A Zero-Dimensional Model for Electrochemical Behavior and Capacity Retention in Organic Flow Cells
A Zero-Dimensional Model for Electrochemical Behavior and Capacity Retention in Organic Flow Cells
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DOI：
10.1149/1945-7111/ac1c1f
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发表时间：
2021-08
影响因子：
3.9
通讯作者：
S. Modak;David G. Kwabi
中科院分区：
文献类型：
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作者：
S. Modak;David G. Kwabi
全面了解有机液流电池中氧化还原活性化合物的行为对于开发低成本和长使用寿命的液流电池至关重要。我们开发并验证了有机流通池电化学性能的零维模型。该模型模拟法拉第电荷转移、欧姆电阻和质量转移造成的电压损失，以及电池和电解质储存器之间电解质电荷状态的空间变化对电池循环行为的影响。该模型的预测与对称铁氰化物/铁氰化物电池在各种电流密度和电解液流速下的恒定电流和恒定电压循环数据一致。我们通过循环之前获得的电化学阻抗谱和伏安测量来确定模型的电压损失参数，而不是后验拟合。在操作中，电解质充电状态的测量表明，电解质在其储存器和电化学电池之间流动的有限时间可能会显着影响电压-电流行为。通过模拟活性反应物衰减，我们展示了电池中测量的容量衰减如何取决于循环协议和反应物衰减机制。这项工作表明，零维电化学建模有助于阐明容量衰减机制并优化实际有机液流电池所考虑的化学性能。
Comprehensively understanding the behavior of redox-active compounds in organic flow cells is essential to developing low-cost and long service life flow batteries. We develop and validate a zero-dimensional model of the electrochemical performance of an organic flow cell. The model simulates voltage losses from Faradaic charge transfer, Ohmic resistance, and mass transfer, along with the influence of spatial variations in the electrolyte's state-of-charge between the cell and electrolyte reservoir, on the cell's cycling behavior. The model's predictions agree with constant current and constant voltage cycling data for a symmetric ferro-/ferricyanide cell across a wide range of current densities and electrolyte flow rates. We determine the model's voltage loss parameters from electrochemical impedance spectroscopy and voltammetry measurements acquired prior to cycling, rather than fitted a posteriori. In operando measurements of the electrolyte's state-of-charge demonstrate that the finite time for electrolyte flow between its reservoir and the electrochemical cell may significantly affect voltage-current behavior. By modelling active reactant decay, we demonstrate how capacity fade measured in a cell depends on the cycling protocol and reactant decay mechanism. This work shows that zero-dimensional electrochemical modeling helps in elucidating capacity fade mechanisms and optimizing the performance of chemistries under consideration for practical organic flow batteries.