| Coal tar pitch（CTP）is one of the excellent precursors for the preparation of carbon materials due to its low price,low ash content,high carbon content and easy graphitization.Carbon nanofiber non-woven fabrics with batch,continuous and diameter controllable could be prepared by electrospinning combined with oxidation and carbonization treatment.This non-woven fabric has the advantages of short ion transport channels,better structure self-sustainability and is a potential flexible electrode material.In this work,the flexible porous carbon nanofiber nonwovenn fabrics were successfully prepared by electrospinning,air oxidation and carbonization with acidified CTP as carbon source and polyacrylonitrile（PAN）or polyvinyl alcohol（PVA）as spinning aids.The pore structure of the non-woven fabric could be regulated by changing the type of spinning aids or the ratio of acidified CTP to spinning aids.The carbon fiber non-woven fabrics were used as the electrode of supercapacitor,and their electrochemical performance were investigated.The main contents and conclusions are showed as follows:（1）CTP was treated with mixed acid（H2SO4/HNO3）,and the effects of acid treatment on the chemical composition,pyrolysis behavior and group composition of CTP were studied.The results showed that after mixed acid treatment,the content of oxygen,nitrogen,sulfur and other groups in CTP increased,the light component gradually converted into heavy component,and CTP formed a more stable aromatic ring structure.In addition,after acid treatment,the polarity of coal tar pitch enhanced,and it is easier to dissolve in organic solvent,which is conducive to the preparation of uniform and stable spinning solution.The flexible coal pitch-based carbon nanofiber non-woven fabric was successfully prepared by electrospinning,air oxidation and carbonization treatment with mixture of acidified CTP,PAN and N,N-dimethylformamide（DMF）as spinning solution.（2）By regulating the mass ratio of acidized CTP to PAN in the spinning solution,Pitch-based carbon nanofiber non-woven fabrics with different structures were prepared by electrospinning,air oxidation and carbonization treatment.The as-prepared carbon nanofiber non-woven fabrics were used as supercapacitor electrode to investigate their electrochemical properties.The results showed that with the increase of the content of acidified CTP,the diameter of the fiber decreased,the conductivity increased,the specific surface area increased first and then decreased,and the pore size distribution range was widened,which effectively improved the capacity and rate performance of the carbon nanofiber non-woven fabrics.when the mass ratio of acidified CTP to PAN is 1/1.5,the specific capacity of the sample at 1 A g-1 is 186.6 F g-1;when the current density reaches to 50 A g-1,the concrete capacity of the sample can attain 66.7%.After assembling as a symmetric supercapacitor,the sample has 3.7 Wh kg-1 energy output at 22.8 Wh kg-1high power and 96.1%capacity retention after 10000 cycles,showing excellent cycle stability and reversibility.（3）Flexible porous carbon nanofiber non-woven fabric with abundant pore structure was prepared by electrospinning,air oxidation and carbonization treatment with mixture of acidified CTP,PVA,DMF and water as spinning solution.The results showed that compared with PAN/CTP-based carbon nanofiber,PVA/CTP-based carbon nanofiber has smaller diameter,higher conductivity and more developed pore structure and better electrochemical performance when used as supercapacitor electrode.The specific surface area of PVA/CTP-based carbon nanofiber is 788 m2 g-1,which is significantly higher than that of 495 m2 g-1 of PAN/CTP-based carbon nanofiber,and its specific capacity at 1 A g-1 current density is 265.8 F g-1.When the current density reaches to 50 A g-1,its concrete capacity is 213.2 F g-1,and its capacity retention rate can reach80.2%compared to 1 A g-1. |
