Preparation And Electrochemical Performance Of Modified Rice Husk Based-activated Carbon

Supercapacitors have high power density,excellent reversibility,and long cycle life,which have attracted worldwide attention.Carbon materials are widely used as electrode materials in supercapacitors,activated carbon as the main carbon material is the current research.Rice husks can be used as raw materials for activated carbon,rice husk-based activated carbon is also used in supercapacitor.There are also many problems of rice husk-based carbon,such as low tap density,poor volumetric capacitance performance,and unsatisfactory cycling stability,which seriously limits rice husks.In this paper,different methods were used to modify the rice husk-based activated carbon,and the electrochemical properties were systematically studied.The main research results are as follows:1.Rice husk-based activated carbon was modified by the surface modification of pitch.When the mass ratio of pitch to rice husk-based activated carbon was 1:5 and the heat treatment temperature was 400°C,the specific capacitance of rice husk-based activated carbon in organic electrolyte is 139.42 F/g,and the volumetric capacitance is 43.91 F/cc,which is higher than the volumetric specific capacitance of unmodified rice husk activated carbon?33.84 F/cc?.The retention of specific capacitance after10000 cycles of charge and discharge was 91.77%,which was higher than that of unmodified rice husk based activated carbon?84.44%?.The best specific capacitance in 6 mol/L KOH electrolyte was 178.74 F/g.The retention of specific capacitance after 10000 cycles of charge and discharge was 114.84%,which was better than 91.07%of the unmodified rice husk-based activated carbon.2.Pitch was used to composite modification of desilicon rice husk carbon,and coactivated to prepare modified rice husk activated carbon.When the mass ratio of pitch to rice husk carbon is 1:4 and the activation temperature is 700°C,the mass specific capacitance is 282.76 F/g,the volumetric capacitance is 72.10 F/cc in 6 mol/L KOH electrolyte,better than the untreated 237.01 F/g and 56.11 F/cc,after 20000cycles of charge and discharge,the specific capacitance retention rate was 95.01%,better than the untreated 88.71%;3.LHAJLU solution was used to pretreat rice husk to change the process of pyrolysis.When the mass concentration of LHAJLU was 5%,the yields of carbonization and activation of rice husk were 51.00%and 34.16%,respectively,which were higher than those of untreated rice husks?35.50%and 27.39%?.The tap density of rice husk-based activated carbon was increased from 0.27 g/cm³ to 0.31g/cm³,and the mass specific capacitance in 1 mol/L H₂SO₄ electrolyte was 283.56 F/g,the volumetric specific capacitance is 74.22 F/cc,and the capacitance retention rate after constant current charge and discharge 10000 times is 99.03%,which is better than untreated rice husk-based activated carbon?231.49 F/g,54.96 F/cc,and 91.49%?;The mass specific capacitance in the 6 mol/L KOH electrolyte was 269.62 F/g,the volumetric specific capacitance is 71.04 F/cc,and the capacitance retention rate after10000 cycles of charge and discharge was 94.63%,which was better than untreated rice husk-based activated carbon?247.19 F/g,56.74 F/cc and 90.81%?.In this paper,rice husk activated carbon was prepared by different modification methods,the tap density,volumetric capacitance,and cycle stability of activated carbon were improved,which provided an effective research idea for improving the electrochemical performance of supercapacitor electrode materials.