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  • 學位論文

陣列式奈米碳管-二氧化錳複合電極應用於超級電容器之研究

The Study of Arrayed CNT-MnO2 Composite Electrodes for Supercapacitor Applications

指導教授 : 黃金花
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摘要


本研究在一般與陣列式奈米碳管電極上,沉積二氧化錳製備複合電極,並比較其電化學特性及形貌的差異。一般複合電極由於奈米碳管生長密集導致電解液離子不易擴散進電極內部,造成二氧化錳易聚集在奈米碳管頂部的現象。而陣列式複合電極因奈米碳管陣列之間有一定的間隔,電解液離子容易擴散至電極內部,使二氧化錳較能均勻地沉積在奈米碳管的側壁,進而提升電化學特性。 本研究以黃光微影製程製備成長陣列式奈米碳管所需陣列圖案,接著以微波電漿輔助化學氣相沉積法,在矽基板上生長奈米碳管,經由硝酸處理使奈米碳管具親水性。再以循環伏安法於10 mM過錳酸鉀水溶液中,將二氧化錳沉積在奈米碳管上,沉積掃描速率為100 mV/s,掃描電位在-1~1 V,並改變沉積圈數及陣列式電極之間距,以得到最佳電化學效能。 本實驗使用循環伏安法進行比電容值與長時間穩定性分析,掃描電位與速率範圍分別為0~0.9 V與10~200 mV/s,電解液為2 M硫酸鈉水溶液,再利用掃描式電子顯微鏡與拉曼光譜儀分析複合電極之形貌與結構。實驗發現當奈米碳管陣列之間距為20 m 時,二氧化錳可均勻地沉積在奈米碳管側壁以及頂部,因此具有最佳電化學特性。在10 mV/s 掃描速率下,一般與陣列式複合電極之最佳面積比電容值分別為14.22與332.85 mF/cm2。相較於一般複合電極,陣列式複合電極之比電容值提升了約23倍,且其在經過1000次長時間掃描後的電容維持率亦高達96 %,顯示陣列式奈米碳管/二氧化錳複合電極為一非常具有潛力之超級電容器電極材料。

並列摘要


In this thesis study, it was to investigate and compare the differences of the morphology and electrochemical properties of the carbon nanotubes/MnO2 nanocomposite electrodes with normal- and pattern-type carbon nanotubes (CNTs). Owing to the highly dense character of normal-type CNTs, which prevents the electrolyte ions from penetrating into the inside of electrodes, MnO2 tend to aggregate onto the top of the CNTs. In contrast, the pitches in pattern-type CNTs can provide enough space for electrolyte ions to diffuse into electrodes, which allows MnO2 being uniformly electrodeposited onto the side area of the CNTs. Thus, pattern-type nanocomposite electrodes are expected to exhibit improved electrochemical properties. The CNTs were grown on normal and patterned Si substrates by microwave plasma-enhanced chemical vapor deposition, followed by a hydrophilic treatment in HNO3 solution. Then, the CNT electrodes were placed in 10 mM KMnO4 to deposit MnO2 onto the CNTs by cyclic voltammetry. The potential range was applied between -1 and 1 V and the depositing scan rate was 100 mV/s. By changing the deposition cycle number and the separation between arrayed CNTs, optimization of the nanocomposite electrodes has been achieved. The areal specific capacitance and long time stability of all nanocomposite electrodes were analyzed using cyclic voltammetry. The electrolyte was 2 M Na2SO4. The potential range was applied between 0 and 0.9 V and the scan rate was applied between 10 and 200 mV/s. The composition structure and morphology of the nanocomposite electrodes were characterized by scanning electron microscopy and Raman spectroscopy. It was found MnO2 could be uniformly deposited onto the top and sidewalls of the pattern-type CNTs with 20 m pitches, and the resulting nanocomposite electrode exhibited the best electrochemical properties. The optimized areal specific capacitances of normal and pattern-type nanocomposite electrodes, at 10 mV/s scan rate, were 14.22 and 332.85 mF/cm2 respectively; the latter is about 23 times of the former. In addition, the best pattern-type nanocomposite electrode maintained 96 % of the initial capacitance at 1,000th cycle, indicating its potential electrode material application in supercapacitors.

並列關鍵字

無資料

參考文獻


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