Structural Regulation And Electrochemical Properties Of PAN-based Felxibile Carbon Nanofiber Electrodes

With the birth and development of flexible wearable electronic products,the development of flexible supercapacitors with high ratio capacity has become an important research focus in the field of energy storage.At present,the main problem which restricting flexible supercapacitors used in real life is the low specific capacity,especially the introduction of flexibility to supercapators further reduces its specific capacitance.Therefore,the development of supercapacitor electrode materials with both flexibility and high specific capacitance is the key factor to promote the further development of flexible wearable devices.Polyacrylonitrile?PAN?based carbon nanofibers?CNF?prepared by electrospinning with the advantages of high conductivity,good flexibility,low cost and large-scale preparation,is of great potential to work as a kind of flexible supercapacitor electrode material.However,the specific surface area of CNF produced by electrospun PAN nanofibers is so small,and the pore structure?micro-meso-macro porous?needs to be optimized,resulting in the performance of its supercapacitor far below the application requirements.In view of the existing problems of PAN-based carbon fiber,this work designed to modify the pore structure and specific surface area of PAN-based fiber by releasing a large amount of heat and gas during thermal decomposition of energetic materials.At the same time,the carbon nanofibers can be"welded"by the heat release properties of the energetic materials to realize the crosslinked carbon nanofibers.Compared to the CNF without modified,the CNF contained energetic materials can significantly increase the specific surface area of carbon nanofibers,optimize the pore structure and crosslinked fiber characteristics,so as to improve the specific capacity and rate performance of carbon nanofibers.1.The study on the structure of flexible electrospun CNF electrode modified by nitrocellulose?NC?The PAN/NC composite fiber was prepared by using electrospinning technology,in the subsequent carbonization process,the decomposition of NC produces a lot of heat and gas,which can modify the structure of CNFs.Electrochemical performances of different CNFs were carried out in a standard three-electrode system,the CNF-5 possesses a high specific capacity of 192.9 F/g?20 m V/s?,much higher than the specific capacity of PCNF electrodes?103.16F/g?.In addition,the as-prepared electrode has excellent cycling stability and rate capability.2.The study on the structure of flexible electrospun CNF electrode modified by Na N₃.The Na N₃/PAN composite fiber mat was prepared by electrospinning technology,the influence of the content of NaN₃ in composite fibers and carbonization temperature on fiber structure and electrochemical performance were investigated.Crosslinked carbon nanofiber films with hierarchical pores as flexible electrodes were prepared successfully,and the CNF-5-900 electrode shows the better electrochemical performance:a high specific capacity as high as222.92 F/g,excellent rate capacity?the capacity retention is 81.97%?,longer cycle life and outstanding mechanical properties.3.A wire-shaped composite carbon fiber electrode was prepared by solvent and non-solvent method.In this paper,a solvent and nonsolvent method combining with carbonization process were used to prepare the wire-shaped PAN/GO/SWCNT fibers.The amorphous carbon structure of electrode is derived from the carbonization of PAN,reduced graphene oxide and single-walled carbon nanotubes during carbonization process.And the addition of GO and SWCNT can increase more pores,high specific capacity and mechanical property of electrode materials.In the three electrode testing system,the wired-shaped electeode can achieve a high specific capacitance of 129.59 m F/cm²,and shows the excellent cycle stability?approximately 99.51%?.