新製程DPG石墨吸附電解質分解之氣體及其提昇鋰離子二次電池性能之研究(Ⅱ)-由高速恒電位儀吸氫量測解析DPG

Abstract

本計畫研究目的是以DPG 製程製備含硼之人工石墨，探討硼引發的物理化學效應及鹽酸酸洗人工石墨後其物理性質的變化，並將人工石墨應用於鋰離子二次電池之負極材料，評估其電池性能表現，最後，以電化學循環伏安法測試人工石墨中氫的含量，探討含氫量與奈米碳管的關係。 經過XRD 分析、Rietveld Method 精算與拉曼光譜分析之後，結果發現，鹽酸酸洗處理過後的人工石墨，擁有更好的結晶性及更高的石墨化度，使得應用在鋰離子二次電池負極材料上的電池性能表現出高電容量、高庫倫效率及長充放電循環次數，BH300 人工石墨有最高電容量505mAh/g，電化學測試方面，循環伏安法測試結果顯示，硼加入量300ppm 至2000ppm 的人工石墨其還原電量較大，可能為大量的奈米碳管含氫量多所致，此結果與 BH300 及BH1000 人工石墨具有高電容量互相印證。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鹽酸酸洗DPG 製程之人工石墨的確能夠改善其物理性質，並在鋰離子二次電池的電池表現上得到最佳的例證。

The material investigated on this study is artificial graphite included boron fabricated by DPG process. The boron-triggering mechanochemical effect and physical properties of artificial graphite cleaned by HCl were studied. And the performance of lithium ion secondary battery using artificial graphite as anodic material was also estimated. At last, the relationship between hydrogen content and carbon nanotube was evaluated by cyclic voltammetry. From the experimental results of XRD analysis、Rietveld Method refinement and Raman spectra analysis, artificial graphite cleaned by HCl owns better crystallization and higher graphitization. These two results increased the battery performance, such as high energy density、high coulomb efficiency and long charge-discharge cycles. For example, BH300 has the highest energy density 505mAh/g. Besides, cyclic voltammetry revealed that the electric flux of BH300 and BH1000 during reduction was much more than other artificial graphite, and more electric flux can be explained that more hydrogen content was resulted from by carbon nanotube. This study proved that HCl cleaning treatment indeed improved the physical properties of artificial graphite. And hydrogen content of carbon nanotube can be evaluated by cyclic voltammetry. For lithium ion secondary battery, artificial graphite is a good candidate for material of cathode.