Uncovering the mechanisms of electrolyte permeation in porous electrodes for redox flow batteries through real time in situ 3D imaging
Uncovering the mechanisms of electrolyte permeation in porous electrodes for redox flow batteries through real time in situ 3D imaging
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DOI：
10.1039/c8se00174j
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发表时间：
2018-08
影响因子：
5.6
通讯作者：
Farid Tariq;J. Rubio-García;V. Yufit;A. Bertei;B. Chakrabarti;A. Kucernak;N. Brandon
中科院分区：
文献类型：
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作者：
Farid Tariq;J. Rubio-García;V. Yufit;A. Bertei;B. Chakrabarti;A. Kucernak;N. Brandon
不断增长的能源需求加快了对电网规模储能解决方案的需求。在全钒氧化还原液流电池中使用碳基电极已经实现了高功率密度。然而，必须克服根本性的限制，以提高可行性。这项研究解决了钒溶液的渗透到干电极使用时间分辨三维X射线断层扫描，从而有关渗透率和其他润湿现象的微观结构特征和表面性能的碳纤维。结果表明，电解质渗透进行根据一个不均匀的进展前沿，与小的通道状孔填充在第一和剩余的较大的孔填充后，才6小时。钒浓度影响渗透速率，0.5 M VOSO 4的渗透速率较快，而较高和较低浓度的渗透速率较慢。渗透机制与接触角的暂时减小密切相关，揭示了纤维在被电解质溶液处理时变得更加亲水。通过等离子体处理的碳表面基团的改性促进了渗透过程。结果揭示了电解质流动的反直觉行为，其中毛细管驱动的流动被发现是次要的主要润湿机制。揭示这些物理现象对于液流电池的操作程序和避免电池退化至关重要。
Increasing energy demands have expedited the need for grid-scale energy storage solutions. High power densities have been achieved using carbon-based electrodes in all-vanadium redox flow batteries. However, fundamental limitations must be overcome to improve viability. This study addresses the infiltration of vanadium solutions into dry electrodes using time-resolved 3D X-ray tomography, thus relating the rate of permeation and other wetting phenomena to microstructural characteristics and surface properties of carbon fibers. It is shown that electrolyte infiltration proceeds according to a non-uniform progression front, with small channel-like pores filled in first and remaining larger pores filled only after 6 h. The vanadium concentration affects the infiltration rate, being faster for 0.5 M VOSO4 while slower for both higher and lower concentrations. The infiltration mechanism is strongly correlated with the temporal decrease in the contact angle, revealing that fibers become more hydrophilic as they are treated by the electrolyte solution. Modification of carbon surface groups through plasma treatment boosts the infiltration process. The results reveal counter-intuitive behaviors of the electrolyte flow whereby the capillary driven flow is found to be secondary to the primary wetting mechanisms. Uncovering these physical phenomena is essential for operational procedures in flow batteries and avoiding cell degradation.