Preparation And Electrochemical Performance Of Anode Materials For Lithium-ion Batteries By Spent Carbon Anode From Electrolytic Aluminum

Spent carbon anode（SCA）produced in the aluminum electrolysis process is classified as hazardous solid waste because it contains a certain amount of fluoride.In recent years,as the country attaches importance to environmental and resource issues,the harmless treatment and resource utilization of SCA has become an urgent problem to be solved in the aluminum electrolytic industry.In this thesis,for the purpose of harmless and efficient resource utilization of SCA,through chemical leaching,high-temperature graphitization and surface coating modifi cation treatments of SCA,an-excellent performance lithium-ion battery anode electrode material was prepared and the preparation process of SCA-based anode electrode material was developed.The main research contents are as follows:（1）The chemical leaching process is used to recover the carbon materials in the SCA,and the influence of factors such as leaching time,leaching temperature,leaching concentration and leaching liquid-solid ratio on the SCA recovery process is explored through orthogonal experiments.The results show that under the optimal process condition,the SCA impurity removal rate is 48%,the carbon purity of SCA-CL can reach 93%,and the structure remains unchanged during this process.The optimal process condition:the alkali leaching temperature is 110℃,alkali leaching time is120 min,alkali leaching solution concentration is 15%,alkali leaching solution solid ratio is 10:1;And the acid leaching temperature is 90℃,acid leaching time is 80 min,acid leaching solution concentration is 15%,acid leaching solution solid ratio is 15:1.And the acid filtrate and alkali filtrate are mixed to produce cryolite with a purity of98%,which can be recycled as electrolytic aluminum electrolyte.（2）The SCA-CL was further purified by high-temperature graphitization process to prepare SCA-CL-280,and its feasibility as a lithium-ion battery anode material was explored.The results show that the carbon purity of SCA-CL-2800 is increased to99.90%,the graphitization degree is 81.56%,and it has surface micro-defects and a highly ordered graphite sheet structure.SCA-CL-2800 shows excellent electrochemical performance as an anode material for lithium-ion batteries.The first charge capacity is359.1 m Ah g^-1,and the first coulombic efficiency is 80.17%.After 50 cycles,its reversible capacity remains 368.6 m Ah g^-1.Compared with commercial graphite,SCA-CL-2800 has better reversible capacity,excellent cycle stability and rate performance.（3）Through surface coating modification,the relationship between different glucose coating amount and electrochemical performance was explored,and the problem of low coulombic efficiency of SCA-CL-2800 for the first time was solved.The results show that when the amount of glucose co ating is 5 wt%,the glucose coated on the surface of the SCA-CL-2800 is more uniform,reducing the consumption of irreversible Li⁺,with the first coulombic efficiency reaching 84.37%and the good rate performance and cycle performance.