Preparation And Electrochemical Properties Of Electrospun Carbon Nanofibers Composites

As a new type of energy storage device,supercapacitor has the advantages of high power density,short charging time,long service life,good temperature characteristics,and environmental protection.The refore,it shows strong market potential.The difficulty in researching supercapacitors is finding high-performance electrode materials.With the continuous development of science and technology,new nano-carbon materials such as carbon nanotubes and carbon fibers have widely been used in high performance electrode materials due to all the superb characteristics.There are many methods for preparing nano-carbon materials,and the electrospinning method is favored by virtues of simple equipment,convenient operation,low cost,and continuous preparation.within this context,different carbon nanofiber materials are prepared by electrospinning and other auxiliary methods.The microstructure and physical properties of the prepared carbon nanofiber composites were characterized by TEM,SEM,BET and XPS.The formation mechanism and microscopic composition are studied;the electrochemical performance of the composites is tested by electrochemical workstation,and the relationship among the electrical properties of the materials and the microstructure and composition of the materials is analyzed.The details are as follows:(1)Using the strong oxidizing property of concentrated sulfuric acid and hydrogen peroxide,the biomass-based cannabis straw is treated to obtain oxidized biomass carbon.The spinning solution was mixed with polyacrylonitrile,and the biomass-based activated carbon nanofiber composite is successfully prepared by electrospinning and KOH high temperature activation.Aft er a series of microscopic characterization,we found that the prepared biomass-based activated carbon nanofibers have high carbon yield and no impurities;the diameter is about 180nm;the specific surface area is 2348.73cm²·g^-1,and the pore size distribution is about 1.9nm.As an electrode material,its specific capacitance is as high as 261.2 F·g^-1at a current density of 1A·g^-1,and the specific capacitance can still reach 219 F·g^-1 at a high electrode density of 10A·g^-1,and the capacitance retention rate is 83.8%.In addition,at a current density of 2A·g^-1,after 3000 charge/discharge cycles,the capacitance loss is only 4%.(2)Using polyethylene glycol as pore-forming agent,polyphosphoric acid as phosphorus source and PAN as carbon source,phosphorus-doped porous carbon nanofibers with excellent capacitance properties were successfully prepared by electrospinning and high-temperature carbonization.Through microstructural characterization,we found that in order to reduce the fusion merger phenomenon of the fiber,the phosphorus incorporation is controlled at 1.0g,and the phosphorus content in the carbon fiber prepared under this condition reaches 0.37%.When the prepared carbon nanofiber material was fabricated into an electrode for electrochemical testing,it exhibites excellent capacitance performance.When the current density is 0.5A·g^-1,its specific capacitance is 228.7F·g^-1.When the current density increases to 10A·g^-1,its specific capacitance still reaches 84.37%of the initial value;And at 2A·g^-1At high current density,the capacitor has no attenuation after5000 cycles of charge and discharge.At the same time,in the water system electrolyte,the voltage range can reach 1.6V.(3)Co S₂/CNFs composite is prepared by electrospinning and hydrothermal synthesis with PAN as carbon source,thioacetamide as sulfur source and cobalt acetate as cobalt source.Co S₂ is successfully loaded onto the surface of CNFs.Through microscopic characterization and electrochemical performance testing,we explores the effects of hydrothermal reaction temperature and hydrotherma l reaction time on the product,and selected the optimum process conditions for the preparation of Co S₂/CNFs composites.Under the optimum process conditions,the prepared Co S₂/CNFs-2 composite material exhibits brillant electrochemical performance when used as a supercapacitor electrode material.When the current den sity is 1A·g^-1,the specific capacitance is 378F·g^-1.At the current density of 2A·g^-1,the capacitance retention rate reaches 89.5%after 1000 cycles of charge and discharge.