Composite Materials

In recent years,with the rapid development of portable,integrated and wearable electronic devices,the demand for micro-power supply is also increasing.As a reliable micro power supply,micro supercapacitors（MSCs）can be used in integrated circuits,passive electronic devices,micro sensors and other fields.It has the characteristics of fast charge/discharge,high power output,long cycle life and AC filtering.However,due to the lack of suitable electrode materials,there are still challenges in realizing the compatibility of micro-capacitors with high energy density,high power density and good mechanical properties in a limited area.Among the reported electrode materials,poly（3,4-ethylenedioxythiophene）:poly（styrenesulfonate）（PEDOT:PSS）has high conductivity,reversible electrochemical doping/de-doping ability,good environmental compatibility,and excellent flexibility,which can be used as an electrode material to construct highperformance MSCs.However,PEDOT:PSS,as an electrode material,has problems such as low capacity and poor response to high frequency signals,so it is challenging to achieve high capacity and good filtering performance.Because of PEDOT:PSS special molecular structure and electrical conductivity,on the functionalized modifications by chemical means,which is expected to achieve its capacitance performance improvements and special function.Based on this,by adjusting the molecular structure and composition of PEDOT:PSS,changing its morphology and surface interface properties,and combining carbon materials with good conductivity and transition metal sulfides with excellent pseudo-capacitance to improve the capacitance and adjust the rheological properties of the materials,we prepared PEDOT-based thin film electrode with excellent filtering performance and PEDOT-based printable ink with 3D printing function.At the same time,a series of different series-parallel micro-capacitors were constructed,and the capacitance and AC filter properties of the PEDOT-based electrode materials in MSCs were investigated.The main research contents are as follows:（1）the preparation of PEDOT@KB holey nanosheets（PKHNs）and its application in AC filter circuit.Ketjen black（KB）,which has high conductivity and high specific surface area（1461 m2 g-1）,was selected as composite modification material.PEDOT@KB composite hydrogel was synthesized by solvothermal method,and then the gel was treated by ultrasound to break its three-dimensional structure to form nanosheets with rich pore structure.The PKHNs were assembled into thin film electrodes by the filtration,and micro filter capacitors were further assembled.The properties of AC filtering are studied.With the help of the good conductivity of KB to reduce the interface resistance of PEDOT,while effectively avoiding the stacking of PEDOT nanosheets,adjusting the reaction parameters to construct the ordered pore structure of PEDOT nanosheets,accelerating the rapid diffusion of ions and efficient transport of electrons,with the help of the high specific surface area of two-dimensional materials,increase the charge storage sites,increase the capacitance of materials,and improve their responsiveness to high frequency current.The results show that the symmetrical supercapacitor based on PKHNs exhibits a phase angle of-81.7o,a resistance-capacitance time constant of 0.18 ms and an area specific capacitance of 3.02 m F cm^-2 at 120 Hz.In addition,micro capacitors based on PKHNs also show the successful conversion of AC signal to constant smooth DC signal output of single unit and series unit in AC lines,which reflects their great application in AC line filtering applications,and provides practical experience and theoretical guidance for the development of high performance micro filter capacitors.（2）A kind of PEDOT:PSS@WS₂ composite conductive ink suitable for 3D printing was developed,which can be used for the preparation of micro supercapacitors.The printing function of the composite is given by changing the composition,ratio and concentration of the composite ink and adjusting the rheological properties of the composite,such as apparent viscosity,storage modulus,loss modulus and so on.The extrusion 3D printing technology is used to prepare the micro electrode and further construct the micro capacitor to realize the adjustable electrode size at the micron level and capacitor pattern editing.With the help of material printing function,it can meet the practical application requirements of capacitors on various complex surfaces,and effectively improve the power and energy density of supercapacitors based on limited space area.MSCs based on PEDOT:PSS@WS₂ conductive ink has significantly enhanced electrochemical performance,high area specific capacitance(68.75 m F cm^-2),excellent energy density(12.7 μWh cm^-2)and power density(6 m W cm^-2),good cycle stability（capacitance retention of 86.4% after 9000 cycling）and excellent mechanical flexibility.The integrated micro capacitors assembled in series or parallel can meet the demand of target voltage or current output and can be used as micro power supply in different application scenarios such as micro robots,micro sensors,integrated circuits and so on.