天然石墨与人造石墨的鉴别方法

2025-03-26

天然石墨阳极材料由自然鳞片晶体石墨制成，经过研磨、球形化、分级、纯化和表面处理等工艺，其高结晶度是自然形成的。而人工石墨阳极材料是通过在一定温度下煅烧石油焦、针状焦、沥青焦等易于石墨化的碳材料，然后经过破碎、分级、高温石墨化系统而成，其高结晶度是通过高温石墨化形成的。由于原材料和制备工艺的本质差异，二者的微观结构、晶体结构、电化学性能和加工性能明显不同。

在微观结构方面，天然石墨是层状的。天然石墨的扫描电子显微镜（SEM）图像保留了层状结构，层状结构之间有很多间隙。在高温石墨化过程中，晶体结构根据ABAB结构进行重新排列，进行聚合收缩，其内部密度没有间隙。

X射线衍射

From the perspective of crystal structure, the natural graphite anode material has high crystallinity. In the XRD pattern, its (002) crystal plane diffraction peak Angle is higher, the lamellar structure is complete, the layer spacing is small, and the orientation (I002/I110) is obvious. From the diffraction peak position of (101) crystal plane corresponding to 43-45 degree and the diffraction peak position of (012) crystal plane corresponding to 46-47 degree, It can be seen that natural graphite has obvious 2H phase and 3R phase, while artificial graphite only has 2H phase. The XRD patterns of hexagonal graphite (2H) and rhombohedral graphite (3R) are as follows:

拉曼光谱

For natural graphite and artificial graphite without graphitization treatment, in addition to the SEM profile, XRD crystal structure diagram and its parameters to distinguish, Raman spectrum test disorder ID/IG is also an effective method to distinguish these two types of graphite. The disorder degree ID/IG of natural spherical graphite is generally 0.4~0.85, the disorder degree ID/IG of natural graphite coated on the surface without graphitization is generally 0.9~1.6, and the disorder degree ID/IG of new modified natural graphite without graphitization is generally 0.2~0.6. The disorder degree OF artificial graphite ID/IG is generally 0.04~0.34. On the whole, the disorder degree ID/IG of natural graphite anode material without high temperature graphitization is larger than that of artificial graphite anode material. The disorder degree ID/IG of the graphitized natural graphite coated on the surface is generally 0.17~0.36, and that of the artificial graphite is generally 0.04~0.34. The disorder degree ID/IG of the graphitized natural graphite and the artificial graphite are in intersection, and Raman test is not an effective method.

结果判断

1. 没有高温（2400-3300℃）石墨化处理的天然石墨负极材料与人造石墨负极材料的比较

(1) SEM横截面：未经过高温石墨化处理的天然石墨负极材料的SEM横截面中，片状结构之间存在间隙，而人造石墨负极材料的SEM横截面则致密无缝。

(2) XRD：未经过高温石墨化处理的天然石墨负极材料的XRD图谱中明显存在2H相和3R相，而人造石墨负极材料的XRD图谱中仅存在2H相。

(3) ID/IG：未经过高温石墨化处理的表面涂层天然石墨负极材料的无序ID/IG一般在0.9~1.6之间，而人造石墨的无序ID/IG一般在0.04~0.34之间。

2. 高温（2400-3300℃）石墨化的天然石墨负极材料与人造石墨负极材料的比较

(1) SEM横截面：经过高温石墨化处理的纯天然石墨负极材料的SEM横截面中，片状结构之间存在间隙，而纯人造石墨负极材料的SEM横截面则结构致密且没有间隙，且经过高温石墨化处理。复合石墨负极材料的SEM横截面视图显示，天然石墨片状结构与人造石墨致密无缝结构之间的空隙共存。