论文标题
通过量化中尺度时空异质性，通过颗粒多孔电极中的操作数电化学动力学
Operando Electrochemical Kinetics in Particulate Porous Electrodes by Quantifying the Mesoscale Spatiotemporal Heterogeneities
论文作者
论文摘要
电化学能源系统依靠颗粒多孔电极来存储或转换能量。引入了三维多孔结构，以最大化界面区域以提高系统性能，但时空异质性源于材料热力学将电荷转移过程定位在可用的界面的有限部分上。在这里，我们演示了一种简单但精确的方法，可以直接跟踪和分析在实际的石墨多孔电极中，在中尺度上的操作数（即局部和反应）接口，以获得真正的局部电流密度，事实证明，这比现有研究所采用的全球平均电流密度高两个幅度。我们的结果解决了从电分析测量和第一原理预测中得出的动力学参数之间的长期差异。与普遍的信念相矛盾，一旦在多孔电极中出现时空反应异质性，电化学动力学就不会受到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 porous structures were introduced to maximize the interfacial area for better overall performance of the system, spatiotemporal heterogeneities arose from materials thermodynamics localize the charge transfer processes onto a limited portion of the available interfaces. Here, we demonstrate a simple but precision method that can directly track and analyze the operando (i.e. local and reacting) interfaces at the mesoscale in a practical graphite porous electrode to obtain the true local current density, which turned out to be two orders of magnitude higher than the globally averaged current density adopted by existing studies. Our results resolve the long-standing discrepancies between kinetics parameters derived from electroanalytical measurements and from first principles predictions. Contradictory to prevailing beliefs, the electrochemical dynamics is not controlled by the solid-state diffusion process once the spatiotemporal reaction heterogeneities emerge in porous electrodes.
