| Mn2+浓度对钒液流电池正极液的电化学性能影响 |
| Influence of Mn2+ Concentration on the Electrochemical Behavior of the Anolyte for Vanadium Redox Flow Batteries |
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| 摘要: 电解液中金属离子会影响钒液流电池的电化学性能。本文采用循环伏安法和电化学阻抗谱研究了正极液中Mn2+浓度对V(Ⅴ)/V(Ⅳ)电对的氧化还原过程影响规律，发现Mn2+在正极液中没有发生副反应，但严重影响V(Ⅴ)/V(Ⅳ)的反应活性、电极反应可逆性、离子扩散与电荷转移反应等电化学性能。循环伏安测试结果表明Mn2+浓度为0.04~0.13 g·L-1时，V(Ⅴ)/V(Ⅳ)电对电极反应可逆性和反应活性较高，钒离子扩散系数由参照溶液中的8.89×10-7~1.098×10-6增大至1.302×10-6~1.800×10-6 cm2·s-1，提高了~60%；电化学阻抗测试结果表明Mn2+浓度为0~0.04 g·L-1时，V(Ⅴ)/V(Ⅳ)电对电极反应阻抗和界面阻抗均较参照溶液中的增加不明显，但当Mn2+浓度增至0.07 g·L-1时，上述阻抗值较参照溶液增大了25%~28%。基于二者结果，Mn2+对电极反应有不同程度的负面影响，但是适当的Mn2+浓度有利于钒离子的扩散。 |
| 关键词: 钒液流电池 Mn2+ 正极液 循环伏安法 电化学阻抗谱 |
| 基金项目: |
| Abstract: Metal ions in the electrolyte will affect the electrochemical performance of vanadium redox flow batteries (VRBs). The influence of Mn2+ concentration in the anolyte on the redox process of V(Ⅴ)/V(Ⅳ) couple has been investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It is found that Mn2+ doesn′t cause a side reaction, but greatly affects the electrochemical performance of V(Ⅴ)/V(Ⅳ) redox reaction, including reaction activity, reversibility of electrode reaction, vanadium ion diffusion, and charge transfer reaction. The results from CV show that the reversibility and the reaction activity of V(Ⅴ)/V(Ⅳ) couple can be improved as the Mn2+ concentration ranges from 0.04 to 0.13 g·L-1. The vanadium ion diffusion coefficient increases from 8.89×10-7~1.098×10-6 in the reference anolyte to 1.302×10-6~1.800×10-6 cm2·s-1, an increase of ~60%. EIS investigation indicates that the electrode reaction resistance and interfacial resistance of V(Ⅴ)/V(Ⅳ) couple have a slight increase when the Mn2+ concentration is no more than 0.04 g·L-1. When the Mn2+ concentration reaches 0.07 g·L-1, the values of these resistances are 25%~28% higher than those in the reference anolyte. Considering the results from CV and EIS, Mn2+ has different adverse effects on the electrode reaction, but Mn2+ with proper concentration is beneficial to improve the diffusion of vanadium ions. |
| Keywords: vanadium redox flow batteries Mn2+ anolyte cyclic voltammetry electrochemical impedance spectroscopy |
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| 黄 斐,王贵欣,闫康平,罗冬梅.Mn2+浓度对钒液流电池正极液的电化学性能影响[J].无机化学学报,2012,28(5):898-904. |
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