單步驟電膠聯/電聚合沉積法製備高含量氮摻雜碳材與導電高分子自組裝於三維反蛋白石積木結構應用於高效能超級電容

High-level N-doped carbons (of silk fibroin) induced with conducting polymer via co- electrodepositing self-assembly network in 3D inverse opals for high performance supercapacitors

李宗祐(Tsung-Yu Li)

指導教授 ： 陳三元

國立交通大學/工學院/材料科學與工程系所/碩士(2019年)

摘要

因為現今社會能源的需求，有關超級電容的研究發展非常熱門。而高效的超級電容須具備高能量密度、快速充放電以及良好的循環穩定性。然而，為了達到高能量密度，通常在高比表面積碳材中加入偽電容材料如金屬氧化物或導電高分子，但這些偽電容材料不僅降低導電度且在高度充放電下結構易崩解，相較之下，在碳材中摻雜異質原子可提升偽電容且不會降低整體的導電性和充放電穩定性。另外，製備高比表面積多孔材料常需混入高分子基底的連接劑，此不僅降低導電性也使電解質不易擴散充分運用電極之孔洞，並不足以提升能量密度。
本研究以單步驟電膠聯/電聚合方式將蠶絲蛋白(SF)和導電高分子3,4-乙烯基二氧噻吩(EDOT)共電沉積於聚苯乙烯(PS)光子晶體模板，將模板移除並在400度碳化後，得到一氮原子摻雜多孔三維反結構積木碳材電極。其中，蠶絲和聚3,4-乙烯基二氧噻吩因其表面電荷和親疏水特性，在不同濃度和電壓下，會自組裝形成高β片層（β-pleated sheet）含量之特殊結構。此自組裝機制形成之β摺疊可有效幫助來自蠶絲蛋白之氮原子在碳化時留下吡啶氮，不僅提升導電性，更與來自聚3,4-乙烯基二氧噻吩之硫原子以摻雜共同提升此材料之電容。同時，電聚合聚3,4-乙烯基二氧噻吩也用以串聯蠶絲蛋白來維持反結構及其孔洞骨架。而三維反蛋白石積木結構(IO)不僅具有理論最高比表面積，且提供巨孔使電解質可充分擴散於電極表面，連續性骨架更能改善使用連接劑使導電性降低的問題。接著，碳化後形成的微孔分布在骨架上，可進一步增加比表面積提升導電性和電容。因此，我們得到碳化-SF/PEDOT IO (C-SPIO)@0.07% 電極在電流密度0.5 A/g下擁有445 F/g之高比電容值。在以10 A/g循環充放電10000次之後，此電極仍能具有89.8%的電容留存率。此外，在1100 W//kg功率密度下，此電極可達到高能量密度之62 Wh/kg。這些結果顯示出此高含量氮摻雜碳材與導電高分子自組裝於三維反蛋白石之積木結構，具有應用於超級電容電極的極大潛力。

關鍵字

蠶絲蛋白 ； 導電高分子 ； 自組裝 ； 反蛋白石積木結構 ； 超級電容

並列摘要

Due to the high demand of energy, the development of supercapacitors (SCs) is getting more and more popular nowadays. A high-performance SCs should equipped with high energy density, fast powering rate, and great cycling stability. However, compared to hybridize pseduocapacitive materials into carbonaceous materials such as transition metal oxides as well as conducting polymers, doping heteroatoms can increase capacity without losing conductivity and stability. Also, several problems of conventional porous carbon structure exist, such as decreasing of conductivity due to the addition of binder, unconnected pathway for electrolyte to diffuse, and trade-off between energy density and power density. In this work, silk fibroin (SF) doped with conducting polymer monomer (3,4-ethylenedioxythiophene) (PEDOT) were co-electrodepositing into the colloidal photo crystal template of polystyrene (PS) beads via a one-step electrogelation/electropolymerization. After removal of template and carbonization process at 400℃, a newly-design N-doped porous 3D inverse opals (IO) carbon electrode is prepared. Interestingly, because of the surface charge and hydrophobicity of SF and PEDOT, high β-sheet content can be induced by self-assembly of SF and PEDOT under different concentration and applied voltage. This high β-sheet crystalline helped N atom in SF transformed to more pyridine-N under carbonization. Heteroatoms existing in the interlayered N-doped pseudographitic carbon structure from SF pyroportein and filled S-doped EDOT both performed a boosting of capacitance and conductivity. Meanwhile, electropolymerized PEDOT worked as connecter linked SF proteins up to sustain the IO structure, maintaining its hierarchical pore architecture. The IO structure possess theoretically highest surface areas and continuous pore structure to facilitate electrolyte diffusing freely, as well as to take advantage of whole porosity without using a binder. Furthermore, micropores formed by carbonization distribute on the backbone of IO can increase surface area to improve power density and specific capacitance. As a result, the carbonized-SF/PEDOT IO (C-SPIO)@0.07% electrode exhibited a high capacitance of 445 F/g at the current density of 0.5 A/g in 1M LiCl electrolyte. After the galvanostatic charging/discharging rate of 10A/g for 10000 cycles, the electrode still presented good electrochemical stability with capacitance retention ratio of 89.8%. Moreover, the C-SPIO@0.07% could achieve high energy density 62 Wh/kg at power density 1100 W/kg. To sum up, the homemade porous carbon IO electrode holds promise as a supercapacitor for biomedical application or wearable devices as well as a guideline for 3D carbon inverse opals.

並列關鍵字

silk fibroin ； conducting polymer ； self-assembly ； inverse opals ； supercapacitor

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