Preparation Of Phenolic-based Porous Nano-carbon Fiber By Electrospinning And Its Electrochemical Properties

Supercapacitor,as a kind of energy storage device with high power density and energy density,has attracted wide attention of researchers.As the core of the supercapacitor,the electrode material determines the electrochemical performance of the supercapacitor.In order to develop the electrode material with excellent performance,the phenolic resin-based porous carbon nanofibers were prepared.The electrochemical properties of phenolic resin-based porous carbon nanofibers as electrode materials are also investigated.The specific research content and results are as follows:(1)The ribbon-like porous carbon nanofibers with about 80%mesoporous are prepared by electrospinning,curing,carbonization and pickling processes,in which low molecular weight resol phenolic resin is used as carbon precursor,ethanol as solvent,PVP as spinning aid and Co(NO3)2 as template.The results show that the specific surface area and total pore volume obviously increase with the increase of Co(NO3)2 added proportion.However,when the mass ratio of Co(NO3)2 and phenolic resin was further increased,the spinning process was difficult to continue.Therefore,there is an optimum proportion between precursor and Co(NO3)2 for spinning solution.In the optimum condition,the flattened morphology of porous carbon nanofibers remains intact and the specific surface area and total pore volume were 463 m2/g and 0.575 cm3/g.The narrow pore size distribution from 3.5 to 4.5 nm is achieved.The discharge specific capacity of the porous carbon fiber materials reaches 223 F/g(0.2A/g)in 6 M KOH electrolyte.(2)The introduction of Co(NO3)2 as a template agent makes mainly mesoporous,meanwhile the specific surface area is low,so the preparation of micropore-mesopore-macropore hierarchical porous carbon nanofibers can increase the specific surface area and improve the pore structure.In the research,Mg(NO3)2,decomposed to MgO particles,is used to replace cobalt nitrate to prepare the porous carbon nanofibers with hierarchical pore structure.All the samples can maintain the flattened morphology of fibers and the pore structure shows a multi-level distribution.In the optimal condition,the specific surface area and total pore volume of the sample reached 779 m2/g and 0.844 cm3/g,respectively.The pore size distribution broadens to 0.4-60 nm and the highest capacitance is of retention of 72%.(3)Graphite structure of carbon materials can improve the electronic conductivity and porous carbon material is conducive to the transport of electrolytic ions,so the preparation of the higher graphitization porous carbon fiber as the electrode material is necessary.In this study,nano-MgO with certain catalytic graphitization is used as template agent and activated by KOH in the later stage.The hierarchical porous carbon nanofibers with higher graphitization,high specific surface area(1058.4 m2/g)and pore volume(1.64 cm3/g)are obtained.