- 學位論文
以田口法最佳化多孔矽奈米粉末合成參數以改善鋰離子電池陽極材料充放電性質
Using Taguchi method to optimize the synthesis processes of porous silicon nanoparticles as anode materials for lithium ion batteries.
摘要
能量存儲系統已經成為用於解決石油危機的關鍵技術，而鋰離子電池具有較高的理論能量和功率密度，因此為相當有發展潛力的能量存儲系統之一。其中理離子電池中的矽基負極材料因為其高理論電容量而被廣泛研究，但因其充放電過程中會有300 %體積膨脹，造成電池循環壽命不佳。 本研究使用田口方法來使多孔二氧化矽奈米顆粒合成參數最佳化，以提高在鋰離子電池的循環壽命性能。其中二氧化矽合成中，存在CTACl/TEOS = 0.058的最佳比例以形成奈米顆粒的孔隙。且存在最佳TOEA/TEA = 0.25，以形成最小的顆粒。在鎂還原的製程中，對於循環壽命性能最好的參數是：外壓= 0.75 torr、Mg/SiO2 = 4、溫度= 625 oC、時間= 6小時。 將兩個最佳參數結合後，得到具有高表面積(394 m2/g)的矽奈米粉末以及decay百分比為40 %的電性表現。並將二氧化矽和成田口法中比表面積最大(L5)、中間(L2)以及最小(L8)分別利用L5參數還原作電性比較。最終我們得出結論，有較高孔隙率以及孔體積的奈米顆粒對於循環壽命表現的影響小於顆粒大小對電性表現的影響。
並列摘要
Energy storage system has become a critical technology for solving the oil crisis, and the lithium ion battery is one of the promising energy storage systems owing to the high theoretical energy and power density. Moreover, Silicon – based anode materials for lithium ion battery have been widely studied in recent years because the high specific capacities of silicon. This study uses Taguchi method to optimize the synthesis processes of porous silicon nanoparticles to improve the cycle life performance in lithium ion batteries. In the processes of SiO2 synthesis, there is a best ratio of CTACl / TEOS, 0.058, to form pores in nanoparticles, and a ratio of TOEA / TEA to form minimum particles. In the processes of Mg reduction, the best parameters for cycle life performance are: Outer pressure = 0.75 torr, Mg / SiO2 = 4, temperature = 625 oC, time = 6 hr. We conclude that the effect of porosity with large pore volume is less effective than that of particle size on the cycle life performance.