Preparation Of N-doped Porous Carbon Materials And Their Application In Supercapacitors

At present,nitrogen-doped porous carbon materials have been one of the hotspots in the field of carbon materials.Nitrogen-doping in the carbon matrix can form pyridinic-N,pyrrolic-N,graphitic-N,and pyridinic-N+-O functionalities,which can adjust the surface chemical activity of the carbon materials,and improve their electronic conductivity together with their electrochemical performances.Nitrogendoped porous carbon materials used as supercapacitor electrode can produce Faradaic capacitance and enhance the electrode wettability in aqueous electrolytes,therefore endowing carbon materials with the significant improvement of specific capacitance and rate capability.In this thesis,two kinds of nitrogen-doped porous carbon materials were prepared by using ammonium citrate as well as the mixture of monoammonium citrate and poly?N-?2-aminoethyl?methacrylamide??PAEMA?as the precursors.The electrochemical properties of these nitrogen-doped porous carbons as supercapacitor electrode materials were also investigated.The main research contents were shown as follows:?1?Preparation and capacitance performance of nitrogen-doped porous carbons derived from ammonium citrate.Nitrogen-doped porous carbon materials?ACAs?have been prepared by carbonization of ammonium citrate single precursor followed by KOH activation.The nitrogen-doped porous carbon,ACA-6-2-8,fabricated under optimal conditions?carbonization temperature is 600 °C,mass ratio of KOH/pyrolysis carbon is 2/1,and the activation temperature is 800 °C?has a finely-layered schistose architecture,and simultaneously has a very high specific surface area(2660 m2 g^-1),and total pore volume(1.40 cm3 g^-1)as well as a relatively high nitrogen content?1.37 at.% N?.In 6 M KOH aqueous electrolyte,the ACA-6-2-8 electrode displays both high capacitive and ultrahigh-rate performances with a specific capacitance of296 F g^-1 at 100 A g^-1,at least 80.4% of its maximum capacitance(368 F g^-1)at 1 A g^-1.Moreover,symmetric supercapacitor assembled using the same two ACA-6-2-8electrodes in 1 M Na2SO4 aqueous solution offers a high energy density of 25.5 Wh kg^-1 at 923 W kg^-1 as well as excellent cycling stability(only 4% of capacitance loss after 10000 cycles with a cell voltage of 1.8 V at a current load of 2 A g^-1).?2?Preparation and capacitance performance of polymer-derived nitrogen-doped porous carbon.Nitrogen-doped porous carbon materials were prepared by the directpyrolysis of poly?N-?2-aminoethyl?methacrylamide??PAEMA?and monoammonium citrate mixture precursor in the presence of BaCO3.The as-prepared nitrogen-doped porous carbon,APC-800-2,shows a medium specific surface area of 690 m2 g^-1 and a moderate pore volume of 0.53 cm3 g^-1 as well as a high N content of 5.07 at.% N.The APC-800-2 electrode exhibits a gravimetric capacitance of 207 F g^-1and a volumetric capacitance 201 F cm–3 at 0.5 A g^-1 and excellent cycling stability(above 95% of its initial capacitance after 10000 cycles at 2 A g^-1).