钒
电场
膜
渡线
化学物理
电极
离子
流动电池
化学
材料科学
电解质
分析化学(期刊)
无机化学
色谱法
物理
量子力学
物理化学
人工智能
生物化学
有机化学
计算机科学
作者
Xiaoling Yang,Qiang Ye,Ping Cheng,Tianshou Zhao
出处
期刊:Applied Energy
[Elsevier]
日期:2015-05-01
卷期号:145: 306-319
被引量:112
标识
DOI:10.1016/j.apenergy.2015.02.038
摘要
A thorough understanding of the mechanisms of ion crossover through the membranes in vanadium redox flow batteries (VRFBs) is critically important in making improvements to the battery’s efficiency and cycling performance. In this work, we develop a 2-D VRFB model to investigate the mechanisms of ion crossover and the associated impacts it has on the battery’s performance. Unlike previously described models in the literature that simulated a single cell by dividing it into the positive electrode, membrane, and negative electrode regions, the present model incorporates all possible ion crossover mechanisms in the entire cell without a need to specify any interfacial boundary conditions at the membrane/electrode interfaces, and hence accurately captures the Donnan-potential jumps and steep gradient of species concentrations at the membrane/electrode interfaces. With our model, a particular emphasis is given to investigation of the effect of the electric field on vanadium ion crossover. One of the significant findings is that an electric field exists in the membrane even under the open-circuit condition, primarily due to the presence of the H+ concentration gradient across the membrane. This finding suggests that vanadium ions can permeate through the membrane from H+-diluted to H+-concentrated sides via migration and convection. More importantly, it is found that the rate of vanadium ion crossover and capacity decay during charge and discharge vary with the magnitude of the electric field, which is influenced by the membrane properties and operating conditions. The simulations suggest that enhancing the electric-field-driven flow is a potential approach to minimizing the battery’s capacity decay.
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