Microstructure Control And Electrochemical Properties Of Renewable Porous Carbon Materials

Porous carbon materials are widely used in various fields of electrochemistry as electrode materials due to their advantages of simple preparation,environmental friendliness and controllable morphology.The rational design and effective preparation of porous carbon electrode materials using renewable organic wastes are of great significance for the optimization of electrochemical energy devices.Renewable porous carbon materials with unique microstructures are more helpful to meet the requirements of effective preparation of electrode materials.How to effectively screen the porous carbon materials that meet the application requirements and establish the quantitative correlation degree between material structure and performance application have become one of the concerns in the field of electrode materials development.Therefore,this thesis developed renewable porous carbon materials using biomass and waste polymers as carbon sources,combined the analysis of material microstructure characterization and its performance evaluation,proposed the correlation between pore accumulation ratio and application performance of electrode materials,realized the goal of precise regulation of material microstructure,and develops the application prospects of renewable porous carbon materials in electrochemistry by the idea of quantifying"material structure"and correlating"performance application".The research content mainly included the following aspects:（1）The renewable porous carbon materials were prepared by direct carbonization method and single activator（KOH or Zn Cl₂）activation method,respectively,from the carbon source of hay slag.The results showed that,compared with the direct carbonization method,the KOH single activation method produced many micropores,and the Zn Cl₂single activation method formed the multistage pore structure.The porous carbon materials’specific surface area and pore volume were improved.When the current density was 1 A/g,The corresponding specific capacitance was increased to 222.23F/g and 226.20F/g respectively.（2）In order to further enrich the multistage pore structure of the renewable porous carbon material,the renewable porous carbon material was prepared by one-step activation carbonization method with two metal salts Zn Cl₂and Mg（NO₃）₂·6H₂O as the carbon source of biomass.The results showed that the porous carbon material prepared by the double activator method had a more obvious multistage pore structure.When the current density was 1 A/g,its specific capacitance can reach 230.10F/g.By analyzing the correlation between the cumulative pore ratio and the specific capacitance,it can be concluded that the optimal pore size range for electrochemical capacitance performance was 0.8-1.2 nm.At the same time,the porous carbon material prepared by the double-activator method also had a higher CO₂adsorption capacity.Under 0℃and 1 bar conditions,the highest CO₂adsorption capacity was 3.09 mmol/g,and the optimal pore size required for its adsorption performance was 0.5-0.8 nm.（3）To verify the applicability of the dual activation method and further improve the performance of renewable porous carbon materials,polyethylene terephthalate was used as a waste polymer carbon source,and two metal salts,Zn Cl₂and Mg（NO₃）₂·6H₂O,were also selected as double activators to prepare renewable porous carbon materials by two-step activation carbonization method.It is shown that based on the structural orientation of Mg O template,the porous carbon materials prepared from waste polymer carbon sources by the double activator method possess a lamellar structure,and the abundant lamellar structure is also beneficial to enrich the multi-level pore structure of the materials.Therefore,the abundant micropore structure（0.5-0.7 nm）of the corresponding renewable porous carbon material enabled it to have an appropriate specific capacitance and a higher CO₂adsorption capacity（3.79 mmol/g）.