Preparation And Electrochemical Properties Of Coal Tar Pitch-Based Porous Carbon Electrode Materials

The pollution caused by the overexploitation of fossil energy has far exceeded the impact that the ecological environment can bear.How to develop,utilize and store new energy to alleviate the environmental damage caused by fossil energy is imminent.As a new type of energy storage element,supercapacitors are favored by researchers because of their high energy density and long cycle life,among which the electrode materials that play a key role have received much attention.Porous carbon materials have been used as electrode materials for energy storage devices due to their high specific surface area,abundant pores,and high electrical conductivity.my country’s coal resources are very rich.In 2021,China’s raw coal output will exceed 4 billion tons,and the output of coal tar as a by-product of coal chemical industry will also increase.In this paper,coal tar pitch was used as raw material to prepare porous carbon materials by different means and their electrochemical properties in a three-electrode system were investigated.The main research contents are as follows:Firstly,coal tar-based porous carbon was obtained by hydrothermal carbonization and KOH activation after pre-oxidation with coal tar pitch.The effects of different activation temperatures and hydrothermal carbonization on the performance of porous carbon materials were investigated.At the optimal activation temperature of 800°C,the addition of lysine in the hydrothermal process prepared a high specific surface area of 1467 m~2/g and abundant micro-mesoporous porous carbons.The porous carbon electrode material was tested in a three-electrode system and found to exhibit typical electric double-layer capacitance characteristics and a high specific capacitance of 289F/g at a current density of 0.1 A/g.Experiments show that the addition of lysine to the hydrothermal carbonization improves the specific surface area and pore structure of porous carbon,and also improves its electrochemical performance.Secondly,using pre-oxidized coal tar pitch as raw material,melamine as foaming agent,and nano-calcium carbonate as hard template agent,coal tar-based porous carbon rich in micro-mesopores was prepared by carbonization activation.The specific surface area of the prepared porous carbon was as high as 1072 m~2/g due to the influence of carbon structure and electrochemical performance.It has a high specific capacitance of225.6 F/g in the three-electrode system,and exhibits a high capacitance retention rate of 97.29%in the two-electrode system.Experiments show that the introduction of nano-calcium carbonate can increase the specific surface area of porous carbon and control its pore structure,which can significantly improve the electrochemical performance of porous carbon electrode materials.Finally,using pre-oxidized coal tar pitch as raw material,coal tar pitch-based porous carbon with a large number of mesopores was prepared by carbonization activation method using nano-calcium carbonate and sodium chloride salt double-template method.The effect of the porous carbon on the pore structure and electrochemical properties,the coal tar-based porous carbon with a specific surface area up to 1474 m~2/g was prepared experimentally.The porous carbon electrode material in the three-electrode system exhibits typical electric double-layer capacitance characteristics and has an ultra-high specific capacitance of 375 F/g at a current density of 0.1 A/g,which is higher than most previous studies on coal tar porous carbon reported electrochemical performance.Experiments show that the activation temperature and the ratio of activator can effectively improve the specific surface area of porous carbon and improve its electrochemical performance.