||Studies of Supercapacitor Electrode Based on Hydrous Ruthenium Oxide/Electrospun Carbon Nanofiber Composites
||Department of Chemical Engineering
hydrous amorphous ruthenium oxide
在溶膠-凝膠法製備過程中，添加界面活性劑能有效提升釕氧化物附著於碳纖維上的含量，另外，透過在空氣氛圍下對釕氧化物及碳纖維複合膜進行熱處理會造成RuO2顆粒的燒結和結晶度提升，能使導電度增加並提升複合材料的電容表現。經300 ℃熱處理後，添加sodium dodecyl sulfate (SDS)所製備的樣品在纖維表面呈現RuO2皺狀結構，並具有較大之孔徑尺寸；添加N-dodecyl-N,N-dimethylammonium-1-propane-3-sulfonate (SB12)及cetyltrimethylammonium bromide (CTAB)之樣品，經由煅燒處理後，釕氧化物顆粒逐漸轉變為柱狀結構，且含結晶型釕氧化物增加，其中添加CTAB之樣品具有最高比例之結晶型RuO2。添加SDS所製備的複合膜，以三維連續的碳纖維作為導電支架，RuO2·xH2O具有皺紋狀結構及最適當的含水不定型與結晶型釕氧化物的比例，為電子和離子提供了快速擴散途徑，其於2 mV / s的掃描速率下具有547 F / g的最高比電容，而2000圈充放電之循環壽命顯示其電容滯留率為100.7 %。
研究第二部分以初濕含浸法經不同含浸次數製備複合纖維。透過此法能使釕氧化物均勻沉積並包覆於碳纖維表面，並能藉由改變含浸次數控制釕氧化物於纖維上之含量。在經過300 ℃熱處理後，隨著碳纖維上釕含量的增加，會使碳氧化的情形更加顯著，因而纖維直徑減小。此外，熱處理亦會些微提升結晶型釕氧化物的比例，使得電荷轉移阻力下降，能貢獻於更高的電容值。然而，當含浸次數為10次時，過高的結晶型態釕氧化物比例使得H+傳遞受阻，造成電容值下降。經由掃描速率2 mV/s下之循環伏安測試，含浸5次之複合纖維具有最高的比電容值544 F/g，此歸因於碳纖維上適當的釕氧化物含量，及熱處理後最有利於電化學反應之不定型與結晶型態釕氧化物比例，其於循環壽命測試經2000圈充放電後電容滯留率仍有97.7 %，顯示材料在經釕改質後仍能維持其穩定性。
The objective of this study is to synthesize composites composed of high capacitive RuO2·xH2O and high electrically-conductive carbon materials, and we aimed at understanding the correlation between the microstructure and electrochemical performance of these composite electrodes. In the sol-gel approach, adding surfactants in precursor solution facilitated the RuO2·xH2O particles attached on carbon nanofibers. When the composites were thermally treated in air atmosphere, RuO2·xH2O particles were slightly sintered and the crystallinity of RuO2 was increased, which resulted in an enhancement of electron transfer and capacitive performance of the composites. After annealing at 300 °C, the composite prepared by adding sodium dodecyl sulfate (SDS) yielded a wrinkle-like structure on the fiber surface. By contrast, the RuO2 particles of composites prepared by adding N-dodecyl-N,N-dimethylammonium-1-propane-3-sulfonate (SB-12) and cetyltrimethylammonium bromide (CTAB) gradually converted to rods after thermal treatment. Among these samples, the RuO2 particles prepared by using SDS delivered the highest specific capacitance of 547 F/g at a scan rate of 2 mV/s and favorable cycling stability with a retention ratio of nearly 100 % after 2000 cycles. This was attributed to the three-dimensional carbon nanofiber network as the conductive backbone, RuO2 with a wrinkle-like hierarchical structure, and an appropriate amount of hydrous amorphous RuO2 that provided the low diffusion resistance for electrons and protons. In the second part, the incipient wetness impregnation approach with various impregnation times was used to prepare composite fibers. It was obtained that hydrous ruthenium oxides were uniformly dispersed on carbon nanofibers. For the composite impregnated for 10 times, the high content of crystalline RuO2 increased the diffusion resistance for protons. By contrast, the composite impregnated for 5 times exhibited the highest specific capacitance of 544 F/g at a scan rate of 2 mV/s, which was attributed to the favorable content of RuO2 and suitable amount of hydrous RuO2. This composite exhibited a capacitance retention ratio of 97.7 % after the cycling test, suggesting the stability of the composite.
Extended abstract III
第一章 緒論 1
1.1 前言 1
1.2 研究動機與目的 2
第二章 文獻回顧 3
2.1 儲電裝置概述 3
2.2 超級電容器概述 5
2.2.1 電容器原理介紹 5
2.2.2 超級電容器介紹 6
2.2.3 電雙層電容器介紹 9
18.104.22.168 電雙層電容原理與結構 9
22.214.171.124 電極孔隙限制 14
2.2.4 擬電容器介紹 18
2.2.5 電極材料 19
2.2.6 超級電容器應用與發展 24
2.3 以電紡絲製備高分子奈米纖維 26
2.3.1 電紡絲技術簡介 26
2.3.2 電紡絲製程影響參數 28
2.3.3 PAN奈米纖維熱處理 32
2.3.4 奈米碳纖維表面進行硝酸改質 34
2.3.5 奈米碳纖維應用為超級電容電極材料 34
2.4 釕氧化物/碳纖維複合膜 35
2.4.1 釕氧化物特性與應用 35
2.4.2 RuO2電極製備方法 39
2.4.3 製備釕氧化物/碳材複合材料 42
第三章 實驗方法與步驟 45
3.1 實驗藥品 45
3.2 實驗儀器 46
3.2.1 儀器參數設定 46
3.2.2 電紡絲裝置 47
3.3 實驗步驟與流程圖 47
3.3.1 製備奈米碳纖維薄膜及其表面改質 49
3.3.2 製備釕氧化物/奈米碳纖維複合薄膜 50
3.3.3 釕氧化物/奈米碳纖維複合薄膜儀器檢測分析 52
3.4 實驗儀器簡介及參數設定 52
3.5 電極片組裝及電化學分析 55
第四章 結果與討論 60
4.1 以sol-gel法製備RuO2·xH2O/CNF複合膜 60
4.1.1 RCNF複合膜熱重分析 60
4.1.2 RCNF複合膜表面形貌分析 62
4.1.3 RCNF複合膜元素組成分析 70
4.1.4 RCNF複合膜微結構分析 74
4.1.5 RCNF複合膜電化學測試 94
4.2 以incipient wetness impregnation法製備RuO2·xH2O/CNF複合膜 116
4.2.1 IMP複合膜熱重分析 116
4.2.2 IMP複合膜表面形貌分析 118
4.2.3 IMP複合膜元素組成分析 124
4.2.4 IMP複合膜微結構分析 127
4.2.5 IMP複合膜電化學測試 149
4.2.6 總結 163
第五章 結論 165
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