3-D pore-scale resolved model for coupled species/charge/fluid transport in a vanadium redox flow battery
3-D pore-scale resolved model for coupled species/charge/fluid transport in a vanadium redox flow battery
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DOI：
10.1016/j.electacta.2011.12.065
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发表时间：
2012-03
影响因子：
6.6
通讯作者：
G. Qiu;A. Joshi;C. Dennison;K. Knehr;E. C. Kumbur;Ying Sun
中科院分区：
文献类型：
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作者：
G. Qiu;A. Joshi;C. Dennison;K. Knehr;E. C. Kumbur;Ying Sun
钒氧化还原液流电池（VRFB）已成为一种可行的电网规模储能技术，为可再生能源应用提供了具有成本效益的储能解决方案。在本文中，介绍了一种新的方法，用于建模的电解质流，物种和电荷在VRFB中的电极的孔隙尺度的运输机制，即在水平上，直接解决个别碳纤维的几何形状和电解质流。使用X射线计算机断层扫描（XCT）获得电极的详细几何形状，并针对实验确定的孔隙尺度特性（例如，孔隙和纤维直径、孔隙率和表面积）。然后将处理后的XCT数据用作VRFB中电化学过程建模的几何输入。通过孔隙空间的电解质的流动是使用格子玻尔兹曼方法（LBM）建模，而有限体积法（FVM）是用来解决耦合的物种和电荷传输和预测的VRFB在各种条件下的性能。使用Butler-Volmer方程的电化学模型用于提供碳纤维表面处的物种和电荷耦合。结果得到的细胞电位分布，以及局部浓度，超电位和电流密度分布恒电流放电条件下。电池性能作为电解质流速和外部汲取电流的函数进行了研究。本文开发的模型为建立VRFB电极的结构-性质-性能关系提供了有用的工具。
The vanadium redox flow battery (VRFB) has emerged as a viable grid-scale energy storage technology that offers cost-effective energy storage solutions for renewable energy applications. In this paper, a novel methodology is introduced for modeling of the transport mechanisms of electrolyte flow, species and charge in the VRFB at the pore scale of the electrodes; that is, at the level where individual carbon fiber geometry and electrolyte flow are directly resolved. The detailed geometry of the electrode is obtained using X-ray computed tomography (XCT) and calibrated against experimentally determined pore-scale characteristics (e.g., pore and fiber diameter, porosity, and surface area). The processed XCT data is then used as geometry input for modeling of the electrochemical processes in the VRFB. The flow of electrolyte through the pore space is modeled using the lattice Boltzmann method (LBM) while the finite volume method (FVM) is used to solve the coupled species and charge transport and predict the performance of the VRFB under various conditions. An electrochemical model using the Butler–Volmer equations is used to provide species and charge coupling at the surfaces of the carbon fibers. Results are obtained for the cell potential distribution, as well as local concentration, overpotential and current density profiles under galvanostatic discharge conditions. The cell performance is investigated as a function of the electrolyte flow rate and external drawing current. The model developed here provides a useful tool for building the structure–property–performance relationship of VRFB electrodes.