Preparation Of Multi - Layered Nanostructured Carbon Materials And Optimization Of Energy Storage Performance

In recent years, electrical energy storage with high energy density and power density attracted attention because of the depletion of fossil fuels. Supercapacitor, is considered as the most promising energy storage device with its high energy density, long-term operation stability and enviroumental friendly. Among the numbers of electrode materials of supercapacitor, carbon-based materials are the mostly widely used electrode materials due to their large surface area, relatively good electrical properties and moderate cost. In this work, we prepared the PAN nanofibers by a method of electrospinning, then composite with graphene oxide. We compared the electrochemical properties of different composite nanofiber prepared in different method. The main contents include as follows:PAN nanofibers was prepared by a method of electrospinning, then it was comopsite with GO. The porous carbon material was prepared by pre oxidetation, carbonization and activation by KOH. The results show that the composite carbonfiber was porous carbon materials. The demonstrate shows that composite materials shows the most excellent electrochemical performance when the graphene presents is 3%. The specific capacitance of the composite material reaches 402.1 F/g at the current density is 0.05 A/g, and it can be maintained at 239.2 F/g even at a high discharge current of 20 A/g. However, the values of the material without graphene are only 287.9 F/g and 110.0 F/g, respectively.PAN@GO nanofibers was prepared by pre-oxidetation, carbonization and activation with the same method. The result shows that the morphology of PAN@GO did not change significantly compared with PAN nanofibers. It also shows that the electrochemical performance of PAN@GO-based carbon material is better than PAN-based carbon material. When the graphene coated precent is 1%, the specific capacitance of PAN@GO-based carbon material is 365.5 F/g at the current density is 1 A/g, while the values of PAN-based carbon material is 318.7 F/g.We composite PAN@GO nanofiber with GO repeatedly to make carbon-based hierarchically nanofiber, and study the effects of different carbonization conditions on the performance of the storage material. The results showed that in the cooling process after the reaction with the air, hierarchically nanofibers have excellent rate performance and cycle stability. At a current density of 1 A/g, the specific capacity is 212.0 F/g, when the current density increases to 50 A/g, its specific capacity can still reach 150.5 F/g. Moreover, In the current density of 5 A/g, the cycle capacity retention rate after 2000 times is as high as 95.48%.