DPG人工石墨粉末衍生物分析研究

Abstract

本實驗室製作的人工石墨粉，應用在鋰離子二次電池陽極材料方面有相當好的電容量，DPG人工石墨電容量高過理論值372mAh/g，達到400mAh/g以上，但相對的電池不可逆也高達30%以上。在使用HBr酸洗處理DPG人工石墨粉時，我們於XRD發現不同於石墨的繞射峰。

本實驗主要在於討論人工石墨粉中產生不同於石墨衍生物的成分以及其含量，以及探討使用不同濃度的HCl或者HBr對人工石墨粉進行酸洗處理後衍生物成份受到如何的影響。我們將使用SEM(scanning electron microscopy)來觀測外觀上的變化，以及使用XRD(X-ray diffraction)和 EDX(energy dispersive spectrometer)來對DPG人工石墨粉進行定性分析，判斷衍生物可能的結構，接著使用 Rietveld Method 來對其可能結構進行含量的精算。 經由實驗結果發現，DPG人工石墨粉中至少含有Hexagonal graphite、Orthorhombic Carbon、Iron Oxide(Fe2O3)這三種成分，並且隨著我們使用不同濃度酸的處理其成分也會隨之變化，我們發現，使用高濃度的HCl或者高濃度的HBr去進行酸洗過後，所得到的成分含量中，Hexagonal Graphite 在 DPG粉末中所佔的比例增加而Orthorhombic Carbon 所佔的比例減少，這也代表著Orthorhombic Carbon 由於其結晶性不如石墨，而遭到HBr的腐蝕。

The DPG powders manufactured in the experiment was applied to the anode material for lithium ion secondary battery, and the capacity of the battery was good. The reversible capacity of DPG powders was over 400 mA/g , even higher than the theoretical value 372mAh/g. However, the irreversibility of the battery reached 30%.In the HBr rinsed DPG powders, we found one different diffraction peak in the XRD pattern.

The conception of experiments was finding out the possible structure of the derivatives. At the same time, we calculated the content of the derivative in the DPG powders. Finally, we compared the results of the DPG powders which was manufactured with the different concentration of HBr we used SEM(scanning electron microscopy) to observe the changes on the surface, and used XRD(X-ray diffraction) and EDX(energy dispersive spectrometer) to carry out qualitative analysis, and then decided the possible structure of the derivatives. In the end, we used Rietveld Method to estimate the content of the different derivatives in the DPG powders. Results from the experiment indicated that there were at least three different kinds of components in the DPG powders: Hexagonal Graphite, Orthorhombic Carbon, Iron Oxide(Fe2O3). Meanwhile, the content of the three kinds of the derivatives changed with the concentration of HBr and used. We found that content of the Hexagonal Graphite increased with the concentration of HBr we used. However, the content of the Orthorhombic Carbon decreased with the concentration of HBr we used. It indicated that the Orthorhombic Carbon was more reactive with HBr than the Hexagonal Graphite for the poor crystallinity.