銅與銅化合物奈米材料之形狀控制、性質分析與鋰離子電池的應用

Copper and Copper Compound Nanomaterials: Shape Control, Properties Analysis, and Lithium-Ion Battery Applications

楊鴻傑(Hong-Jie Yang)

指導教授 ： 段興宇

國立清華大學/工學院/化學工程學系/博士(2014年)

摘要

在此論文中，我們的研究主要分為三個主題。
第一 : 銅奈米材料形狀控制與性質分析。我們使用氯化亞銅為前驅物，經由添加不同表面活性劑可分別於溶液相中合成出銅奈米線與銅奈米立方體，經由電子顯微鏡與紫外光-可見光吸收光譜來觀察奈米線成長過程並進一步提出成長機制，銅奈米線的電性與銅奈米線基板的表面增強拉曼光譜亦被分析。此外合成出的銅奈米立方體粒均分布十分均一(標準偏差為3.87 %)，根據穿透式電子顯微鏡和小角度X光散射儀分析結果，這些銅奈米立方體傾向於自我組裝成二維或三維的菱形結構，我們亦使用銅奈米立方體為單元組件，去製作成銅薄膜，更進一步分析其電性。
第二 : 碲化銅奈米材料形狀控制與性質分析。實心和空心的碲化銅奈米粒子可經由控制注射碲前驅物溶液的時間而分別合成出來，這兩種形狀的碲化銅奈米粒子由於在價帶上多餘的電洞(銅缺陷)，造成於紅外光區有明顯的吸收峰(局部表面電漿共振效應)，實心的碲化銅奈米粒子吸收峰波長位於1150奈米且莫耳消光系數為2.6 × 107 M−1 cm−1，空心的碲化銅奈米粒子吸收峰波長位於1200奈米且莫耳消光系數為2.7 × 107 M−1 cm−1。此外我們還可以經由氧化還原的方式去控制碲化銅奈米粒子結構中銅缺陷的程度，達到控制其表面電漿共振峰的強度以及位置。
第三 : 矽(鍺)/銅自支撐奈米線織布於鋰離子電池的應用。使用高理論電容的矽(鍺)奈米線與高電導率的銅奈米線製作的自支撐奈米線織物電極可直接應用於鋰離子電池中的負極，這種特殊的電極結構擁有許多優點，與傳統電極比較其重量較輕，銅本身的高導電率和一維的奈米結構可方便電子傳輸，奈米線織布間的空隙可提供空間給予矽(鍺)奈米線於鋰化與去鋰化過程時產生的體積膨脹與壓縮。此外我們亦有進一步探討，製作奈米線織物電極時所使用的銅奈米線比例以及燒結溫度對電化學效率的影響。

關鍵字

銅奈米材料 ； 碲化銅 ； 鋰離子電池 ； 自組裝 ； 表面電漿共振

並列摘要

In this dissertation, we have three themes.
First : Shape control and properties analysis of Cu nanomaterials. Cu nanowires and Cu nanocubes can be synthesized in solution phase by using CuCl as precursors with right surface ligands. Electron microscopy and UV-vis spectra were used to track the growth process of Cu nanowire and further proposed possible growth mechanism. In addition, the electrical property of single Cu nanowire and surface-enhanced Raman spectroscopy of Cu nanowire substrate had studied. The as-synthesized Cu nanocubes have a slightly truncated with an average edge length of 75.7 nm and a standard deviation of 3.87 %. Electron microscopy and Small-angle X-ray scattering characterizations were used to identify the self-assembled structures of Cu nanocubes. Based on analysis results, Cu nanocubes prefer self-assemble into 2D or 3D rhombohedral structure. Cu thin films composed of monodisperse Cu nanocubes were made by tilting the substrate in the Cu nanocube solution and controlled evaporation rate of toluene. Furthermore, the electrical properties of Cu thin films were also studied before and after thermal annealing.
Second : Shape control and properties analysis of Cu2−xTe nanomaterials. Solid and hollow structures of Cu2−xTe nanocrystals can be synthesized by injection of a Te-TOP solution at different injection time. Both types of Cu2−xTe nanostructures exhibit an intense absorption peak (localized surface plasmon resonance, LSPR) in the NIR region, arising from excess holes in the valence band, with high molar extinction coefficients of 2.6 × 107 M−1 cm−1 at 1150 nm and 2.7 × 107 M−1 cm−1 at 1200 nm for the solid-type and hollow-type Cu2−xTe nanostructures, respectively. The LSPs band of the Cu2−xTe nanostructures can be fine tuned by post processing via oxidation and reduction methods (controlling their degree of copper deficiency).
Third : Si(Ge)/Cu free standing nanowire fabric for lithium ion battery anodes. Si (Ge) based free standing nanowire fabric electrodes which are made by Si (Ge) nanowires with high theoretical capacity and Cu nanowires with high electric conductivity can be directly used as lithium ion battery anode electrodes. These special electrode structure have advantages of lighter weight than conventional electrodes fabricated by slurry process, good electron transfer offered by the Cu and the one dimensional nanostructure, and the space among the nanowires accommodating the volume contraction of Si (Ge) nanowires during alloying and dealloying process. In addition, the effect of the weight percentage of Cu nanowire and annealing temperature on the electrochemical performance had investigated.

並列關鍵字

copper nanomaterials ； copper telluride ； Lithium ion battery ； self assembly ； surface plasmon resonance

參考文獻

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