Fabrication And Electrochemical Performance Of Cellulose Porous Carbon For Supercapacitor Electrode Materials

The low capacitance storage of carbon-based electrical double layer supercapacitor（EDLC）has limited its application development,and the capacitance is mainly determined by the porous structure and elemental composition of the carbon electrode.Therefore,the development of porous carbon electrode with reasonable pore distribution and appropriate functional groups can effectively improve the EDLC capacitance.Cellulose has high carbon content and rich surface functional groups,which is a potential renewable material.In this project,filter paper was used as cellulose source and carbon precursor,and three kinds of cellulose porous carbons with different structures were prepared through different technical routes and applied to EDLC electrodes.The concrete research results are as follows:（1）Three-dimensional honeycomb-structured cellulose carbon aerogels were prepared by freeze-thaw regeneration,supercritical CO₂drying and N₂pyrolysis of cellulose filter paper.Its specific surface area was 327.6 m²g^-1,and it has a good hierarchical porous distribution.The carbon aerogel electrode exhibits a high specific capacity of 194.0 F g^-1.（2）Three-dimensional cobweb activated carbon with high specific surface area(1619.9 m²g^-1)and high oxygen content（15.91%）was prepared by two-step KOH carbonization-activation method using filter paper as precursor.The good pore distribution and appropriate oxygen functional groups of the activated carbon electrode promoted the synergistic effect of the electrical double layer capacitance and pseudocapacitance in the system,showing an excellent specific capacitance(310.3 F g^-1),The symmetrical capacitor assembled with it also showed high energy density(8.25 Wh kg^-1).（3）The cellulose porous carbon paper with strong self-supporting,high specific surface area(1693.3 m²g^-1)and high carbon yield（31.4%）was prepared by Cu Cl₂one-step pore-forming method.The porous carbon paper maintained the original fiber entanglement structure of the filter paper under the action of Cu Cl₂,and has well-developed interconnected microporous channels,showing the unique dual properties of capacitance activity and self-collecting fluid.The cellulose porous carbon paper prepared in this subject can be directly used as electrode without any additives and external current collectors.The energy density of the symmetric supercapacitor prepared with the porous carbon paper as electrode was as high as 12.54 Wh kg^-1,which has grand application potential.