物理化学学报 >> 2006, Vol. 22 >> Issue (04): 403-408.doi: 10.1016/S1872-1508(06)60012-0

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全钒液流电池高浓度下V(IV)/V(V)的电极过程研究

文越华;张华民;钱鹏;赵平;周汉涛;衣宝廉   

  1. 中国科学院大连化学物理研究所, 燃料电池工程中心, 辽宁 大连 116023; 北京防化研究院军用电源发展与研究中心, 北京 100083
  • 收稿日期:2005-09-08 修回日期:2005-11-14 发布日期:2006-04-10
  • 通讯作者: 张华民 E-mail:zhanghm@dicp.ac.cn

Investigations on the Electrode Process of Concentrated V(IV)/V(V) Species in a Vanadium Redox Flow Battery

WEN Yue-Hua;ZHANG Hua-Min;QIAN Peng;ZHAO Ping;ZHOU Han-Tao;YI Bao-Lian   

  1. Full Cell R&D Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China; Chemical Defence Institute, Beijing 100083, P. R. China
  • Received:2005-09-08 Revised:2005-11-14 Published:2006-04-10
  • Contact: ZHANG, Hua-Min E-mail:zhanghm@dicp.ac.cn

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摘要： 采用循环伏安、低速线性扫描和阻抗技术, 以石墨为电极, 研究了V(IV)/V(V)在较高浓度下的电极过程. 结果表明, 采用2.0 mol•L-1 的V(IV)溶液时, H2SO4浓度低于2 mol•L-1, V(IV)/V(V)反应极化大, 可逆性差, 表现为电化学和扩散混合控制; H2SO4浓度增至2 mol•L-1以上, V(IV)/V(V)反应的可逆性提高, 转为扩散控制, 且增加H2SO4浓度有利于阻抗的降低; 但H2SO4浓度超过3 mol•L-1, 溶液的粘度和传质阻力大, 阻抗反而增大. 在3 mol•L-1的H2SO4中, 随着V(IV)浓度的增加, 体系的可逆性和动力学改善, 阻抗减小; 但V(IV)浓度超过2.0 mol•L-1, 较高的溶液粘度导致溶液的传质阻力迅速增加, V(IV)/ V(V)的电化学性能衰减, 阻抗增大. 因此, 综合考虑电极反应动力学和电池的能量密度两因素, V(IV)溶液的最佳浓度为1.5～2.0 mol•L-1, H2SO4浓度为3 mol•L-1.

关键词: 全钒液流电池, V(IV)/V(V), 高浓度, 电极过程

Abstract: The electrode process of concentrated V(IV)/V(V) species has been studied at a graphite electrode using cyclic voltammetry, linear polarization, and impedance techniques. The results have revealed that in H2SO4 solution below 2 mol•L-1 containing 2.0 mol•L-1 V(IV), the electrode process of V(IV)/V(V) is controlled by the electrochemical polarization and diffusion with poor reversibility. When the concentration of H2SO4 is above 2 mol•L-1, the electrode process of V(IV)/V(V) turns into the diffusion control with improvement of the reversibility. An increase in concentration of H2SO4 solution facilitates a decrease in impedance, whereas too high concentration of H2SO4 solution(>3 mol•L-1) results in a remarkable increase in the viscosity of solution leading to a large mass transportation polarization, and thus the impedance starts to increase a bit. In 3 mol•L-1 H2SO4 solution, the reversibility and kinetics of V(IV)/V(V) are improved gradually as well as the characteristics of impedance with increasing concentration of V(IV) solution. But, when the concentration of V(IV) solution exceeds 2.0 mol•L-1, the viscosity of the solution is so high that the mass transportation polarization increases considerably, resulting in the deterioration of electrochemical performance of V(IV)/V(V) species and an increase in impedance. Therefore, considering from standpoint of increasing the energy density and electrode kinetics comprehensively, the optimal concentration of H2SO4 is 3 mol•L-1 containing 1.5~2.0 mol•L-1 of V(IV).

Key words: Vanadium redox flow battery, V(IV)/V(V), High concentration, Electrode process