A novel ionic liquid (IL) 1-ethyl-2,3-dimethylimidazolium tetrafluoroborate ([Emmim][BF₄]) with trialkyl substitution imidazolium cation was synthesized, and its binary system blended with acetonitrile (ACN) under different concentrations were prepared and investigated as possible electrolytes for supercapacitors. The physico-chemical properties such as density, viscosity, and electrical conductivity of the binary mixture system were measured from 288.15 to 333.15 K. The temperature dependences of density, viscosity, and electrical conductivity were illustrated and discussed by the Vogel-Fulcher-Tamman (VFT) equation and Arrhenius equation. It was found that the VFT equation was more suitable to [Emmim][BF₄] + ACN system. Further, the important characteristics of this IL-based electrolyte for supercapacitors including the maximum operative voltage, the capacitance, the energy density, and power density were measured and calculated by cyclic voltammetry (CV), electrochemical impedance spectrum (EIS), and galvanostatic charge-discharge. The results show that the performance of the electrolyte can be improved with appropriate ratio of IL. When the concentration of the IL increased to 0.8 mol L⁻¹, the maximum operative voltage increased to 5.9 V, and the specific capacitance achieves 142.6 F g⁻¹. It shows the IL-based mixtures with excellent characteristics are applicable as high-voltage electrolytes for supercapacitors.

中文翻译：

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1-乙基-2,3-二甲基咪唑鎓四氟硼酸盐离子液体混合物作为高压超级电容器的电解质

合成了具有三烷基取代的咪唑鎓阳离子的新型离子液体（IL）1-乙基-2,3-二甲基咪唑鎓四氟硼酸酯（[Emmim] [BF ₄ ]），并制备了其在不同浓度下与乙腈（ACN）混合的二元体系，并研究了超级电容器的电解质。在288.15至333.15 K之间测量了二元混合物系统的物理化学性质，例如密度，粘度和电导率.Vogel-Fulcher-Tamman（ VFT）方程和Arrhenius方程。发现VFT方程更适合[Emmim] [BF ₄] + ACN系统。此外，通过循环伏安法（CV），电化学阻抗谱（EIS）和恒流电荷测量并计算了这种基于IL的超级电容器电解质的重要特性，包括最大工作电压，电容，能量密度和功率密度。 -卸货。结果表明，通过适当的IL比可以改善电解质的性能。当IL的浓度增加到0.8mol L ^-1时，最大工作电压增加到5.9 V，并且比电容达到142.6 F g ^-1。它显示出具有优异特性的基于IL的混合物可用作超级电容器的高压电解质。