Modified Preparation Of Porous Carbon Of Xinyang Coal And Its Preparation Supercapacitor Performance Research

To achieve pore type adjustment and regulation of micropore-to-mesopore ratio in hierarchical porous carbon,high surface area hierarchical porous carbon was prepared using Xin Yang coal as a carbon source and KOH as an activator.Biomass lotus leaves were used as an additive to adjust the micropore-to-mesopore ratio,and urea was added to further adjust the pore structure to increase specific capacitance while maintaining good rate performance and cycle stability.The micro-morphology,pore structure,and surface functional groups of the porous carbon and their effects on electrochemical performance were studied using SEM,FTIR,XPS,Raman,and pore size and surface analysis equipment,and the optimal process conditions for lotus leaf pretreatment,lotus leaf doping rate,and urea addition ratio were investigated.The results are as follows:（1）High surface area hierarchical porous carbon material with a certain O/N/S content was obtained by one-step high-temperature carbonization activation using Xin Yang coal as a precursor and KOH as an activator.The low-temperature activated porous carbon has a high O/N/S content and can contribute additional pseudocapacitance at low current density and low scan rate,which significantly improves the specific capacitance.As the activation temperature increases,the O/N/S content decreases,and the specific capacitance decreases accordingly.The optimal activation temperature for overall electrochemical performance was 750°C,where the hierarchical porous carbon had a specific surface area of 3693.5 m² g^-1,a specific capacitance of 327.8 F g^-1 at 1 A g^-1 current density,and a capacitance of 249.6F g^-1 at 20 A g^-1 current density,with a rate performance of 76.1%.After 8000 cycles,the specific capacitance remained at 90.8%,demonstrating good cycle stability.（2）Adding biomass lotus leaves can regulate the ratio of large mesopores to small mesopores in graded porous carbon.Graded porous carbon obtained by co-carbonizing lotus leaves and Xin Yang coal directly has a cheese-like morphology and mostly consists of isolated deep micropores.Lotus leaves pretreated with pre-carbonization and HNO₃treatment（lotus leaf carbon）and Xin Yang coal co-carbonized and activated to produce graded porous carbon with abundant hierarchical pore structure.By changing the lotus leaf carbon doping ratio,the ratio of large mesopores（1.5-2.2 nm）and small mesopores（2.7-4nm）can be effectively adjusted without significantly changing the pore volume of small micropores（0.8-1.5nm）,thereby further achieving synergistic improvement in electrochemical performance.When the ratio reaches an optimal state,even if the specific surface area of the porous carbon is similar,its specific capacitance can still be greatly improved.For example,sample S2PLC has a specific capacitance of 353.1 F g^-1 at 1 A g^-1current density and 270.7 F g^-1 at 20 A g^-1 current density,with a capacitance retention rate of 93%after 10000 cycles.（3）The addition of urea can adjust the pore structure of the porous carbon,improve the surface morphology of the porous carbon,generate a large number of interconnected pores,thus providing a smoother channel for electrolyte ion transport,and can improve the surface functional groups,thus further improving the electrochemical properties.The specific capacitance at a current density of 1 A g^-1 was increased to 376.7 F g^-1 and 289.0 F g^-1 at 20A g^-1 without a significant increase in specific surface area,while the cycling stability remained almost unchanged,demonstrating excellent electrochemical performance.There are 78 figures,19 tables and 128 references in this thesis.