本研究探討氮摻雜還原石墨烯氧化物(N-doped rGO)在非對稱性的離子液體[EMI][TFSI]中的電容相關特性。我們採用Staudenmaier法將石墨烯氧化物剝離且還原，發現氮摻雜還原石墨烯氧化物的比表面積高於1100oC下未摻雜還原石墨烯氧化物。因此本論文主要探討由氮摻雜還原石墨烯氧化物組成的電容器其如何在電解質[EMI][TFSI]中使用最大的電位窗口範圍。
由白金線作為工作電極測量出離子液體[EMI][TFSI]分解電位窗口範圍為：-1.65 +2.6 V (vs. RHE)。另由循環伏安法量測出氮摻雜還原石墨烯氧化物的離子嵌入嵌出下界電位為-1.6 V，上界電位為1.2 V。當我們在電位窗口為2.0 V的電容器做充放電時，其正、負極的電位變化皆在嵌入嵌出電位範圍內，因此其正、負極的比電容值比會符合從電雙層電容範圍中掃循環伏安圖譜所得到的比電容值比。當在沒有適當的重量比例下將工作電壓設成3.8 V時，我們往往會發現負極的電位易觸及-1.65 V而導致電解質的分解，在個別電位下仔細分析得知電容器電位窗口的主要限制在負極，因此在不對稱的電位窗口中，其正、負極重量比例(M+/M-)應該小於一，我們在正、負極重量比例(M+/M-)為0.736下探討電容器的性能。

This study explores the capacity of nitrogen doped reduced graphene oxide (N-doped rGO) in the asymmetric electrolyte [EMI][TFSI]. We employ the Staudenmaier method to exfoliate and reduce the graphene oxide, and find the sample of N-doped rGO owns a surface area, higher than 1100C undoped rGO. Hence, the capacitor investigation focuses on how to make most of the electrochemical window of [EMI][TFSI] with N-doped rGO.
The electrochemical window of [EMI][TFSI] is measured between -1.65 and +2.6 V (vs. RHE) with platinum electrodes. Another window rarely mentioned in the literature is the intercalation window, which is -1.6 V the lower window limit and +1.2 V (vs. RHE) the upper window limit for N-doped rGO. If we charge/discharge the capacitor in the working window of 2.0 V, the positive and negative potentials vary within the intercalation window. Consequently, the electrode capacitance ratio of positive and negative electrode is near the ratio measured with cyclic voltammetry, assuming energy storage depends on double layer capacitance entirely. When we impose the 3.8 V working window without considering a proper mass balance, we often found the negative electrode exceeds -1.65 V and decomposes the electrolyte. Careful analysis of the electrode potential variations indicates the main restriction is on the negative potential, therefore, the mass ratio of positive over negative (M+/M-) ought to be less than 1 to use the lopsided potential window sufficiently. The capacitor performance of an M+/M- ratio 0.736 is investigated with details.

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