不同維度矽/碳奈米複合材料的製備與鋰離子電池負極材料應用

鋰離子二次電池在我們日常生活中扮演了極重要的角色，應用範圍小至手機、平板、筆電的電池大至電動車的電池，都能發現其蹤影，所以如何提升鋰離子電池的儲電量，將成為現今的一大課題；矽作為地殼上僅次於氧含量第二多的元素，擁有無毒性及前處理容易等優點，更重要的是其理論電容量為~4200 mAh/g，相對於市售鋰電池碳負極材料理論電容值372 mAh/g，電量高出十倍，是具有相當優勢的負極材料之一，但在充放電反應時，矽的體積會產生劇烈的膨脹導致顆粒碎裂，造成電容值的急速下降，而此問題將成為矽成為商業化產品的一大阻礙。本研究將成功地使用不同維度的碳材，分別製備出一維(奈米碳管)、二維(還原氧化石墨烯)和三維(規則中孔洞碳材)的矽-碳複合材料，做為負極材料應用於鋰離子電池上，利用不同種類的碳之結構特性，減緩充放電過程中所帶來體積過度膨脹的問題且避免奈米矽顆粒的聚集，並經由充放電儀測試，得到不同維度下矽-碳複合材料之最佳比例，最後使用其他電化學分析去加以驗證；不同維度：一維、二維及三維之最佳比例的複合材料，經100 mAh/g充放電速率下掃描一百圈下，其電容值分別為~800 mAh/g、~1000 mAh/g及~1300 mAh/g，且庫倫效率皆達到97%以上，表示本研究的複合材料能在長圈數的充放電下，維持材料的結構不受破壞以及電化學反應的穩定性，而未來將可透過此方法，改善在充放電過程中體積膨脹率大的材料上，例如：錫、銻、鎂、鋁等，用以提升鋰離子電池的效能以及增進電容量。

關鍵字

鋰離子電池；負極材料；奈米矽；奈米碳管；還原氧化石墨烯；規則中孔洞碳材

並列摘要

Lithium ion batteries (LIBs) play an important role in our daily life. It has been used for cell phone, ipad, laptop and battery electric vehicle. It is one of the richest topics to improve the battery performance in nowadays. Silicon is present in the earth’s crust at 27.7 % of the total and, after oxygen, is the second most abundant element. In addition, Silicon has been widely used as the anode material for lithium ion batteries (LIBs) because of the huge theoretical capacity (~4200 mAh/g) compared with commercial carbon material (~372 mAh/g) and relatively low discharge potential (~0.5V VS. Li/Li+). However, the large volume expansion (~ 400%) after charge-discharge processes hampers the application of silicon to LIBs. In this study, we have synthesized successfully that the combination of Si with different dimensional carbon materials including carbon nanotubes (1D), graphenes (2D), and mesoporous carbons (3D) can minimize the volume expansion, resulting in the enhancement of electrochemical performance of silicon-based electrodes. After 100 cycles, the capacity of 1D, 2D and 3D nanocomposites are ~800 mAh/g, ~1000 mAh/g and ~1300 mAh/g respectively. The coulomb efficiency is above 97% remarkably. It shows our different dimensional carbon materials can be maintained structure after charge-discharge and excellent electrochemical stability. In the future, it can provide the method to improve materials which have the large volume expansion after charge-discharge processes, for example Sn, Sb, Mg and Al.

並列關鍵字

Lithium ion battery ； anode materials ； Silicon ； Carbon nanotubes ； Graphene ； Mesoporous carbons

參考文獻

1. Armand, M.; Tarascon, J. M., Building better batteries. Nature 2008, 451 (7179), 652-657.

2. Tarascon, J. M.; Armand, M., Issues and challenges facing rechargeable lithium batteries. Nature 2001, 414 (6861), 359-367.

4. Etacheri, V.; Marom, R.; Elazari, R.; Salitra, G.; Aurbach, D., Challenges in the development of advanced Li-ion batteries: a review. Energy & Environmental Science 2011, 4 (9), 3243-3262.

6. Chou, S.-L.; Pan, Y.; Wang, J.-Z.; Liu, H.-K.; Dou, S.-X., Small things make a big difference: binder effects on the performance of Li and Na batteries. Physical Chemistry Chemical Physics 2014, 16 (38), 20347-20359.

9. Wu, H.; Cui, Y., Designing nanostructured Si anodes for high energy lithium ion batteries. Nano Today 2012, 7 (5), 414-429.

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不同維度矽/碳奈米複合材料的製備與鋰離子電池負極材料應用

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