Pore Structure Control Of Super-capacitors Electrode Materials Prepared From Dense Medium Components Of Coal

Porous carbon material was prepared by using dense medium component?DMC?as raw material,Nano-alumina?nano-Al₂O₃?as hard template or microcrystalline cellulose?MCC?as soft template,potassium hydroxide?KOH?as activator.The effects of template ratio?Nano-Al₂O₃:DMC?,activation ratio?KOH:DMC?,activation time and activation time on the structure of porous carbon were studied in this work.The structure was characterized by BET and SEM.The tests of cyclic voltammetry?CV?,constant current charge discharge?GCD?and AC Impedance Spectroscopy?EIS?were performed on supercapacitors assembled with porous carbon materials in a two-electrode system of an electrochemical workstation.When nano-Al₂O₃ was used as hard template,the porous carbon material with the large specific surface area of 2659 m²/g and a high total pore volume of 1.542cm³/g can be prepared under the ratios of DMC,nano-Al₂O₃,KOH is 1:2:3,and temperature of 750?,a large specific capacitance of 398 F/g is achieved at a current density of 0.1 A/g and it can retain a 250 F/g even at a current density up to2 A/g when measured in a two-electrode system,and rate performance is 63%,the retention of specific capacitance is still 73.4%after 4000 cycles of charge and discharge,the energy density and power density are 70.9 Wh/kg and 5431 W/kg.KOH and carbon reacts to certain micro-pores,nano-Al₂O₃ template coated with dense medium component effectively regulates the pore structure of carbon materials through its small size and unique pore structure,and it plays the role of a template agent for medium and large pores in the pore-forming process.At the same time,a suitable template agent can make dense medium component disperse to ensure the gas generated during the pyrolysis process can escape uniformly.When micro-crystalline cellulose was used as soft template,the porous carbon with the specific surface area of 4345 m²/g and a total pore volume of 2.086 cm³/g can be prepared under the ratios of DMC,MCC and KOH is 1:0.3:7,activation temperature of 650?,and activation time of 2 h,a large specific capacitance of 422F/g is achieved at a current density of 0.1 A/g and it can retain a 270 F/g even at a current density up to 2 A/g when measured in a two-electrode system,and rate performance is 67.2%.Micrometer-sized hollow tube is formed during the pyrolysis of micro-crystalline cellulose,covered by dense medium component plays a template role,On the one hand,it provides more activation sites for the molten KOH,and the rich microspore structure is etched,on the other hand,make dense medium component disperse to ensure the gas generated during the pyrolysis process can escape uniformly.Compared with microcrystalline cellulose as a template agent,the porous carbon prepared by nano-alumina has a better control effect on the pore structure and a high porosity.Compared with nano-alumina as a template agent,the porous carbon prepared by microcrystalline cellulose as template agent has a high specific surface area and a uniform pore size.There are 29 figures,18 tables and 98 references in this paper.