含二茂铁离子液体电容器的电化学性能

对以含二茂铁(ferrocene, Fc)离子液体1-乙基-3-甲基咪唑四氟硼酸盐(1-ethyl-3-methylimidazolium tetra-fluoroborate, BMIm]BF4)作为电解液, 高比表面积的多孔炭作为电极材料构成的电容器的电化学行为进行了探讨. 循环伏安和恒流充放电测试结果表明,含二茂铁离子液体在多孔炭中发生氧化还原反应, 并且该氧化还原反应是扩散控制, 高度可逆的过程. 0.01 mol·L-1 BMIm]BF4/Fc在电流密度为1 mA·cm-2时的平均比电容为163 F·g-1, 比纯BMIm]BF4的比电容高63%. 平均比电容的增加表明由Fc参与的氧化还原反应生成的法拉第电容对电容器的总电容有很大的贡献. 同时, 以0.01 mol·L-1 BMIm]BF4/Fc作电解液的电容器的功率密度为400 W·kg-1, 能量密度高达37.5 Wh·kg-1, 达到了电池的水平.

Eelectrochemical Performance of Capacitors Using [BMIm]BF4/Fc as Electrolyte

The electrochemical behaviors of ferrocene (Fc)-containing ionic liquid BMIm]BF4 were investigated in a system, which used ferrocene-containing ionic liquid as electrolyte, porous carbon as electrode materials. The cyclic voltammetry and constant current charge-discharge results indicated that redox reaction of Fc happened in the porous carbon, and which was a diffusion-controlled, highly reversible redox reaction. The average specific capacitance of 0.01 mol·L-1 BMIm]BF4/Fc at a current density of 1 mA·cm-2 was 163 F·g-1, 63% higher than that of pure BMIm]BF4. The increase of average specific capacitance indicates that the faradic pseudocapacitance associated with Fc species in the redox reactions has a considerable contribution to the total capacitance of ECs (electrochemical capacitors). At the same time, it shows a power density of 400 W·kg-1 as well as energy density of 37.5 Wh·kg-1 approaching the level of a practical battery.