液相反應DPG（熔解偏析石墨）製程之奈米碳管形成機制研究

Study on the mechanism of the formation of carbon nanotubes from DPG（Dissolution Precipitation Graphite） process in the system of liquid phase

李富生(Fu-Sheng Li)

指導教授 ： 李源弘

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.02280

摘要

本研究的目的在於探討系統為液相氣氛時，奈米碳管所形成的微結構分析與機制分析。實驗室DPG(Dissolution Precipitation Graphite)製程製備之人工石墨，會藉由硼元素引發之物理化學效應以及鹽酸氯離子之摻雜效應，引起此粉末結構產生變化，進而導致奈米碳管之生成。並搭配人工石墨粉末之導電性測試，探討其阻抗與由不同氯離子濃度所引起之奈米碳管數量和捲曲方向的關係。
另一方面，經過XRD分析、Rietveld Method精算與掃描式電子顯微鏡分析之後，結果發現，鹽酸酸洗處理過後之人工石墨，其石墨化度有隨著氯離子濃度降低的趨勢，擁有更多奈米尺寸之管狀結構，此研究結果證明硼引發之物理化學效應為奈米碳管生成驅動力之一，且經由氯離子摻雜DPG製程之人工石墨，的確能夠改善其物理性質。若應用在鋰離子二次電池負極材料上，也可藉由不同濃度的氯離子摻雜效應，有效改善負極碳材表面的固態電解質介面（Solid Electrolyte Interphase, SEI）的形成，降低鋰離子二次電池第一次不可逆電容量，以提高電池庫倫效率，進而提升鋰電池之電池效能。

關鍵字

奈米碳管 ； 人工石墨 ； 氯離子摻雜效應 ； 物理化學效應

並列摘要

The purpose in this research is to analyze the micro-structure and mechanism of the carbon nanotubes in the system of liquid surrounding. Our research focused on using DPG (Dissolution Precipitation Graphite) process to produce artificial graphite that dispersed some carbon nanotubes and nano-materials. Furthermore, the boron-triggering mechano-chemical effect, change of microstructure, and hydrochloric acid treatment, are the reasons inducing the formation of the carbon nanotubes. Also, the four-points-probe instrument was used in this research to determine electric conductivity, expecting to discuss the relationship with impedance and the number and the orientation of carbon nanotubes formatted by the different concentrations of chloride ion.
On the other hand, the trend of the decreasing of graphitization degree as increasing chloride ion concentration is observed, which is analyzed by XRD with Rietveld refinement method. It implies that the carbon nanotubes formation has a strong relationship to chloride ion doping. This result could also prove that the mechano-chemical effect and HCl treatment are the driving forces of carbon nanotubes formation. These are the critical keys of the new unusual process.
Then, on the application of the anodic material of the lithium secondary battery, the method to control the forming of SEI, reduce the first irreversible capacity, and improve the battery efficiency was also be find out by pre-treating powder with different concentration of chloride ion.

並列關鍵字

solid electrolyte interface ； lithium ion secondary battery ； carbon nanotube ； artificial graphite ； mechanochemical effect ； Chloride ion doping effect

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