Preparation And Electrochemical Properties Of Coal Bitumen Based Porous Carbon Materials

In order to address the instability of wind,solar and tidal energy sources,the development of new energy storage devices for storing energy for emergency purposes is key to solving ecological problems.However,with the increasing large-scale energy storage devices,higher demands are placed on their price,energy density,power density and other parameters,and there is an urgent need for researchers to develop more affordable battery electrode materials with high energy density and long cycle life.Coal tar pitch is an industrial by-product of coking in the iron and steel industry,and it is of strategic importance to combine high quality and low cost coal tar pitch with the new energy industry to produce high performance electrode materials to achieve effective use of resources.Based on this,the thesis focuses on the preparation of coal tar pitch-based electrode materials,with the main research content as follows:（1）Using medium-temperature Coal tar pitch（CTP）as carbon source and silica（SiO₂）as template agent,the spherical precursor of SiO₂/coal tar pitch composite was prepared by suspension method,and then the spherical porous activated carbon material was successfully prepared by non-melting,carbonization,pickling and activation.By adjusting the amount of silica as template agent,the spherical porous activated carbon material with good charge-discharge reversibility and double electric layer characteristics was prepared in the experiment.The specific capacitance of the material was 153.5 F g^-1 at the current density of 0.5 A g^-1.At the current density of 1 A g^-1,the capacity retention rate is 101.5%after 10000 cycles.（2）Nitrogen and phosphorus co-doped porous carbon materials were prepared by one-step carbonization method using medium-temperature Coal tar pitch（CTP）as carbon precursor,sodium chloride（Na Cl）as template agent and diammonium hydrogen phosphate（（NH₄）₂HPO₄）as nitrogen and phosphorus source.SEM,nitrogen adsorption and desorption tests,XRD tests and electrochemical tests show that the amorphous degree of nitrogen and phosphorus doped porous carbon is significantly higher than that of the porous carbon materials without nitrogen and phosphorus heteroatoms.Electrochemical test showed that the specific capacity of NPPC-3 reached 483.1 mAh g^-1 at the current density of 0.1 A g^-1 when the material was applied to lithium-ion batteries.（3）The activated nitrogen and phosphorus co-doped porous carbon material is applied to the supercapacitor.The effects of nitrogen and phosphorus doping ratio,carbonization temperature and activation temperature are discussed respectively.The experimental results show that the activated N-P co-doped porous carbon material has more developed micro/mesoporous pore structure,with the maximum specific surface area of 2280.7 m² g^-1,and the total pore volume mainly distributed in 0.8-1.2 cm³ g^-1,which gives the material a higher electrostatic adsorption capacity.When the current density is 0.5 A g^-1,the specific capacitance of ANPPC-3 electrode can reach 188.3 F g^-1,and when the current density is 5 A g^-1,the energy density and power density are5.8 Wh kg^-1 and 1217.6 W kg^-1,respectively.Under the premise of ensuring the power density,the energy density of the material is greatly increased.