Study On Preparation And Capacitive Performance Of Paper Electrode Materials Via In Situ Generation Of Conductive Polymers

With the increasing depletion of fossil energy and the aggravation of new environmental problems,the research and development of new,environment-friendly and sustainable energy storage devices has attracted extensive attention.Although solar and wind energy are green,sustainable and environment-friendly,they also have some intermittence,uncertainty and other defects.Therefore,we need to seek new alternative energy devices.Among them,supercapacitor has been deeply studied because of its advantages,such as fast charge and discharge,high power density,long cycle life and wide operating temperature range.Especially in recent years,with the rapid development of wearable and portable devices,it also puts forward some higher requirements for the devices,such as excellent electrochemical performance,good flexibility,greenness,renewable,environment-friendliness and so on.Pulp fibers(PFs)have the characteristics of natural regeneration,environmental friendliness,intrinsic flexibility and good wettability.Conductive polymers(e.g.,PANI,PPy,and PEDOT)as active electrode materials have the characteristics of easy synthesis,low price and controllable electrochemical performance,which can meet the requirements of sustainable development in the field of energy.This paper focuses on solving the shortcomings of conductive polymers@pulp fibers paper electrode materials,such as poor specific capacitance and cyclic stability.In this paper,the modification of pulp fibers,doping of conductive polymers,and electrolyte additives were used to reconstruct the paper electrode materials,and their capacitive performance was studied.The PFs were modified by CoOOH in an open system at room temperature,and PPy@CoOOH@PFs paper electrode materials were prepared via in-situ polymerization.The results show that this method can make the loading of PPy on the surface of PFs more compact,which can improve the conductivity of the electrode materials.At the same time,it also help to reduce the volume expansion or collapse caused by ion insertion/removal of conductive polymers in the electrochemical process,suggesting the electrode materials have better specific capacitance and cyclic stability.The crystalline nano-sized ZIF-67-OOH with metal organic framework ZIF-67 as precursor was loaded on the surface of the pulp fibers in water and water/methanol phase,and the PPy@ZIF-67-OOH@PFs paper electrode materials were prepared via in-situ chemical oxidative polymerization.The PPy can be anchored by ZIF-67-OOH through Co-N chemical bonding force,which is obviously stronger than the intermolecular force between pulp fibers and PPy.Compared with PPy@PFs and PPy@CoOOH@PFs paper electrode materials,the PPy@ZIF-67-OOH@PFs paper electrodes have more excellent specific capacitance and cyclic stability.From the doping perspective of conductive polymers,AQS dopant was selected by investigating the doping effect of dye molecules with electrochemical activity on PPy.It shows that AQS can effectively improve the specific capacitance and cyclic stability of PPy@PFs paper electrode materials by introducing AQS into PPy molecular chain.In view of the advantages of AQS for PPy doping and the defect of its low electronic conductivity as an organic electrode material,we use PEDOT with better conductivity as the active material.On one hand,we investigate the doping effect of azo/anthraquinone dopants on PEDOT.On the other hand,we propose to use PEDOT to solve the problem of low electronic conductivity of this kind of electrochemical active dopants.There are synergistic action between dopants and PEDOT,which realizes the target of PEDOT:AQS@PFs paper electrode materials with higher specific capacitance.Compared with PEDOT@PFs paper electrode materials without AQS dopant,PEDOT:AQS@PFs paper electrode materials show a higher doping level.The PEDOT:AQS@PFs paper electrodes possess more excellent specific capacity and cyclic stability,which can be attributed to the doping effect of AQS.At the same time,it also proves the potential application of the electrode material in the field of electrochemical energy storage.The paper also studied from the two aspects of electrode material and electrolyte,AQS was added into H2SO4 solution to optimize the interface between electrode material and electrolyte,and it can realize inside and interfacial faradic reaction,which is conducive to further improve the capacitive performance of electrode material.The results show that the as prepared PEDOT:AQS@PFs paper electrode materials have higher specific capacitance in H2SO4/AQS composite electrolyte than that in H2SO4 electrolyte.This method provides a new idea for the research of CPs@PFs paper electrode materials and unlimited possibilities for their application in the field of electrochemistry.