Needle coke was recognized as one of the most important precursor to produce ultra-high power graphite electrode, commercial anode materials for lithium-ion battery, and special graphite materials. It was generally accepted that the microstructure of needle coke has been acted as a key role on the quality of its derived graphite materials. In this work, four kinds of green needle cokes (coal-based green needle coke and petroleum-based green needle coke) have been used as the raw materials to investigate the changes of micro-structure during the calcination process. The micro-structure of needle cokes at different calcination temperature has been detailed characterized by X-ray diffraction (XRD), Raman spectrum, scanning electron microscope (SEM), and transmission electron microscopy (TEM), respectively. Briefly, the size of carbon crystalline (L_c), the content of graphite carbon (I_G/I_All), and the content of regular carbon microcrystals (I_g) in coal-based needle coke were higher than petroleum-based needle coke when the calcinations temperature was below 1500°C. What's more, the calcinations temperature of 1400°C is the characteristic temperature of the transition of carbon microcrystalline. In other words, the coal-based needle coke was easier to graphitization than petroleum-based needle coke.

中文翻译：

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煤基和石油基针状焦微观结构的转变：煅烧温度的影响

针状焦被认为是生产超高功率石墨电极、商业锂离子电池负极材料和特种石墨材料的最重要前体之一。人们普遍认为，针状焦的微观结构对其衍生石墨材料的质量起着关键作用。本工作以四种生针状焦（煤基生针状焦和石油基生针状焦）为原料，研究了煅烧过程中微观结构的变化。针状焦在不同煅烧温度下的微观结构分别通过 X 射线衍射 (XRD)、拉曼光谱、扫描电子显微镜 (SEM) 和透射电子显微镜 (TEM) 进行了详细表征。简言之，碳晶的尺寸（L_c )，当煅烧温度低于1500℃时，煤基针状焦石墨碳含量(I _G /I _All )和规则碳微晶含量(I _g )高于石油基针状焦. 更重要的是，1400°C的煅烧温度是碳微晶转变的特征温度。换句话说，煤基针状焦比石油基针状焦更容易石墨化。