| 摘要: | 在現今超級電容工業化中還有許多問題需要解決，而其中又以可靠性以及自放電問題尤為重要，而根據過去文獻，作為電極碳材的孔洞結構、電性以及電化學性質已經被確認為是影響這兩種性質的主要原因，因此為了解決這些問題，活性碳電極的製備將會變得格外重要。
在本文的第一部分將會講述對於氮基團在三聚氰胺、氨氣以及一氧化氮等前驅物碳材表面所進行的分子操縱。根據 XPS 元素測定表明一氧化氮氣體在碳材中更容易形成能夠增加電子以及離子導通率的 N-Q (四級氮官能基)結構。由於其更高濃度的 N-Q 以及 N-O 官能基使其沒有太多表面積減少，AC-NO 電極在 2.5 V-3.0 V 的電位範圍中表現出優異的電化學性能和循環穩定性。從恆電流充放曲線中證實AC電極的電荷儲存油電雙層結構所控制，另外還發現AC電極的電荷逸散(即自放電)以及氣體產生反應取決於氮基團的類型，N-Q 結構較 N-5、N-6 結構更有利於抑制不必要的法拉第副反應。另一方面，具有更多 N-Q 結構的 AC-NO 可以增加電極厚度並增加操作電壓至 3.0 V，且不會大幅降低電化學性能和電極結構的完整性。除了活性材料改質外，本懷描述了黏著劑改質對於孔洞結構、可靠性以及自放電行為的影響。與 PVD F即 PTFE 黏著劑相比，CMC+SBR 黏著劑保留了材料的比表面積並產生更多的中孔結構，並從而獲得更多的電荷儲存量、較高的留存率以及更好的3000次充放循環穩定性。使用了 CMC+SBR 的 AC 電極表現出最低的介面電阻 (Rinter)、更高的電子導通率(σ)和擴散係數 (Da)，而對於可靠性分析的近一步研究表明，使用了 CMC+SBR 黏著劑的 AC電極在 2.4-3.5 V 的電壓範圍中有較低的漏電流，這表示在有機像電解質中的副反應較其他黏著劑來的少。
在使用了CMC+SBR 黏著劑之後 AC 電極之自放電行為(包含電荷重組以及不必要之法拉第副反應)在 50 小時的靜置中皆有著最低的總電壓衰退，這可以歸因於其最高的電子導通率、高界孔率以及高穩定性。此外，加入了CMC+SBR 黏著劑後能夠允許碳電極在惡劣的環境、高電壓或高溫下進行使用。在對於循環後之電極分析後證實使用CMC+SBR 黏著劑之 AC 電極有最低的介面電阻、更高的擴散係數，且沒有雜質繞射峰，這表明 CMC+SBR 黏著劑能夠有利於更好的電荷分布並防止不必要之法拉第副反應在嚴酷條件下進行操作時發生。
;Activated carbon is an essential component for the supercapacitor′s electrodes preparation, whose properties and interactions greatly affect the performances of supercapacitors. Pore structure, electronic properties, and chemical and electrochemical properties of carbon material have been identified as the main factor on reliability problem and self-discharge of supercapacitors, which need to be solved by industrially practical methods.
The first part of this dissertation reported the molecular level manipulation of nitrogen groups configuration on carbon surface that was conducted via post-heat treatment some precursors; melamine, ammonia, and nitrogen monoxide gas. XPS spectral confirmed that NO gas prefers to form higher N-Q formation through nitrogen substitution reaction in carbon bulk, which increased electronic and ionic conductivity. Compared with other electrodes, AC-NO electrode exhibited excellent electrochemical performance and cycle life stability at potential ranges of 2.5 V−3.0 V, due to higher concentration N-Q+N-O groups without much losses of surface area and pore volume. The galvanostatic charge-discharge curve confirmed that the charge storage of AC electrodes is controlled by electrical double layer formation. It also found that the charge leakage and gas evolution of the AC electrode depended on the type of N group, which N-Q being more favorable than N-5 and N-6 to suppress unwanted faradic side reactions. Another advantage, AC-NO with higher N-Q concentration allowed to increased electrode thickness and enlarging cell voltage up to 3.0 V without much reducing the electrochemical performances and electrode structure integrity.
From active material modification to electrode fabrication, this dissertation also describes the effects of various pore structures of binder-modified carbon electrodes on self-discharge behavior and reliability of supercapacitors. The use of CMC+SBR binder preserved specific surface area, pore volume and create more mesopore than PVDF and PTFE binder, leading to higher charge-storage capacity, high retention rate, and better cycle life stability for 3000 cycles. AC+CMC+SBR electrode also showed lower interfacial resistance (Rinter), higher electronic conductivity (σ), and apparent diffusion coefficient (Da) than other AC electrodes. Further investigation on reliability study showed that AC+CMC+SBR electrode had lower leakage current at voltage ranges of 2.4−3.5 V which indicated less parasitic faradic side reactions in organic electrolyte. Dual-phases of SDs were AC+CMC+SBR electrode, charge redistribution, and unwanted faradic side reaction, with the lowest total voltage decay for 50 h which could be attributed to the higher electronic conductivity, high mesopore ratio, and high stability of CMC+SBR. Moreover, employing CMC+SBR binder allowed applying the carbon electrode in severe environments, high voltage, and/or high temperature. SDs post-mortem analysis confirmed that AC+CMC+SBR electrode had the lowest interfacial resistance, better diffusion coefficient, and no impurity diffraction peaks which indicated CMC+SBR binder facilitates preferable charge distribution and prevent undesired parasitic faradic side reactions during severe operation. |
