| The increasing depletion of fossil resources has promoted the development of efficient utilization of natural renewable resources.Supercapacitor is a new type of green energy storage device,and electrode material is an important device to determine its performance.In this paper,lignin extracted from paper black liquor is used as the carbon source,and inorganic(diatomaceous earth),metallic(nickel foam)and organic(polyurethane foam)are used as templates to prepare lignin-based template carbon materials,which are treated by catalytic graphitization and activation to obtain supercapacitor electrode materials with excellent performance.The electrochemical properties and corresponding performance were characterized and analyzed to optimize the method of lignin template carbon preparation and conclude the best preparation process.The main research work and conclusions are as follows.(1)Using black liquor lignin as the carbon source and diatomaceous earth as the inorganic template,high-temperature carbonization and hydrothermal activation are used to prepare ordered diatomaceous earth template carbon.The effects of carbonization temperature and the mass ratio of diatomite to lignin on the electrochemical performance of template carbon were systematically studied,and various diatomite template carbon materials prepared were comprehensively compared.The mass ratio of lignin/diatomite was 1:1.After being carbonized at 900℃ for 2 h,the template carbon electrode material prepared by hydrothermal activation at 180℃ for 10 h has a hollow tubular structure,and there are a large number of micropores and mesopores on the tube wall,and the specific surface area is 321.7 m2/g,The material has good electrochemical performance.When the current density is 0.5 A/g,the mass specific capacitance can reach 207.7 F/g;and when the current density is 2.0 A/g,the specific capacitance retention rate still reaches 95.4%after 5000 cycles of charging and discharging;the assembled symmetrical capacitor When the current density is 2.0 A/g,the specific capacitance reaches 122.2 F/g;When the power density is 2.4 kW/kg,its energy density is 17.0 Wh/kg,indicating that the prepared lignin-based template carbon material has a good electrochemical performance.(2)Using foamed nickel as a metal template and black liquor lignin as a carbon source,CNTs were grown in the pores of the foamed nickel by chemical vapor deposition,and then activated by KOH to prepare a foamed nickel composite CNTs electrode.The influence of composite CNTs on the electrochemical performance.When the growth temperature is 1100℃,a large number of carbon nanotubes grow on the pores and surface of the nickel foam.The electrochemical test shows that when the current density is 0.1 A/g,it has a mass specific capacitance of 317.4 F/g,and the specific capacitance retention rate is still 88.0%at a current density of 2.0 A/g for 5000 cycles.(3)Using polyurethane foam as the organic template and black liquor lignin as the carbon source,NiCl2·6H2O was selected as the catalyst to prepare Ni doped polyurethane foam template carbon.The original and auxiliary materials were screened through single factor and orthogonal experiments.When the concentration of NiCl2·6H2O solution is 40%,and the addition amount of lignin and PF resin are 2.0 g and 7.5 g,respectively,the carbon template obtained has good electrochemical performance.And using this as a template,the polyurethane foam composite CNTs material was prepared by chemical vapor deposition.The results show that the sample has excellent electrochemical properties at sintering temperature of 1000℃ and a specific capacitance of 284.4 F/g at current density of 0.1 A/g,at a current density of 0.5 A/g for 5000 cycles,the capacity retention is 89.5%. |
