鋰電池碳-矽複合負極材料與含石墨鍍銀導電膠研究

Carbon-Coated Silicon Nano-Composites as Negative Electrodes for Lithium Batteries and Electrically Conductive Adhesives Containing Ag-Plated Graphite Particles

闕帝強(Ti-Chiang Chueh)

指導教授 ： 顏溪成

國立臺灣大學/工學院/化學工程學研究所/博士(2014年)

https://doi.org/10.6342/NTU.2014.03033

摘要

本研究分為兩大部分，第一部分是碳包覆矽複合材料在鋰離子電池負極上的研究，第二部分是含有石墨鍍銀粒子的導電膠研究。首先嘗試製作碳包覆矽的奈米複合材料，並將之應用於鋰離子電池的負極上的研究。將矽粒子與不同的碳前驅物所組成的混合溶液置於超音波震盪槽中混合均勻，接著對此混和溶液分別在600 – 1000 oC的溫度下進行熱處理，以獲得表面有均勻碳層包覆的矽粉體。透過改變實驗相關的變因和參數，如熱裂解包覆溫度、矽粉體的粒徑、碳前驅物與矽的比例、熱處理時間等，找出實驗最佳的參數，並將不同條件所製成的碳矽複合材料製作成半電池進行充放電測試。實驗結果顯示，選用蜂蜜做為碳前驅物，熱處理溫度1000 oC、時間2小時、碳前驅物與矽的比例為50 : 1，有最佳的電池循環壽命；以此材料做成的半電池，經51次的充放電測試後，仍有高達2355 mAh/g的電容量，與首次放電3006 mAh/g相比，平均每圈僅有0.42%的電容量損耗，此結果遠優於純石墨電極的充放電測試結果。除此之外，此碳塗佈矽複合材料所製程的半電池也與純矽所組成的半電池進行充放電測試比較，可發現經過熱處理碳包覆矽的材料，其電池表現較純矽電極有明顯的改善。
本論文的第二部分為含石墨鍍銀粒子的導電膠研究。吾人提出一套有別於傳統(透過氯化亞錫敏化與氯化鈀活化程序)無電鍍的的銀自身活化的無電鍍法，結果顯示經由此方法所製得之石墨鍍銀導電顆粒，表面都有一層均勻的銀覆蓋其上。進一步量測此石墨鍍銀粉末與環氧樹脂所製成的導電膠之電阻係數，可得到當填充的石墨鍍銀粉體60 wt %時，擁有5.16 × 10-4 Ω-cm的電組，經換算後銀的含量僅有56.6 wt %，低於文獻和商用的導電銀膠銀含量。

關鍵字

鋰離子電池 ； 矽 ； 碳矽複合材料 ； 蜂蜜 ； 石墨鍍銀 ； 導電膠 ； 銀自身活化

並列摘要

This thesis study contains two parts. The first part is carbon-coated silicon nano-composites as negative electrodes for lithium-ion batteries. The second part is electrically conductive adhesives (ECAs) containing Ag-plated graphite particles.
An effective method to produce carbon-coated silicon nano-composites as a high-capacity anode material for rechargeable lithium-ion batteries has been investigated. Initially, silicon particles mixed in different carbon precursor solutions via ultrasonication were prepared by thermal treatment in inert gas at elevated temperature (600 - 1000 oC) to form a homogeneous carbon-coated layer onto the surface of the silicon nanoparticles. The effects of the processing temperature, the duration of thermal treatment, silicon particle size, and the mass ratio of carbon precursor to silicon were investigated in detail. All of these parameters significantly influence the cyclic charge/discharge performance of the carbon-coated Si nanocomposites. Carbon-coated Si nano-composites by using honey as carbon precursor in Argon gas at 1000 oC showed the better cycling performance, with a capacity loss of less than 0.42 % per cycle and retaining a specific capacity of 2355 mAh/g beyond 51 cycles, which is much better than the graphite anode. Furthermore, the capacity fading and lithiation mechanisms of silicon and carbon-coated silicon particles also been measured and studied by cycling tests. The dimensional stability of the Si nanoparticles provided by the carbon nano-coating enhances the electric contact of silicon particles and it seems to be the leading reason for this better improved electrochemical performance.
Besides, the conductivities of electrically conductive adhesives (ECAs) containing silver-coated graphite particles by self-activated deposition has been investigated. A novel silver self-activated electroless deposition on graphite designed as conductive filler were employed, and a uniform silver coating with minimal agglomeration on graphite surface was obtained. Furthermore, the electrical resistivity of electrical conductive adhesives containing silver-plated graphite powders have also been investigated in this study. The best result of the electrical resistivity of epoxy-based conductive adhesives obtained is 5.16 × 10-4 Ω-cm for 60 wt% of silver-plated graphite powders. The weight percentage of silver in this epoxy-based adhesive is reduced to 56.6 wt%, which is much less than that of the regular silver conductive adhesives.

並列關鍵字

Lithium-ion battery ； Silicon ； carbon-coated Si materials ； honey ； electrically conductive adhesives ； silver self-activated electroless deposition

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