Synthesis Of Biomass-based Nitrogen Doped Porous Carbon Materials For Supercapacitor

Energy and environmental issues are key issues for sustainable human development.As a new type of energy storage device,supercapacitors have attracted widespread attention.The porous carbon material is widely used in capacitor materials because of its good chemical stability,low cost and good electrical conductivity.In order to further improve the electrochemical performance of the porous carbon material,nitrogen is usually introduced into the porous carbon material to enhance its surface wettability and active sites.In this topic,waste biomass is a carbon source,and nitrogen-doped porous carbon materials are prepared through the introduction of an additional nitrogen source.The main work is as follows:?1?Synthesis of nitrogen-doped porous carbons by utilising waste longan shell as carbon source and carbamide as additional nitrogen source through KOH activation at600°C–900°C for 2 hours under N₂ atmosphere.The obtained porous carbons possess highly-developed ultra-micropores?approximately 0.6 nm?,an ultrahigh specific surface area(up to 3260 m² g^-1)and a nitrogen content of 2.3 at.%.The porous carbon exhibits excellent electrochemical properties(a high specific capacity up to 322 F g^-1and an energy density of up to 20.4 W h kg^-1)at a current density of 0.5 A g^-1 in 6 M KOH and an excellent cycle stability?retained almost 96.2%specific capacitance after5000 cycles?.At the same time,we compared the properties of undoped nitrogen and discussed the effect of nitrogen doping on the electrochemical performance of the material.These results show that our nitrogen-doped porous carbon materials have broad application prospects in the field of supercapacitors.?2?On the basis of nitrogen plays an important role in electrochemical performance.This chapter is devoted to studying porous carbon materials with high nitrogen content and high specific surface area.Utilise water chestnut as a carbon source and melamine as a nitrogen source,study the effect of different activation methods?CO2 and KOH?on the material structure and specific surface area.The results indicated that the surface area of C-900-CO₂ by CO₂ activated is only 1175 m² g^-1,while the surface area of ANCs-3-700 by KOH activated is up to 3401 m² g^-1.The electrochemical performance is tested in a 6 M KOH solution,ANCs-3-700 with a high specific capacity of 346 F g^-1 and a high energy density of 22.4 W h kg^-1 at a current density of 0.5 A g^-1.It also exhibits an excellent cycling stability with a retention of nearly 97.6%capacity after 5000 cycles at 1 Ag^-1.