Porous Carbon Derived From Waste Tea As Supercapacitor For Energy Storgy Application

The porous carbon materials derived from biomass as carbon precursor have large specific surface area,which can provide a large number of active sites for electric double layer capacitive charge storage.The rich pore structure can effectively improve the charge storage capacity of carbon materials,but the current biomass-derived Carbon materials have cumbersome preparation steps,small specific surface area,unreasonable pore size distribution,and low heteroatom doping content,which restricts the application of carbon materials as supercapacitor electrode materials in energy storage.In order to solve the above-mentioned problems,the work of this thesis mainly studies the application research of using biomass waste tea as carbon precursor to prepare porous carbon as a supercapacitor in energy storage.The preparation of a three-dimensional porous carbon material with a reasonable pore size distribution,a large specific surface area and a rich heteroatom-doped sheet-like structure is realized,and it is used as a supercapacitor electrode material to realize energy storage applications.First,using waste biomass tea as a carbon precursor,porous carbon materials are prepared by the Na Cl/KCl molten salt method,where the Na Cl/KCl molten salt system is used as a high-temperature solvent and template,and the inert salt KCl helps in the process of activating the waste tea.The carbon material forms a sheet structure,which greatly improves the conductivity of the carbon material.The chloride ion in the molten salt system etches the carbon precursor to form a porous structure,which provides a large number of active sites for the electric double layer capacitor.By adjusting the amount of Na Cl/KCl,a three-dimensional porous sheet structure carbon material with reasonable pore size distribution,large specific surface area,doped with nitrogen,oxygen,and phosphorus heteroatoms can be prepared,and it is used as an electrode material when potassium hydroxide is used as an electrolyte.The measured capacitance value in the three-electrode system is 109 F·g^-1,showing good electrochemical performance.The three-dimensional porous sheet structure of the carbon material keeps the original structure at a higher current density,and the carbon material performs well cycle stability.Secondly,using waste biomass tea as the carbon source,KOH activation method is used to prepare porous carbon materials,the carbon precursor is etched through the high temperature oxidation process,and the KOH dosage is adjusted to obtain reasonable pore size distribution,large specific surface area,and doped with nitrogen,oxygen,and phosphorus.The three-dimensional porous carbon material with three heteroatoms has a capacitance value of 170 F·g^-1 measured in a three-electrode system with potassium hydroxide as the electrolyte.It is used as a symmetrical supercapacitor electrode material.The capacitance value in potassium hydroxide electrolyte is 42 F·g^-1.When the power density is 120 W·kg^-1,the energy density can reach 8.5 Wh·kg^-1.It shows that the preparation of three-dimensional porous carbon materials by adjusting the amount of activator shows good electrochemical performance and cycle stability,and the preparation of supercapacitor electrode materials by activating and degrading waste biomass has great application potential.