Preparation Of Heteroatom Doped Porous Carbon Material And Its Lithium Storage Performance

In this paper,heteroatom-doped porous carbon is studied,and a variety of porous carbon materials doped with different porous structures and different heteroatoms are prepared by simple,environmentally and friendly methods.And the relationship between their structure and electrochemical performance is studied by structural characterization and electrochemical characterization.The specific research contents are as follows:（1）Nitrogen-doped porous carbon is successfully prepared by self-sacrificial template method using polyacrylonitrile（PAN）as carbon source and1-Ethyl-3-methylimidazolium dicyanamide（[EMIm]N（CN）₂）as nitrogen dopant.The effects of self-sacrificial template and ionic liquid on the morphology of porous carbon,the degree and state of nitrogen doping,the electrochemical properties of nitrogen-doped porous carbon are investigated.The results showed that the nitrogen-doped porous carbon carbonized at 800°C has a nitrogen content of 3.8wt%and is mainly present in the form of pyrrole nitrogen and pyridinium nitrogen.As a anode electrode material for lithium ion batteries,it has excellent electrochemical performance.At the current density of 0.1 C,the first charge capacity can reach 1074.5mAh g^-1,and remains at 714.6 mAh g^-1 after 50 cycles.In addition,the reversible capacity can reach 427 mAh g^-1 at a current density of 1 C.（2）The nitrogen-sulfur co-doped porous carbon is successfully prepared by salt templatemethodusingglucoseascarbonsourceandionicliquid1-ethyl-3methylimidazolium hydrogensulfate（[EMIm]HSO₄）as nitrogen-sulfur co-dopant.The effects of different carbonization temperatures on the morphology,doping level and electrochemical performance of prepared nitrogen-sulfur co-doped porous carbon are investigated.The results show that the nitrogen content and sulfur content of the nitrogen-sulfur co-doped porous carbon carbonized at 800°C can reach2.32wt%and 0.91wt%,respectively.Electrochemical tests show that 800℃carbonized nitrogen-sulfur co-doped porous carbon has the best performance.The first charge capacity is 1168.9mAh g^-1 at a current density of 0.1 A g^-1,and the reversible capacity is maintained at 828.5 mAh g^-11 after 50 cycles.In addition,the reversible capacity still reaches 533mAh g^-1 after 1000 cycles at a current density of 1.5 A g^-1.（3）Based on the previous chapter,this chapter also uses glucose as a carbon source,1-Ethyl-3-methylimidazoliumhydrogensulfate（[EMIm]HSO₄）as nitrogen-sulfur co-dopant,and nitrogen-sulfur co-doped hierarchiacl porous carbon is prepared using different salt templates.The effects of different carbonization temperatures on the morphology,doping degree and electrochemical performance of the prepared nitrogen-sulfur co-doped hierarchiacl porous carbon are investigated.The effects of nitrogen and sulfur atoms on the charge storage mode of carbon materials and effect of capacitance behavior on cycle stability in lithium ion batteries are further studied.The results show that the nitrogen content and sulfur content of the nitrogen-sulfur co-doped hierarchiacl porous carbon carbonized at 800°C can reach4.66wt%and 1.83wt%,respectively.The electrochemical performance shows that the nitrogen-sulfur co-doped hierarchiacl porous carbon with carbonization at 800℃has the best performance.The first charge capacity of 1958.8 mAh g^-1 at a current density of 0.1 A g^-1 and the reversible capacity is maintained at 987.7 mAh g^-11 after 120 cycles.In addition,the reversible capacity remains at 337.5 mAh g^-11 after 5000 cycles at a current density of 5 A g^-1.