Operando Electrochemical Kinetics in Particulate Porous Electrodes by Quantifying the Mesoscale Spatiotemporal Heterogeneities
Operando Electrochemical Kinetics in Particulate Porous Electrodes by Quantifying the Mesoscale Spatiotemporal Heterogeneities
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DOI：
10.1002/aenm.202003344
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发表时间：
2020-08
影响因子：
27.8
通讯作者：
Shubham Agrawal;P. Bai
中科院分区：
文献类型：
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作者：
Shubham Agrawal;P. Bai
电化学能源系统依靠颗粒多孔电极来存储或转换能量。虽然引入三维(3D)多孔结构是为了最大化界面面积以获得更好的整体性能，但材料热力学引起的时空不均一性正将电荷转移过程局限于可用界面的有限部分。本文介绍了一种简单而精确的方法来直接跟踪和分析实际石墨多孔电极中介观尺度上的操作面(即局部界面和工作界面)，从而得到比已有研究采用的全球平均电流密度高两个数量级的真实局部电流密度。这一结果揭示了电分析测量和第一性原理预测得出的动力学参数之间长期存在的差异。与主流观点相反的是，一旦出现时空反应异质性，电化学动力学就不再受固态扩散过程的控制。
Electrochemical energy systems rely on particulate porous electrodes to store or convert energies. While the three‐dimensional (3D) porous structures are introduced to maximize the interfacial area for better overall performance of the system, spatiotemporal heterogeneities arising from materials thermodynamics are localizing the charge transfer processes onto a limited portion of the available interfaces. Here, a simple but precise method is demonstrated to directly track and analyze the operando (i.e., local and working) interfaces on the mesoscale in a practical graphite porous electrode to obtain the true local current density, which turns out to be two orders of magnitude higher than the globally averaged current density adopted by existing studies. The results shed light on the long‐standing discrepancies in kinetics parameters derived from electroanalytical measurements and from first principle predictions. Contradictory to prevailing beliefs, the electrochemical dynamics are not controlled by the solid‐state diffusion process once the spatiotemporal reaction heterogeneities emerge.