Preparation Of PAN Nanofiber Yarn And Its Application In Supercapacitor

With the emergence of lightweight and flexible wearable electronics,the development of matching flexible energy storage devices has become a research priority.Yarn-like supercapacitors have received a lot of attention from researchers because of their advantages such as light weight,flexibility,easy preparation and easy weaving.In this paper,the advantages of electrostatic spinning and solution jet spinning are combined to design an electrostatic-solution blow spinning device,through which a variety of nanofiber yarns are prepared,and the spinning process of polyacrylonitrile（PAN）nanofiber yarns is explored and optimized.Nanofiber yarns containing different conductive nanoparticles were used as flexible substrates,and the yarn electrodes were prepared by in situ grafting polypyrrole,and the gel electrolyte was coated on the electrode surface to assemble a symmetrical supercapacitor to study the electrochemical properties of the electrode materials.The main research contents and results include.（1）An electrostatic-solution blowing device for continuous preparation of nanofiber yarns was constructed under the dual action of electrostatic field and airflow field,and the suitability of the device was verified by preparing various nanofiber yarns（NFYs）such as PAN and PAN/cotton core yarn.The effects of different solution concentration,voltage,air pressure,funnel speed and winding speed on the diameter of nanofibers and yarns were investigated.The results showed that the nanofiber diameter was uniform and well arranged with high yarn orientation when the PAN solution mass fraction was 11%,the voltage was 8 k V,the air pressure was 0.06 MPa,the funnel speed was 300 rmp,and the winding speed was 0.3 mm/s.The Box-Benhnken（BBD）response surface method was used to optimize the spinning parameters,and the regression model showed that the order of influence of each factor on the yarn diameter was:winding speed>electrostatic voltage>airflow>funnel speed,and there was an obvious interaction between the factors.（2）Conductive nanoparticles CNT and MXene were added into PAN spinning solution respectively,and PAN/CNT and PAN/MXene nanofiber yarns,namely NFY-PAN/CNT and NFY-PAN/MX,were prepared by electrostatic-solution blowing device,while pure PAN nanofiber yarns（NFY-PAN）were prepared for comparison.Conductive polymer polypyrrole（PPy）was deposited on the surface of the three yarns respectively to obtain NFY-PAN/CNT PPy,NFY-PAN/MXene PPy and NFY-PAN PPy electrode materials,which were assembled into yarn-like supercapacitors by surface coating with polyvinyl alcohol/lithium chloride/phosphoric acid（PVA/Li Cl/H₃PO₄）gel electrolyte.The results show that the optimal polymerization time is 3 h.The results of the three-electrode test indicate that the yarn electrodes have certain capacitance.Comparing the performance of the assembled supercapacitors,it was found that the electrochemical performance of NFY-PAN/MX PPY capacitors was better.The energy density and power density of the capacitor were 18.21μWh cm^-2 and 0.27 m W cm^-2,respectively,at a current density of 0.1 A g^-1,and the capacitance cycle retention rate was 65%after 5000 cycles.Finally,the NFY-PAN/MX PPy yarn-like supercapacitor was woven with common yarn to light up the LED lamp,confirming that the yarn-like supercapacitor can be used as an energy storage device to supply energy to flexible electronics.