化學氣相沉積製備碳錫奈米複合材料作為鋰離子電池之陽極

Abstract

於本論文中，我們提出一簡單方式製備碳材包覆金屬錫之核殼奈米複 合材料來作為一陽極材料。以二氧化錫作為前驅物，通入乙炔氣體並利用高溫爐管於700 oC 及氬氣作為載流氣體之環境成長；其中長軸為數十微米長度；碳層具有20 – 50 奈米厚度。根據實驗所觀察之結果，提出一氣固相反應的成長機制-"相分離"，藉其嘗試了解其成長過程。在反應過程中，碳材會包覆金屬錫成液滴狀並逐步形成核殼結構，最終發展為完整之一維管狀結構。 電池測試，以碳錫材料作為陽極 (充放電速率為1 C)，經過50 次循環充放電仍有180 mAhg-1。在另一方面，若以二氧化錫作為陽極材料，發現其有嚴重之衰退現象且可逆電容僅剩15 mAhg-1。因此未來希冀藉由改善此複合材料可以提升電極之充放電循環次數。

Here, we present a simple preparation of Sn@C core-shell nanocomposites as stable anode materials. Sn@C anocomposites were synthesized by reacting tin dioxide particles directly with a flowing mixture of cetylene and argon gas at 700 oC. The presence of the hair-like heterostructures is the principal feature of the Sn@C core-shell nanocomposites. The obtained Sn@C nanocomposites were several tens micrometers in length. The carbon shell was about 20 – 50 nm in thickness. Based on the observed results, we propose the “phase segregation” model that may be used to rationalize its growth. The nanocomposites were investigated as a potential anode material for Li-ion batteries. The Sn@C nanocomposite electrode exhibited a cyclic performance and maintained a reversible capacity of approximately 180 mAhg-1 after 50 cycles at 1 C current density. On the other hand, the data of the unprocessed, pure SnO2 particles showed a severe capacity degradation, which occurred within the first 50 cycles and led to a reversible capacity of only 15 mAhg-1 at 1 C current density. We anticipate that further improvement of the new composites may enhance the cyclability of the electrode.