Enhancement of CNT Supercapacitors by Electrophoretic Deposition and Air Oxidation of CNTs
王籸富、葉競榮
E-mail: 9707279@mail.dyu.edu.tw
ABSTRACT
There are several advantages of conventional capacitors, for example, refreshing and discharging quickly, high power density and long cycle life, etc., but they suffer from a low energy density. With a hope to overcome this shortcoming, the idea of supercapacitors was created, however, up to this time, it still has many problems to be solved, to name just a few, aging and modest energy density.
In this research, these are two of the important topics we worked on. In the past, we grew up carbon nanotubes on graphite electrodes directly using nickel as catalyst, but their performance ages after some ten cycles. This research made use of electrophoresis deposition to deposit carbon nanotubes on graphite electrodes, then the carbon-nanotube-deposited graphite
electrode was heated to over 500℃ in air, in order to improve the aging problem and to increase the energy density . The purpose of this oxidation process was trying to change the structure of the deposited carbon nanotubes and to increase the roughness of their surfaces with a hope to increase the capacitance of the designed supercapacitors. We found ,at 600℃, the best results can be achieved. The electrochemical behavior of the designed supercapacitors was analyzed with a three-electrode cyclic voltammetry (CV) system. By the electrophoresis deposition, carbon nanotubes formed the interlacing maneuver of small hole structures. In addition to the higher surface area provided by carbon nanotubes themselves, these small holes can also let charged particles get in and thus increase the capacitances of the designed supercapacitors. The electrophoresis of carbon nanotubes was made possible by adding into the suspension as electrolyte for EPD. However, magnesium ion may cause the deposited carbon nanotubes to peel off from the graphite electrode in the sulfuric acid electrolyte. Hence after the electrophoresis, magnesium ions were removed chemically or by a second oxidation process. With all these efforts, the capacitance of the supercapacitors increased and the aging problem had been improved significantly.
Keywords : carbon nanotube ; supercapacitor ; aging ; electrophoretic deposition Table of Contents
封面內頁 簽名頁 授權書．．．．．．．．．．．．．．．．．．．．．．．．． iii 中文摘要．．．．．．．．．．．．
．．．．．．．．．．．． iv 英文摘要．．．．．．．．．．．．．．．．．．．．．．．． v 誌謝．．．．．．．．．
．．．．．．．．．．．．．．．．． vi 目錄．．．．．．．．．．．．．．．．．．．．．．．．．． vii 圖目錄．．
．．．．．．．．．．．．．．．．．．．．．．． x 表目錄．．．．．．．．．．．．．．．．．．．．．．．．．
xiii 第一章 序論 1.1前言．．．．．．．．．．．．．．．．．．． ．．1 1.2研究目的．．．．．．．．．．．．．．．
．． ．．3 第二章 文獻回顧 2.1奈米碳管簡介．．．．．．．．．．．．．．．．．5 2.2奈米碳管特性．．．．．．．．
．．．．．．． ．．5 2.2.1奈米碳管的電性．．．．．．．．．．．．．5 2.2.2奈米碳管的機械特性．．．．．．．．．
．．8 2.2.3熱穩定性．．．．．．．．．．．．．．． 10 2.2.4熱傳導性．．．．．．．．．．．．．．． 10 2.3奈米碳管 的運用．．．．．．．．．．．．．． ． 11 2.3.1場發射平面顯示器．．．．．．．．．．． 11 2.3.2超微細化學偵測器．
．．．．．．．．．． 11 2.3.3微探針．．．．．．．．．．．．．．．． 12 2.3.4奈米級電晶體．．．．．．．．．．．
．． 12 2.3.5儲氫材料．．．．．．．．．．．．．．． 13 2.3.6奈米生化．．．．．．．．．．．．．．． 13 2.3.7強化 複合材料之添加劑．．．．．．．．． 14 2.4電泳沉積法．．．．．．．．．．．．．．．．． 14 2.4.1電泳沉積法的發展 與優勢．．．．．．．． 14 2.4.2電泳沉積發的原理．．．．．．．．．．． 16 2.4.3電泳溶液裝置．．．．．．．．．．
．．． 17 2.4.4電泳沉積法運用於奈米碳管．．．．．．． 19 2.5電化學原理．．．．．．．．．．．．．．．．． 20 2.5.1電化學反應系統．．．．．．．．．．．． 21 2.5.2循環伏安法．．．．．．．．．．．．．． 24 2.6電化學電容器．
．．．．．．．．．．．．．．． 25 2.6.1電化學電容器分類．．．．．．．．．．． 26 第三章 實驗方法與設備 3.1實驗 藥品．．．．．．．．．．．．．．．．．． 29 3.2實驗儀器．．．．．．．．．．．．．．．．．． 30 3.3實驗步驟．
．．．．．．．．．．．．．．．．． 32 3.3.1石墨電極製備及清洗．．．．．．．．．． 32 3.3.2電泳沉積製程．．．．
．．．．．．．．． 33 3.4電化學電容器的裝置．．．．．．．．．．．．． 36 3.4.1可逆性實驗．．．．．．．．．．．
．．． 36 3.4.2老劣化測試．．．．．．．．．．．．．．．37 3.5材料分析與鑑定．．．．．．．．．．．．．．．．37 3.5.1掃描式電子顯微鏡．．．．．．．．．．．．38 3.5.2高解析穿透式電子顯微鏡．．．．．．．．．38 第四章 實驗結 果與討論 4.1經電泳沉積及高溫燒結之表面型態．．．．．．． 41 4.1.1電泳沉積時間與厚度關係．．．．．．．．． 43
4.1.2電泳沉積燒結效果的評估．．．．．．．．． 45 4.2未燒結與燒結後的成分分析．．．．．．．．．． 47 4.3以奈米 碳管披覆於石墨材料之電化學特性．．．． 53 4.3.1石墨電極之循環伏安行為．．．．．．．．． 53 4.3.2在氫氣環境下燒 結奈米碳管之循環伏安行 為．．．．．．．．．．．．．．．．．． 55 4.3.3在空氣中燒結500℃奈米碳管之循環伏安行為
．．．．．．．．．．．．．．．．．．． 58 4.3.4在空氣中燒結500℃奈米碳管之循環伏安行 為．．．．．．．．．．．
．．．．．．．． 60 4.3.5電泳沉積30分鐘後奈米碳管之循環伏安行 為．．．．．．．．．．．．．．．．．． 62 第五章 結論 5.1結論．．．．．．．．．．．．．．．．．．．． 65 5.2未來研究方向．．．．．．．．．．．．．．．． 65 參 考文獻．．．．．．．．．．．．．．．．．．．．．．． 67
REFERENCES
[1] 馬振基，“奈米材料科技原理與運用”，全華科技圖書股份有限公司，92年。
[2] H. W. Kroto, J. R. Heath, S. C. O’Brien, R. F. Curl and R. E. Smalley, “buckminsterfullerene.” Nature, 318 (1985) 162-163.
[3] S. Iijima, “Helical microtubules of graphitic carbon,” Nature, 354 (1991) 56 [4] D. S. Bethune, C. H. Kiang, M. S. de Vries, G. Gorman, R.
Saroy, J. Vazquez, and R. Beyers. “Cobalt-catalysed growth of carbon nanotubes with single-atomic-layer walls,” Nature, 363 (1993) 605.
[5] E. Thostenson, Z. Ren, T. W. Chou, “Advances in the Science and Technology of Carbon Nanotubes and their Composites: A review,”
Composites Science and technology, 61 (2001) 1899-1912 [6] Kotz.R, Carlen M “Principle and applications of electrochemical capacitors.”
Eletrchimica Acta, 45 (2000)2483-2498 [7]Burke A. “Ultracapacitors: why, how, and where is the technology.” Journal of Power Sources, 91 (2000) 37-50 [8]C. Niv, E. K. Sichel, R. Hoch, D. Moy, H. Tennent, “High power electrochemical capacitors based on carbon nanotube electrodes,” Appl. Phys. Lett., 70 (1997) 1480-1482 [9]M. S. Dresselhaus, G. Eklund, P.C. Eklund, “Fullerenes and carbon nanotubes,”
Academic Press,San Diego, (1996) 224 [10]M. M. J. treacy, T. W. Ebbesen , J. M. Gibson, “Exceptionally high Young's modulus observed for individual carbon nanotubes,” Nature 381 (1996) 678-680 [11]MR Falvo, GJ Clary, RM II Taylor, V Chi, FP Brooks, “S
Washburn,RSuperfine, ” Nature, 389 (1997) 582 [12]N. Krishnankutty, C. Park, N. M. Rodriguez, R. T. K. Baker, “Mechanical and thermal properties of carbon nanotubes,” Carbon, 27 (1995) 925-930 [13]J. Kong, N. R. Franklin, C. Zhou, M. G. Chapline, S. Peng, K. Cho,
“Nanotube molecular wires as chemical sensors,” H. Dai, Science, 287 (2000) 622 [14]J. H. Hafner, C. L. Cheung, C. M. Lieber, “Direct Growth of Single-Walled Carbon Nanotube Scanning Probe Microscopy Tips,” Journal America Chemical Society, 121 (1999) 9750 [15]B.
Vigolo, A. Penicaud, C. Coulon, C. Sauder, R. Pailler, C. “Macroscopic Fibers and Ribbons of Oriented Carbon Nanotubes,” Journet,P.
Bernier, and P. Poulin, Science, 290 (2000) 1331 [16]I. Corni, M. P. Pyan, A. P. Boccaccini, “Electrophoretic deposition : forom traditional ceramics to nanotechnology,” journal of the European cerarnic society, 28 (2008) 1353-1367.
[17]A. T. Kuhn,“Industrial Plectrochemical Processes,”Elsevier, Amsterdam, The Netherlands, (1971) 128 [18]A. Formetro, L. Montanaro, M.
V. Swain, “Micromechanical characterization of electrophoretic-deposited green films,” J. Am. Ceram. Soc., 82 (1999) 3521–3549 [19]J. A.
Lewis, “Colloidal processing of ceramics,” J. Am. Ceram. Soc. 82 (2000) 2341-59 [20] R. Z. Ma, J. Liang, B. Q. Wei, B. Zhang, C. L. Xu, D. H.
Wu, J. “Study of electrochemical capacitors utilizing carbon nanotube electrodes,” Power Sources 84 (1999) 126–129.
[21]J. A. Siracuse, J. B. Talbot, E. Sluzky, and K. R. Hesse, “The adhesive agent in cataphoretically coated phosphor screens,” J. Electrochem.
Soc. 137 (1990) 346-348.
[22] B. E. Russ, and J. B. Talbot, “An analysis of the binder formation in electrophoretic deposition,” J. Electrochem. Soc. 145 (1998) 1253-1256.
[23]B. Gao, G. Z. Yue, Q. Qiu, Y. Cheng, H. Shimoda, L. Fleming, and O. Zhou, “Fabrication and Electron Field Emission Properties of Carbon Nanotube Films by Electrophoretic Deposition,” 23 (2001) 1770-1773 [24]A. J. Bard and L. R. Faulkner, “Electrochemical Methods, Fundamentals and Applications”,John Wiley & Sons, Singapore (1980).
[25]D. Pletcher, “A First Course in Electrode Processes”, The Electrochemical Consultancy, England (1991).
[26]D. R. Crow, “Principles and Applications of Electrochemistry”, 2nd Ed. Chapman and Hall Ltd. London (1979) [27]胡啟章, “電化學原 理與方法”,五南圖書出版公司, 2002年 [28]陳奕勳, “陽極沈積錳系水合氧化物於電化學超級電容器之應用”,國立中正大學化學工程研 究所碩士論文, 2003.
[29]薛皓之, “以無電鍍鎳觸媒成長奈米碳管應用於電化學超級電容器之研究”,大葉大學電信工程學系碩士論文,2006.
[30]A. J. Bard, and L. R. Faulkner, “Electrochemical Principles, Methods, and Applications,” Oxford University, Britain, (1996).
[31]Bard, A. J.; Faulkner, L. R., “Electrochemical Methods Fundamental and Application,” John Wiley & Sons, Canada, 1980.
[32]J. S. Mattson, and Jr. H. B. Mark, “Activated Carbon: Surface Chemistry andAdsorption from Solution,” Wiley-Vch: New York, (1998) [33]J. P. Zheng and T. R. jow, “A New Charge Strage Mechanism for Electrochemical Capacitors,” J. Electrochem. Soc., 142, (1995) L6-L8 [34]H. Zhao, H. Song, Z. Li, G. Yuan, Y. Jin, “Electrophoretic deposition and field emission properties of patterned carbon nanotubes,”
Appl.Surf. Sci. (2005)242 [35] C. Du and N. Pan, “High power density supercapacitor electrodes of carbon nanotube films by electrophoretic deposition,” Nanotechnology 17 (2006) 5314–5318 [36] T. Ito, L. Sun, R. M. Crooks, “Electrochemical Etching of Individual Multiwall Carbon Nanotubes,” Electrochem. Solid State Lett. 2003, 6, C4-C7.
[37] Y. S. Park, Y. C. Choi, K. S. Kim, D. C. Chung, “High yield purification of multiwalled carbon nanotubes by selective oxidation during
thermal annealing,” Carbon 39 (5) (2001) 655– 661.
[38] A. R. Boccaccini, J. Cho, J. A. Roether, Boris J.C. Thomas, E. J. Minay, Milo S.P. Shaffer, “Electrophoretic deposition of carbon nanotubes,
” Carbon 44 (2006) 3149–3160 [39]C. Lia, D. Wang, T. Liang, X. Wang, J. Wua, X. Hu, J. Liang, “Oxidation of multiwalled carbon nanotubes by air: benefits for electric double layer capacitors,” Powder Technology 142 (2004) 175– 179 [40] C. Du and N. Pan,
“Supercapacitors using carbon nanotubes films by electrophoretic deposition,” Journal of Power Sources 160 (2006) 1487–1494 [41] S. R. C.
Vivekchand, A. Govindaraj, Md. Motin Seikh and C. N. R. Rao, "A new method of purification of carbon nanotubes based on hydrogen treatment", J. Phys. Chem. B 108 (2004) 6935-6937.
[42] A. Dekanski , J. Stevanovic , R. Stevanovic , B. Z. Nikolic , V. M. Jovanovic, “Glassy carbon electrodes I. Characterization and electrochemical activation,” Carbon 39 (2001) 1195–1205
