Preparation And Properties Of Conductive Polymer/Cellulose Fiber Composites For Flexible Electrode Materials

Energy and environmental issues have existed for decades and will continue to be into the future.It is a challenge to store energy in an efficient and environmental friendly way.Moreover,the progress of flexible electronics requests new high efficient and sustainable materials for energy storage devices.Among numerous candidates,the green biomass resources are increasing explored to fabricate energy storage devices.As the largest biomass resource in the world,cellulose is not only cheap,widely available and renewable,but also unique in structure and easy to functionalization,which meets the requirements of sustainable energy storage.Conductive polymer is one kind of organic polymers with unique structures that has the advantages of cheap,readily available and environmentally friendly.As pseudocapacitance material,conductive polymers have received more attention in recent years due to their excellent electric and electrochemical performance.In this study,we focus on the applications of cellulose fibers(CFs)in energy storage area.Cellulose and conductive polymers(CP)were performed as substrate and electrochemical active material,respectively,to fabricate high performance electrode materials of supercapacitor.Aiming at the problems of current conductive polymer/cellulose fiber composites(CP/CFs)used as energy storage materials,such as low mass loading of active materials,poor conductivity and low specific capacitance,new methods and mechanisms have been created.The accomplishments have been summarized as follows:1.CFs were firstly modified with zirconium oxyhydroxide(ZrO(OH)2)to enhance the binding of phytic acid doped polyaniline(PANI:PA)to the surface.A compact coating of PANI:PA was developed on ZrO(OH)2/CFs through the chelating of zirconium ions to phytic acid.Doping PA into PANI coupled with deposition ZrO(OH)2 onto cellulose fibers was found as an efficient strategy to the deposition of PANI on CFs.It is proved that the modification of CFs and the doping of PA improved the electrical conductivity,flame retardancy and electrochemical stability of the composite material.2.CFs were first in situ modified with zirconium phenylphosphonate(ZrPP)to fabricate ZrPP/CFs.The as prepared ZrPP/CFs was used as substrate for the polymerization of PANI.The deposition behavior of polyaniline on CFs before and after modification was compared.The results show that ZrPP was uniformly attached to the surface of CFs to improve the binding of aniline monomer by π-π interaction between benzene rings.The maximum utilization rate of aniline monomer was about twice that of the control sample.In addition,PANI/ZrPP/CFs composites also exhibit excellent flame retardancy and electrochemical energy storage performance.3.New doping strategy was designed to prepare highly conductive poly(3,4-ethylene dioxyethiophene)/cellulose fibers composite(PEDOT/CFs)based on our previous studies.In order to improve the performance of PEDOT/CFs,novel combined small-sized anion doping agents,sulphosalicylic acid(SSA)and sodium benzenesulfonate(SBS),were adopted to construct a well-organized conducting layer.In particular,the PEDOT layer was uniformly coated onto the surface of CFs through dopant-dependent interface.Through the doping of SSA,PEDOT deposits evenly on the surface of CFs.As a surfactant,SBS not only improves the dispersibility of EDOT monomer,but also improves the doping level of PEDOT.The resulting PEDOT has good crystallinity and high doping level,and the highest conductivity can reach 471.7 S/m,and has excellent electrochemical stability,thermal stability,hydrophilicity and flexibility.4.Novel high performance PEDOT paper-based electrode was successfully developed by a simple post-treated process with plant-derived redox active ARS.The as-fabricated PEDOT-A paper electrode exhibited improved capacitance compared to the pristine PEDOT paper electrode.The redox active ARS was firstly introduced into the electrolyte to further improve the electrochemical performance of the paper electrode.Paper-based symmetric supercapacitors were successfully assembled using PEDOT-A paper electrodes and redox electrolytes.The results show that the addition of redox active molecule ARS can significantly improve the specific capacitance and energy density of PEDOT paper-based electrode materials,and is a new high-performance paper-based capacitor.5.High performance hybrid electrode materials was fabricated by simple mix-vacuum filtration process with former prepared PANI/ZrPP/CFs and PEDOT:SSA-SBS/CFs.The effects of different mixing ratios on electrochemical properties of flexible electrode materials were studied.The results show that PANI/ZrPP/CFs is mainly responsible for the contribution capacitance,while PEDOT:SSA-SBS/CFs is mainly responsible for providing the electronic transmission channel in the hybrid paper-based electrode materials.The specific capacitance of the hybrid electrode material can reach up to 588 F/g,which is much higher than pure PANI/ZrPP/CFs and PEDOT:SSA-SBS/CFs electrode materials.The hypothesis of preparation of high performance paper-based electrode materials by combination of PANI/ZrPP/CFs and PEDOT:SSA-SBS/CFs is proved.