炭化对人造石墨负极材料性能影响的研究

Effect of carbonization on the properties of artificial graphite anode materials

锂离子电池以高能量密度、高循环性能、绿色环保等众多优势备受关注,开发高性能、低成本的炭类负极材料是改善锂离子电池性能的主要研发方向。在制备炭负极材料的过程中,为了避免石墨化过程温度过高,小分子挥发速度过快,引起烟量过大这一缺陷,在包覆造粒和石墨化过程中先进行炭化处理,既可以加速沥青的热分解和热缩聚过程,又缩短石墨化反应时间。通过激光粒度仪、比表面积测试仪、电化学性能测试等手段进行研究发现,经过炭化处理和未经炭化处理的人造石墨负极材料的粒度分布、首次库伦效率、首次充放电比容量均受到影响。增加炭化处理后,可改变人造石墨负极材料的粒度分布,在合格范围内D50越大,颗粒分布越宽,固含量越高,涂布难度越小;增加炭化处理后,人造石墨负极材料的比表面积变小,锂离子的迁移通道增多,增加了样品的倍率性能;增加炭化处理后,人造石墨负极材料的石墨微晶层面排列较规范,进而使首次库伦效率和首次充放电容量都得到有效提升。

Lithium-ion batteries have attracted much attention due to their high energy density,high cycle performance,low self-discharge rate,green environmental protection and many other advantages.In the future,the development for high performance and low cost carbon anode materials is the main research and development direction.In the process of preparing carbon anode materials,in order to avoid the defects of too fast volatilization of small molecules and too much smoke due to high temperature in graphitization process,the carbonization treatment is required first in the process of coating granulation and graphitization,which can not only accelerate the thermal decomposition and thermal condensation process of pitch,but also shorten the graphitization reaction time.The performance and structure of the carbon anode materials are characterized by means of laser particle size analyzer,surface area tester,electrochemical performance test and other methods.It is found that the particle size distribution,the first Coulomb efficiency and the first charge-discharge specific capacity of artificial graphite anode materials with/without carbonization treatment were all affected:the particle size distribution of the artificial graphite anode material with carbonization treatment can be changed,and the larger the D50is,the wider the particle distribution is,the higher the solid content is,and the less difficult the coating is;the specific surface area of the artificial graphite anode material with carbonization treatment decreases,the migration channels of lithium ions increase,and the sample rate performance is increased;the graphite microcrystal layer arrangement of artificial graphite anode material with carbonization treatment is more standard,so that the first efficiency and the first charge and discharge capacity are effectively improved.