通过紫外-可见、扫描电镜、方波伏安、循环伏安、稳定性考察, 研究了十六烷基三甲基溴化铵(CTAB)作为钒电池电解液的添加剂对电解液的稳定性和电化学活性的影响, 并对其机理进行了探讨. 研究结果表明: 电解液中CTAB胶束的季铵头部基团与五价钒作用, 阻止五价钒的进一步聚合, 从而抑制了五价钒的结晶. 同时, 添加剂在电极和电解液界面上, 形成稳定的半球状颗粒, 起到胶束催化V(IV)/V(V)氧化还原电对的作用. 交流阻抗、充放电测试表明添加CTAB的电解液大大减小电荷传递电阻, 使双电层电容增大一倍, 提高电解液的电化学反应活性, 这与CTAB的胶束催化相吻合.
Hexadecyl trimethyl ammonium bromide (CTAB) was used as the additive in electrolyte for vanadium redox flow battery. Its stability and electrochemical performance were investigated by UV-Vis absorption spectrophotometry, scanning electron microscope(SEM), square wave voltammetry(SWV), cyclic voltammetry(CV) and examination of stabilization. The results show that the quaternary ammonium headgroups of CTAB micelles interacting with V(V) ions in electrolyte prevents pentavalent vanadium from further polymerization, which leads to a good suppression of the crystallization. The stable hemispherical particles forming at the graphite-liquid interface catalyze the redox reaction of V(IV)/V(V), which is called Micellar catalysis. EIS and charge-discharge tests show that the adding of CTAB makes charge transfer resistance much smaller, and doubles double-layer capacitance, so that the electrochemical reaction activity of the electrolyte improved, which is consistent with CTAB micellar catalysis.
[1]Fabjan C, Garche J, Harrer B, et al. The vanadium redox-battery: an efficient storage unit for photovoltaic systems. Electrochem. Acta, 2001, 47(5): 825-831.
[2]Joerissen L, Garche J, Fabjan Ch, et al. Possible use of vanadium redox-flow batteries for energy storage in small grids and stand- alone photovoltaic systems. J. Power Sources, 2004, 127(1/2): 98-104.
[3]Zhong S, Skyllas-Kazacos M. Electrochemical behaviour of vanadium(V)/vanadium(IV) redox couple at graphite electrodes. J. Power Sources, 1992, 39(1): 1-9.
[4]Skyllas-Kazacos M, Cheng M, Skyllas-Kazacos M. Vanadium redox cell electrolyte optimization studies. J. Appl. Electrochem. , 1990, 20(3): 463-467.
[5]Skyllas-Kazacos M, Menictas C, Skyllas M. Thermal stability of concentrated V(V) electrolytes in the vanadium redox cell. J. Electrochem. Soc. , 1996, 143(4): 86-88.
[6]Skyllas-Kazacos M, Rychick M, Robins R. All-vanadium Redox Battery. US Patent, 4786567, 1988.11.22.
[7]Skyllas-Kazacos M, Grossmith F. Efficient vanadium redox flow cell. Journal of the Electochemical Society, 1987, 134(12): 2950-2953.
[8]Adamson A W. Physical Chemistry of Surfaces, 5th ed. New York: Wiley, 1990.
[9]Hiemenz P C. Principles of surface and colloid chemistry. New York: Marcel Dekker, 1986.
[10]Heyrovsky J, Kuta J. Principles of polarography. New York: Academic Press, 1966.
[11]Franklin T C, Mathew S. Surfactants in solution., Mittall K L, editor. New York: Plenum, 1989: 267-286.
[12]Vittal R, Gomathi H, Kim K J. Beneficial role of surfactants in electrochemistry and in the modification of electrodes. Advances in Colloid and Interface Science, 2006, 119(1): 55-68.
[13]戚文彬, 朱利中. 混合表面活性剂在光度分析中的应用和发展. 分析测试通报, 1986(5): 1-7.
[14]Ishibashi N, Kina K. Sensitivity enhancement of the fluorometric determination of aluminum by the use of surfactant. Anal. Lett. , 1972, 5(9): 637-641.
[15]Chernova R K. Effect of some colloidal surfactants on spectrophotometric characteristics of metal chelates with chromophoric organic reagents. Zh. Anal. Khim. , 1977, 32(8): 1477-1486.
[16]Qi W B, Zhu L Z. Study of the mechanism of synergic sensitizing effect on color reaction by mixed ionic-nonionic surfactants. Chem. J. Chin. Univ. , 1986, 7: 407.
[17]Tharwat M, Awad A, Rashwan F. Effect of surfactants on kinetics of reduction of vanadium(V) in universal buffer solutions at the dropping mercury electrode. Revue Roumaine de Chimie, 1981, 26(3): 491-501.
[18]Avilova G I, Afanas'ev B N. Kinetics of the vanadium (III) -vanadium (II) reaction in the presence of surfactants. Elektrokhimiya, 1976, 12: 11.
[19]赵振国. 束催化与微乳催化. 北京: 化学工业出版社, 2006: 24.
[20]Burgess I, Jeffrey C A, Cai X, et al. Direct visualization of the potential-controlled transformation of hemimicellar aggregates of dodecyl sulfate into a condensed monolayer at the Au(111) electrode surface. Langmuir, 1999, 15(8): 2607-2616.
[21]Jiang M J, Dang Z M, Yao S H, et al. Effect of surface modification of carbon nanotubes on microstructure and electrical property in the nanotubes/rubber-matrix nanocomposites. Chemical Physics Letters, 2008, 457(4/5/6): 352-356.
[22]Choi K S, McFarland E W, Stucky G D. Electrocatalytic properties of thin mesoporous platinum films synthesized utilizing potential- controlled surfactant assembly. Advanced Materials, 2003, 15(2323): 2018-2021.
[23]Nielsch K, Wehrspohn R B, Barthel J, et al. Hexagonally ordered 100 nm period nickel nanowire arrays. Appl. Phys. Lett. , 2001, 79(9): 1360-1362.
[24]徐洪峰, 卢 璐, 朱少敏(XU Hong-Feng, et al). 石墨纳米纤维用作质子交换膜燃料电池催化剂载体. 催化学报(Chinese J. Catal.), 2008, 29(6): 542-546.
[25]Zhong Q L, Qing D H, Rusling J F. Films of hemoglobin and didodecyldimethylammonium bromide with enhanced electron transfer rates. Journal of Electroanalytical Chemistry, 1967, 423: 59-66.
[26]Fendler J H, Fendler E. Catalysis in micellar and macromolecular systems. New York: Academic Press, 1975.
[27]Marcus R A. Electron transfer reactions in chemistry: theory and experiment. Rev. Mod. Phys., 1997, 65(3): 599-610.
[28]Tavernier H L, Laine F, Fayer M D. Photoinduced intermolecular electron transfer in micelles: dielectric and structural properties of micelle headgroup regions. J. Phys. Chem. A, 2001, 105(39): 8944-8957.
[29]曹楚南, 张鉴清. 电化学阻抗谱导论. 北京: 科学出版社, 2002: 84-95.
[30]贾 铮, 戴长松, 陈 玲. 电化学测量方法.北京: 化学工业出版社, 2006: 61.
