| With the rapid development of flexible wearable devices,flexible supercapacitors have become one of the hot spots of energy storage.The preparation of high performance flexible electrodes is still the bottleneck restricting the development of flexible solid-state supercapacitors.At present,PPy/CC composite flexible electrodes in the production process,or need to use adhesives or preparation methods complex,high cost or low performance,resulting in difficult to scale,in contrast to the gas phase polymerization method is cheap,simple and electrode has good flexibility.However,traditionally gas phase polymerization is usually a single gas phase pyrrole monomer.There are few reports about the influence of gas phase polymerization environment on the performance and structure of the prepared PPy/CC composite electrode.Meanwhile,the prepared polypyrrole has low conductivity and insufficient energy storage performance of the electrode.Therefore,this paper optimizes the morphology and structure of polypyrrole grown in situ on the surface of carbon cloth by regulating the gas phase polymerization environment of pyrrole,in order to obtain a flexible electrode with high electrochemical performance.The effects of pyrrole monomer volume,oxidant concentration,polymerization temperature and polymerization time on the electrochemical performance of the composite electrode in the presence of water vapor were investigated.Furthermore,small organic molecules were introduced into the gas phase polymerization environment of pyrrole,and the effects of different small organic molecules on the morphology,structure and electrochemical performance of polypyrrole grown in situ on the surface of carbon cloth were investigated.On this basis,a three-dimensional porous hydrogel network structure was introduced to improve the load of polypyrrole and increase the electrochemical active area of the electrode active substance.A composite integrated PPy/CC composite flexible electrode with high area specific volume was obtained,and the assembled flexible all-solid supercapacitor showed good energy storage performance.It provides a new idea for the energy supply system design of flexible wearable devices.The main research results are as follows:（1）PPy/CC composite electrode was prepared by controlling the evaporation volume of pyrrole monomer and aqueous solution by using carbon cloth as flexible substrate and ferric chloride as oxidant.The morphology and structure were analyzed by scanning electron microscope,Fourier infrared and Raman spectroscopy.Its electrochemical performance was analyzed by cyclic voltammetry characteristic curve,constant current charge-discharge and impedance spectrum.Studies have shown that the distribution of polypyrrole becomes more uniform and ordered when a small amount of water is introduced into the polymerization environment.With the increase of water molecule content,the particle size of polypyrrole decreased,and the polypyrrole prepared when the evaporation volume of water and pyrrole monomer solution was 10:1 showed uniform distribution of nanospheres.The effects of oxidizer concentration,polymerization temperature and polymerization time on the morphology,structure and energy storage performance of polypyrrole/carbon cloth composite electrode were further studied.The results showed that:When oxidizer concentration is 2.0 M,polymerization temperature is 60℃and polymerization time is 90min,the prepared polypyrrole/carbon cloth composite electrode has the highest energy storage performance.When current density is 5 m A cm-2,the area specific capacitance is 1140.7 m F cm-2.（2）The vapors of different types of small organic molecules（methanol,ethanol,benzyl alcohol,toluene and acetonitrile）were introduced into the gas phase polymerization environment.Under the optimized conditions of（1）,the gas phase polymerization time was controlled to be 90 min,the polymerization temperature was 60℃,and the oxidant concentration was 2.0 M.At the same time,the organic solvent was:water:The polypyrrole/carbon cloth composite electrodes were prepared with the volume ratios of 1:10:1 and 3:10:1,respectively.The effects of different types of organic small molecule solutions and their evaporative volume ratio on the overall performance of the electrode were investigated.Scanning electron microscopy（SEM）test showed that the morphology of polypyrrole prepared by different organic small molecules participating in gas phase polymerization had certain differences,among which ethanol was spherical composed of granular polypyrrole,toluene was trumpet shaped,and the distribution was uniform.When ethanol is added as a small molecule and the volume of ethanol:water:pyrrole monomer solution is 1:10:3,the electrode prepared has the largest conjugate chain length,and the electrochemical energy storage performance is the best.When the current density is 5 m A cm-2,the area ratio capacitance of 1413.7m F cm-2 is 1413.7 mf cm-2.The flexible symmetric all solid state supercapacitor has an area specific capacitance of 470.3 m F cm-2 when the current density is 5 m A cm-2.After 3000 times of charge and discharge,there is still 98.7%capacitance retention rate,with good cycle stability.When the area power density is 2500μW cm-2,the maximum area energy density is 65.3μWh cm-2.（3）PPy/CC composite gel electrode was prepared based on the gas-phase polymerized water environment.Polyvinyl alcohol porous gel was introduced to increase the specific surface area of the electrode,and carbon nanotubes with a mass fraction of 5 wt.%were added to improve the conductivity of the electrode.The effect of polymerization temperature on the preparation of PPy/CC composite gel electrode was further studied.The morphology and structure of PPy/CC composite gel electrode were analyzed by scanning electron microscopy,Fourier infrared and Raman spectroscopy as well as X-ray diffraction pattern.The electrochemical performance of polypyrrole composite gel electrode was analyzed by cyclic voltammetry characteristic curve,constant current charge-discharge and impedance spectroscopy.Studies show that with the increase of polymerization temperature,the energy storage performance of PPy/CC composite gel electrode first increases and then decreases.When the polymerization time is 90 min and the polymerization temperature is 60℃,the prepared PPy/CC composite gel electrode shows the maximum energy storage performance:When the current density is 5 m A cm-2,the specific capacitance is 4007.3 m F cm-2.When the current density is 5 m A cm-2,the flexible symmetric supercapacitor has a specific capacitance of 1080.0 m F cm-2,and the flexible supercapacitor has a small internal resistance（4.5Ω）.After 2000 continuous charge and discharge cycles,the initial specific capacitance retention rate of the device is about 89.5%,and when the area power density is 2700μW cm-2,the maximum area energy density of the device is 150μWh cm-2,showing excellent energy storage characteristics,and has broad development prospects in the future wearable field. |
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