Electric double layer capacitor and its improved specific capacitance using redox additive electrolyte
Electric double layer capacitor and its improved specific capacitance using redox additive electrolyte
复制标题
DOI：
10.1039/c2ta00210h
复制
发表时间：
2013-01-01
影响因子：
11.9
通讯作者：
Melo, J. S.
中科院分区：
文献类型：
--
作者：
Senthilkumar, S. T.;Selvan, R. Kalai;Melo, J. S.
添加卤素（碘化物，I-）的水性电解质促进生物质衍生的活性炭基双电层电容器的电容行为。为大规模生产超级电容器电极，以凤眼莲为原料，采用ZnCl 2活化法制备活性炭。采用XRD、拉曼光谱、红外光谱、比表面积、孔径和孔容分析等手段对活性炭进行了表征。采用循环伏安法（CV）、恒流充放电（GCD）、电化学阻抗谱（EIS）和循环稳定性等方法研究了SC的电化学性能。3 I（-）/I-3（-）、2 I（-）/I-2、2 I（3）（-）/3 I（2）和I-2/IO 3-对在CV中产生氧化还原峰，在充放电曲线中产生大的法拉第平台。类似地，I-离子改善了电极/电解质界面处的良好离子电导率（较低的电荷转移电阻），这通过EIS研究来确定。在1 M H2SO 4水溶液中计算的比电容和能量密度为472 F g（-1）和9.5 W h kg（-1）。有趣的是，当在1 M H2SO 4电解质中加入0.08 M KI时，实现了比电容和能量密度的近两倍提高，分别为912 F g（-1）和19.04 W h kg（-1），并具有超过4000次循环的优异循环稳定性。随后，将这种改进的比电容和能量密度与作为电解质的添加到1 M H2SO 4中的0.08 M KBr（572 F g（-1），11.6 W h kg（-1））和添加到1 M Na 2SO 4中的0.08 M KI（604 F g（-1），12.3 W h kg（-1））进行比较。
Halogen (iodide, I-) added aqueous electrolyte facilitates the capacitive behaviour of biomass derived activated carbon based electric double layer capacitors. To produce economically viable electrodes in large scale for supercapacitors (SCs), the activated carbons (ACs) prepared from Eichhornia crassipes (common water hyacinth) by ZnCl2 activation. The prepared ACs were characterized by XRD, Raman, FTIR and surface area, pore size and pore volume analysis. The electrochemical properties of the SCs were studied using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycling stability. The 3I(-)/I-3(-), 2I(-)/I-2, 2I(3)(-)/3I(2) and I-2/IO3- pairs produce redox peaks in CV and a large Faradaic plateau in charge-discharge curves. Similarly, I- ions improves the good ionic conductivity (lower charge transfer resistance) at the electrode/electrolyte interface which was identified through EIS studies. The calculated specific capacitance and energy density was 472 F g(-1) and 9.5 W h kg(-1) in aqueous solution of 1 M H2SO4. Interestingly, nearly two-fold improved specific capacitance and energy density of 912 F g(-1) and 19.04 W h kg(-1) were achieved when 0.08 M KI was added in 1 M H2SO4 electrolyte with excellent cycle stability over 4000 cycles. Subsequently, this improved specific capacitance and energy density was compared with 0.08 M KBr added to 1 M H2SO4 (572 F g(-1), 11.6 W h kg(-1)) and 0.08 M KI added to 1 M Na2SO4 (604 F g(-1), 12.3 W h kg(-1)) as electrolytes.