Preparation Of Cotton Seed Husk-based Porous Carbon Material For Supercapacitors

In this paper,cotton seed hulls are used as raw materials to prepare supercapacitor electrode materials,and three types of porous carbon materials are prepared by three methods:direct carbonization-activation,hydrothermal carbonization-activation,and direct carbonization of cottonseed hulls and hydrothermal composite with glucose carbon ball.During the preparation process,the pore structure and electrochemical properties of the carbon materials are adjusted by changing the process conditions.Cotton seed hulls were directly carbonized and hydrothermally carbonized to prepare cotton seed hull-based carbon materials,and then the carbon materials were chemically activated with KOH as an activator to obtain porous carbon materials HPCk and SPCk,respectively.Studies have shown that the porous carbon materials prepared by these two methods are used for energy storage in the form of electric double layers.In the preparation of HPCk by the direct carbonization-activation method,when the mass ratio of HPC to KOH is 1:3 and the activation temperature is700 ℃,the carbon material（HPCk-3）prepared after activation for 60 min has a rich microporous structure and a large specific surface area.Its specific surface area reaches 2599.1 m²g^-1,the specific capacitance of HPCk-3 at 0.5 A g^-1is 346.3 F g^-1,and the capacity retention rate is 90.4%after 8000 cycles.In the preparation of SPCk by the hydrothermal carbonization-activation method,the mass ratio of SPC to KOH is 1:2,and the carbon material（SPCk-t90）prepared by activation at 700 ℃ for 90 min has better electrochemical performance.The specific capacitance is 298.1 F g^-1,and the capacity retention rate is 96.1%after 8000 charge-discharge cycles.By comparing the SEM images of HPCk-3 and SPCk-t90,it is found that there is a big difference in the microscopic morphology of the two.HPCk-3 shows a relatively regular honeycomb structure,while the shape of SPCk-t90 is similar to coral.The difference in microscopic morphology also leads to greater differences in their pore structure,specific surface area and electrochemical performance.The specific surface area of??SPCk-t90 is 4104.7 m²g^-1,which is much higher than that of HPCk-3.In addition,in terms of electrochemical performance,although HPCk-3 has a larger specific capacitance at a lower current density,when the current density increases,the specific capacitance decreases significantly,while SPCk-t90 is significantly better than the rate performance and cycle performance.HPCk-3.In addition,in this paper,the cottonseed hull/carbon nanosphere composite material HPCk@GB-1 was prepared by hydrothermally treating cottonseed hull charcoal with glucose,and then through the KOH one-step activation method.Studies have found that glucose carbon spheres can increase the diversity of the composite pore structure and increase its specific surface area,and show a higher specific capacitance under the three-electrode system.The composite HPCk@GB-1 prepared when the glucose addition is 10 g The specific capacitance of is 308.8 F g^-1.This paper has 73 pictures,18 tables,and 102 references...