Research On Carbon Black Doped Nano-carbon Fiber And Its Capacitance Performance

Supercapacitor,as a new environmentally friendly energy storage device,has been widely employed in many fields.Electrode materials are the core of supercapacitors,determining the performance of the supercapacitors.Porous carbon materials are widely used as electrode materials for supercapacitors due to their high specific surface area,good chemical stability,high conductivity and low cost.Porous carbon materials used for capacitors include activated carbon,carbon aerogel,graphene,carbon nanotubes(CNTs)and carbon nanofibers(CNFs).Over the past decade,electrospun carbon nanofibers(ECNFs)have attracted much attention due to their nano-scale,self-supporting structure and simple preparation process.In order to improve the capacitive performance of electrospun carbon nanofibers,researchers focused on improving the porosity and specific surface area.In various attempts,introducing templates and adding post activation are commonly used,but they generally have the problem of cumbersome process.In order to simplify the process,porous nanocarbons were directly introduced in the spinning solution.Porous carbon black(CB)with zero-dimensional properties was introduced to spinning aids.Porous carbon nanofibers were prepared by electrospinning,preoxidation and carbonization.The main results are as follows:(1)The modified carbon black(MCB)was introduced to PVP/ethanol spinning solution and porous carbon nanofiber webs were prepared by electrospinning,preoxidation and one-step carbonization.The MCB addition amount was adjusted and the maximum mass ratio of MCB/PVP reached 1.5:1.The MCB-based carbon nanofibers(MCNFs)were mainly composed of micropores and small mesopores.When the addition ratio of MCB/PVP was 1.5:1,the MCNFs showed specific surface area of 624 m2·g-1,high carbon yield of 54%,The MCNFs were directly cut into electrodes for supercapacitors,and the electrochemical performances of the MCNFs were evaluated in 6 M KOH in three-electrode configuration.The MCNFs showed a maximum specific capacitance of 166 F·g-1 and rate performance reaches 54%(from 0.1 to 10A·g-1).(2)The carbon black(CB)was introduced to PAN/DMAC/acetone spinning solution and porous carbon nanofiber webs were obtained directly by electrospinning,preoxidation and carbonization.The mass ratio of CB/PAN reached 0.75:1.With the increase of CB/PAN mass ratio,the thermal stability of as-spun fibers was improved and the specific surface area of final carbon nanofibers was increased gradually.The CCNF-0.75 showed maximum specific surface area of 478.2 m2·g-1,With the increase of carbon black content,the carbon yield increases,up to 60%.At the same time,carbon black doping significantly improves the conductivity of CCNFs.The resistivity of CCNF-0.75 is only 0.24 Ω·cm.CCNFs have a hierarchical pore structure similar to CB.The CCNFs were directly cut into electrodes,and the electrochemical performances of the CCNFs were tested in a three-electrode system.CCNF-0.75 showed the best electrochemical performance.The specific capacitance value is 174.7 F·g-1 at the current density of 0.1 A·g-1.