Synthesis Of N-doped Mesoporous Carbon Spheres And Their Mesoporous MnO_x Composites For High Efficient Electrochemical Performance

Supercapacitors with fast charge rate,high power density,long cycle life and big suitable temperature range are known as environmentally friendly electrochemical capacitors.Lots of experiments have been carried out in order to increase specific capacitance of supercapacitor.Carbon material is the maximum material used as the supercapacitor electrode.Carbon material with specific morphology and large surface area,heteroatom doping carbon materials(N,B,P,S)and carbon/metallic oxide composite which improve specific capacitance of supercapacitor have been studied.However,mesoporous carbon is used as the supercapacitor electrode because of its advantage containing large surface area,pore volume and narrow pore size distribution.Many researchers mainly focus on the preparation of heteroatom doping mesoporous carbon and mesoporous carbon/metallic oxide composite.N-doped mesoporous carbon spheres and N-doped mesoporous carbon spheres/MnOx composite were synthesized in the paper.We studied on the electrochemical performance of N-doped mesoporous carbon spheres and N-doped mesoporous carbon spheres/MnOx composite.(1)First,N-doped mesoporous carbon spheres were synthesized using soft template and hard template method.Monodisperse N-doped mesoporous carbon spheres were obtained by adjusting calcination temperature and pH.We chose m-aminophenol to insure N-doped carbon Network.The content of nitrogen in N-doped mesoporous carbon spheres are above 5 wt%.We obtained N-doped mesoporous carbon spheres and N-doped lychee exocarp-like mesoporous carbon spheres through adjusting the amount of TEOS.Then,N-doped core-shell mesoporous carbon spheres were obtained by changing the experiment condition.According to the formula C=It/m?E,the specific capacitance of NMCs,NLEMCs and NCSMCs is 262.4,323.2 and 247.06 F/g at a current density of 0.2 A/g.The cycling stability of three carbon material electrodes were examined using galvanostatic charge-discharge cycling at a current density of 5 A g-1.The specific capacitances remain at about 85%,which demonstrates good cycle performance.NLEMCs show the higher specific capacitance than NMCs and NCSMCs at a current density of 0.2 A/g.N-doped lychee exocarp-like mesoporous carbon spheres with different grain diameter had been synthesized by adjusting the amount solvent.The specific capacitance of NLEMCs-260,NLEMCs-420 and NLEMCs-620 is 345,323.2 and 222 F/g at a current density of 0.2 A/g.(2)N-doped lychee exocarp-like mesoporous carbon spheres/MnOx composite(NLEMCs/MnOx)were synthesized in high temperature.NLEMCs/MnOx-3-30,NLEMCs/MnOx-3-50 and NLEMCs/MnOx-3-70 were synthesized by adjusting the amout of potassium permanganate.According to the formula C=It/m?E,the specific capacitance of NLEMCs/MnOx-3-30,NLEMCs/MnOx-3-50 and NLEMCs/MnOx-3-70 is 207.7,243.5 and 251 F/g at a current density of 0.5 A/g.The capacitance of NLEMCs/MnOx-3-70 is highest.NLEMCs/MnOx-3-70 has higher capacitance with increasing current density.NLEMCs/MnOx-3-70 can be used as the supercapacitor electrode.