Preparation Of Silk Fabric-based Electrode And Its Assembly In Supercapacitor

With the rapid development of a variety of electronic devices such as roll-up displays,smart mobile devices and implantable biosensors,the miniaturized,portable,lightweight and environmentally friendly energy storage devices have attracted extensive attention.Supercapacitors have been regarded as one of the most promising energy storage equipments owing to their high power density,fast charge-discharge rate and long cycle life.Commercial fabrics represent an interesting option to become a good electrode material for assembling supercapacitors,owing to their inherent softness,high porosity and excellent mechanical strength.In this study,based on the silk fabrics,the self-supporting high-capacitance fabric electrode materials were prepared by dyeing technique,carbonization and coating of polypyrrole(PPy)and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS).All-solid supercapacitors were assembled by the silk fabric-based electrodes.The detailed work is summarized as follows:(1)Since the dye molecules contain heteroatoms such as oxygen,sulfur and nitrogen,these heteroatoms can be uniformly doped into the fabric structure to enhance the capacitance properties of the carbon electrode material through a dyeing procedure.In this study,free-standing carbon electrodes were obtained through treating the silk fabrics with two different acid dyes followed by carbonization.The results showed that when dyeing with acid dye,the heteroatom contents of carbon electrode increased from 14.40%to 20.01%.At the scan rate of 2mV/s,CSF-R showed a capacitance of 255.95F/g and the operation voltage window can be expanded to 1.4V.When dyeing with acid media dye,the heteroatom contents increased from 13.81%to 31.58%,the specific capacitance of CSF-B reached 305.02F/g.In addition,the capacitance retention with only 10%capacitance loss after 5000charge-discharge cycles,indicating good cycling life stability of the two electrodes.(2)Based on the high conductivity of carbonized silk fabrics,polypyrrole/carbonized silk fabric composite electrode was obtained by electrochemically depositing a high PPy mass loading on the carbonized silk fabric.The results showed that under the optimized conditions(molar ratio of n(Py)to n(TsOH)was 1:2 and deposition time of 2300s),the obtained PPy/CSF-2300 composite electrode showed a large PPy mass loading with 16.02mg/cm~2 and a low square resistance(2.11±0.04?/sq).Furthermore,the PPy/CSF-2300 electrode displayed an excellent areal capacitance of 4040mF/cm~2 at 2mA/cm~2 and capacitance retention rate of 88.6% after 1500 charge and discharge cycles.The solid supercapacitor assembled with two electrodes also possessed high energy density of 6.88mWh/cm~3,which is superior to the related PPy-based supercapacitors.(3)A conductive fabric-substrate can be obtained through using a silk fabric as the substrate via adding MWCNT and drop-coating PEDOT:PSS method.Then a high electrochemical performance electrode can be obtained by electrochemically depositing PPy on the substrate.The results showed that under the optimized condition with ten times drop-coating processes,the obtained PEDOT:PSS@MWCNT/SF exhibited outstanding conductivity with sheet resistance of 6.86±0.75?/sq.After loading of PPy,PPy/PEDOT:PSS@MWCNT/SF composite electrode showed a low square resistance of 1.57±0.11?/sq and a high areal capacitance of 5296mF/cm~2 at 2mA/cm~2.In addition,the PPy electrode possessed a good electrochemical stability with capacitance retention of 94.3%after 5000 cycles.Supercapacitor assembled with the two electrodes displayed high energy density of 1.87mWh/cm~3.