原子層沈積二氧化鈦於奈米碳管作為免黏著劑之超級電容電極

Atomic layer deposition of TiO2 on carbon nanotubes as binder-free supercapacitor electrodes.

吳易珉(Wu, I Ming)

指導教授 ： 徐文光

國立清華大學/工學院/材料科學工程學系/碩士(2015年)

https://doi.org/10.6843/NTHU.2015.00194

摘要

現今超級電容的電極研究對象多以金屬氧化物/氮化物為主，因此類材料能提供擬電容效應。其中，二氧化鈦的原料較易取得、對環境負擔小和良好的表面化學活性，具備作為超級電容電極的潛力；但二氧化鈦導電度較差，會影響電解液中電荷的傳遞；此外，過去研究奈米結構之粉體，多需要與黏著劑混合製成電極，同樣會降低導電度以及影響離子滲透能力。因此，本研究嘗試加入奈米碳管，同時以原子層沈積製成鎳網/奈米碳管/二氧化鈦之層狀結構。首先，將酸化後的奈米碳管以電泳沈積至鎳網，接著以原子層沈積數奈米厚度之二氧化於奈米碳管表面。電極的形貌構造與表面組成透過X光繞射儀、拉曼光譜儀、X光光電子能譜儀、能量散射光譜儀、場發射掃描式電子顯微鏡和穿透式電子顯微鏡得到資訊；電極的電容特性藉由電化學工作站分析，得知其比電容、倍率性能、充放電循環壽命及系統阻抗。本研究顯示，酸化碳管的結構和表面官能基利於二氧化鈦沈積，提升二氧化鈦的利用率；且碳管提供電子及離子的傳輸途徑，降低電荷交換的阻抗，經過原子層沈積50層/100層二氧化鈦的電極，比電容值分別可達到564 F/g 及432 F/g。

關鍵字

超級電容 ； 原子層沈積 ； 二氧化鈦 ； 奈米碳管 ； 比電容

並列摘要

Recent study on supercapacitor electrodes focuses on metal oxide/nitride which shows high pseudo-capacitance. Titanium oxide (TiO2) has a potential to be a candidate, because of low production cost, nontoxicity and well electrochemical activity on surfaces. However, most metal oxide are made in powder form, mixing with binder as an electrode, which decreases in conductivity and ionic accessibility of electrode. In this study, carbon nanotubes (CNTs) are introduced to improve above problems. First, nitric acidized CNTs are electrophoretically deposited on nickel mesh and TiO2 is coated onto CNTs following via atomic layer deposition(ALD). The laminar structures(Ni/CNT/TiO2) are characterized by X-ray diffraction (XRD), Raman measurement, Energy dispersive spectrometer(EDS), field emission scanning electron microscopy (FE-SEM) and transition electron microscopy (TEM) . The electrochemical properties of electrode, including capacitance, rate capability, and charge-discharge cycle, are studied by cyclic voltammetry (CV) in Autolab. Result demonstrate that mesoporous structure of carbon nanotubes provide conductive network for charge transport. Specific capacitance reaches 564 F/g and 432 F/g in alkaline solution at scan rate of 10 mV/s for grown using 50 and 100 cycles ALD, respectively.

並列關鍵字

supercapacitors ； atomic layer deposition ； titanium dioxide ； carbon nanotubes ； specific capacitance

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