聚丙烯腈基在鋰離子電池矽碳負極複合材料上之應用

Applications of PAN on Si/C Composite Anode Material for Lithium Ion Battery

許銘麟(Ming-lin Hsu)

指導教授 ： 吳乃立

國立臺灣大學/工學院/化學工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.02297

摘要

在過去的十年中，鋰離子電池已在手機等電子零件的市場中成為主流。目前，商業上用的負極碳基底材料具有低工作電位、高可逆性以及低成本等優點，然而，碳基底負極材料的理論比電容量低(372 mAh/g)。在替代的材料之中，矽材料因為具有高的比電容量低(~3500mAh/g)而受到關注，但是，低導電度的特性跟鋰化時造成的劇烈體積膨脹收縮阻礙了矽負極材料在商業化的應用。

在本本論文中，我們以開發矽主體的鋰離子二次電池負極材料為目的。根據前人的研究，我們可以知道矽碳複合材料可以改善上述矽應用在鋰離子電池所遭遇到的問題。我們以溶液塗佈法在矽碳複合材料上批覆一層聚丙烯腈薄膜。在批覆聚丙烯腈之後，比電容量跟循環性能皆有改善。

此外，我們在原有的電解液中加入氟代碳酸乙烯酯以改善循環性能。結果顯示，跟未在電解液中加入氟代碳酸乙烯酯的數據比較，總體的庫倫效率跟循環後的比電容量都有增加。

最後，本研究也利用預置鋰遷入法來改善第一圈的庫倫效率，實驗結果顯示，第一圈庫倫效率確實提升了，因此它未來十分有潛力被實際應用在鋰離子電池的製程中。

關鍵字

鋰離子電池 ； 矽 ； 聚丙烯腈 ； 氟代碳酸乙烯酯

並列摘要

Lithium ion batteries have been dominating the market for mobile electronic devices for decades. Commercial anode graphite material has advantage of low working voltage, high reversibility and low cost. However, the major disadvantage is its low theoretical capacity of 372 mAh/g. Silicon is the most promising alternative material for its high theoretical specific capacity(~3500mAh/g) and low alloying potential versus Li. However, low electronic conductivity and dramatic volume expansion upon lithiation hinder the commercialization of Si-based anode.

In this study, the main objective is to find new Si-based anode materials for lithium-ion battery. According to previous studies, the Si/C composites have overcome some cycle-life problems of silicon. We use solution coating method to coat porous Si/C composites with a thin Polyacrylonitrile (PAN) layer. Capacities and cycle performance were enhanced after PAN-coating.

Moreover, FEC was added into EC/ EMC electrolyte to enhance cycle performance. The results showed overall coulombic efficiency and capacity after cycling were increased compared to previous PAN-coated Si/C composites electrode.

Finally, the pre-lithiation approach was adopted to enhance the coulombic efficiency in the first cycle. First cycle coulombic efficiency was increased after pre-lithiation approach. This result indicated that this approach is effective and has the potential for practical use.

並列關鍵字

Lithium-ion batteries ； silicon ； poly-acrylontrile ； fluoroethylene carbonate

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