Study On Modification Of Carbon Aerogel And Performance Of Supercapacitor

Carbon aerogels(CA)is recognized as the ideal supercapacitor electrode materials due to its unique three-dimensional network structure,well-developed pore radius distribution,large surface area,and good electrical conductivity.The capacitance performance of the supercapacitor mainly depends on the specific surface area,pore radius distribution and structural properties of the electrode material.In this paper,through high temperature carbonation,activator activation and heteroatoms introduction approaches,the as-prepared carbon materials have been achieved based on CA modification,of which XRD,BET and SEM are employed to characterize the structure,and electrochemical tests to analyze the capacitance performance of the supercapacitor.The detail contents are mainly as follows:(1)Carbon nanospheres are prepared by high temperature carbonization using carbon aerogels as precursors.The specific surface and pore radius distribution analyzed by BET found that the specific surface increases from 83.20 m2 g-1 to 499.7 m2 g-1 and the pore radius distribution changes from disorder to order.Capacitor performance analysis of carbon nanospheres finds when the current density is 0.5 A g-1,the specific capacitance of CA-700 is 112.95 F g-1.Meanwhile,the as-prepared CA-700 also exhibits excellent cycling stability with 97.98%of the capacitance retention over 1000 cycles at a current density of 5 A g-1.(2)The nitrogen-doped carbon nanospheres(N-CA),which are polymerization-produced at high temperature using CA as precursors and melamine as nitrogen source.Nitrogen content is up to 19.95%verified by elemental analysis(EA).The specific surface analyzed by BET finds that the specific surface is as high as 458 m2 g-1.Capacitor performance analysis of N-CA shows when the current density is 0.5 A g-1,the specific capacitance is 210.45 F g-1.After 1000 cycles,superior capacitance was still maintained up to 88.56%at the high current density of 5 A g-1.(3)Porous carbons are activated through high temperature activation using carbon aerogels as precursors and sodium hydroxide as activators.The microstructure of the porous carbons is observed by SEM,which exhibits porous honeycomb surface structure.BET technique reveals that the obtained porous carbons possesses the high specific surface area of 2492.6 m2 g-1.Meanwhile,the as-prepared porous carbon delivers the biggest specific capacitance of 299 F g-1 at 0.5 A g-1.The long-term cycling stability with 99%of the capacitance retention over 1000 cycles,which can be ascribed to its unique 3D porous structure for the fast charging/discharging operation.(4)Nitrogen-doped porous carbons(NCA-1-1)are prepared by preliminary polymerization reaction and activated by high temperature of potassium hydroxide using carbon aerogels as precursors and urea as nitrogen source.The specific surface analyzed by BET finds that the specific surface is as high as 1342.17 m2 g-1.Capacitor performance analysis of NCA-1-1 finds when the current density is 0.5 A g-1,the specific capacitance is 276.05 F g-1.Over 1000 cycles,superior capacitance was still maintained up to 95.3%at the high current density of 5 A g'1.