| Porous carbon is widely used in the fields of energy storage,adsorption and catalyst support due to its excellent physical and chemical properties.There are two main methods for preparing porous carbon materials,namely,template preparation and activation preparation.The template method is difficult to play a role in large-scale applications due to its disadvantages such as time-consuming,tedious synthesis process and high cost.At the same time,the removal of the template needs to use hydrofluoric acid or corrosive alkali,which is cumbersome and highly corrosive.Activation method is the most common and mature technical route for the preparation of porous carbon materials,which can be divided into chemical activation method and physical activation method.Among them,the chemical activation method can etch a large number of micropores in a short time to obtain porous carbon materials with high specific surface area.However,this method also has the problem of serious corrosion of equipment caused by alkali vapor generated during the activation process,as well as environmental pollution.The physical activation method is relatively simple mild and environmentally friendly,but it is difficult to obtain porous carbon materials with high specific surface area through conventional physical activation.Therefore,a new synthetic strategy for porous carbon materials with simple process,mild conditions,environment-friendly was studied in this paper.Coal-liquefied asphalt is a kind of high-quality precursor for carbon materials.The use of coal-liquefied pitch to prepare porous carbon with developed pore structure and high specific surface area and its application in the field of energy storage provides a new idea for the high value-added utilization of coal-liquefied pitch.In this paper,coal-liquefied pitch is used as a carbon source to prepare porous carbon materials.The specific research contents are as follows.Using Coal-liquefied asphalt as a raw material,a high specific surface area porous carbon material was successfully prepared through chemical cross-linking and subsequent CO2 activation process.After chemical cross-linking,the size of coal liquefied asphalt is obviously reduced,the oxygen content is obviously increased,and it has a three-dimensional cross-linked structure,which provides convenience for the subsequent CO2 activation.Due to changes in the composition and structure of precursor after chemical modification,the specific surface area and pore volume of sample?-CLR-8h-900-4h are as high as 2179.32 m2 g-1 and 2.61 cm3 g-1 when the chemical crosslinking time was 8h,activation temperature was900℃and activation time was 4h.The sample is used as an electrode material in a capacitor for performance testing.Compared with other materials,the sample?-CLR-4h-900-4h has the best capacitance performance.At a current density of 100 m A g-1,the specific capacitance is151 F g-1,at a current density of 2000 m A g-1,the specific capacitance is 90 F g-1.Nitrogen doped porous carbon was prepared by chemical crosslinking and CO2activation using coal liquefied asphalt as carbon source and melamine as nitrogen source.The chemical crosslinking treatment of coal liquefied asphalt can change the pore structure and surface chemical composition of precursor.The nitrogen content,specific surface area and pore volume of the samples obtained by chemical crosslinking of coal liquefied asphalt are significantly increased,and the nitrogen content is 3.52 wt.%,and the specific surface area value is up to 1119 m2 g-1.The pore volume is 0.93 cm3 g-1.In the three-electrode system,when the current density of 6M KOH electrolyte is 100 m A g-1,the chemically cross-linked sample has a large mass specific capacitance of 139 F g-1.When the current density reaches1000 m A g-1,the mass ratio capacitance can still reach 109 F g-1.At the current density of 1 A g-1,the capacitance retention rate of the two-electrode system is more than 95%after 5000cycles of charge and discharge,showing good cycling stability. |
