Kopač Lautar Anja, Bitenc Jan, Dominko Robert, Filhol Jean-Sébastien
Department of Materials Chemistry, National Institute of Chemistry, Ljubljana 1000, Slovenia.
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia.
ACS Appl Mater Interfaces. 2021 Feb 24;13(7):8263-8273. doi: 10.1021/acsami.0c19579. Epub 2021 Feb 16.
Insights into the electrochemical processes occurring at the electrode-electrolyte interface are a crucial step in most electrochemistry domains and in particular in the optimization of the battery technology. However, studying potential-dependent processes at the interface is one of the biggest challenges, both for theoreticians and experimentalists. The challenge is pushed further when stable species also depend on the concentration of specific ligands in the electrolyte, such as chlorides. Herein, we present a general theoretical methodology to compute a Pourbaix-like diagram of complex electrolytes as a function of electrode potential and anion's chemical potential, that is, concentration. This approach is developed not only for the bulk properties of the electrolytes but also for electrode-electrolyte interfaces. In the case of chlorinated magnesium complexes in dimethoxyethane, we show that the stability domains of the different species are strongly shifted at the interface compared to the bulk of the electrolyte because of the strong local electric fields and charges occurring in the double layer. Thus, as the interfacial stability domains are strongly modified, this approach is necessary to investigate all interface properties that often govern the reaction kinetics, such as solvent degradation at the electrode. Interface Pourbaix diagram is used to give some insights into the improved stability at the Mg anode induced by the addition of chloride. Because of its far-reaching insights, transferability, and wide applicability, the methodology presented herein should serve as a valuable tool not only for the battery community but also for the wider electrochemical one.
深入了解电极 - 电解质界面发生的电化学过程是大多数电化学领域的关键一步，尤其是在电池技术优化方面。然而，研究界面处电位依赖的过程对理论家和实验家来说都是最大的挑战之一。当稳定物种还取决于电解质中特定配体（如氯化物）的浓度时，这一挑战就更加突出。在此，我们提出一种通用的理论方法，用于计算复杂电解质的类Pourbaix图，该图是电极电位和阴离子化学势（即浓度）的函数。这种方法不仅针对电解质的整体性质，还针对电极 - 电解质界面进行了开发。对于二甲基乙氧基乙烷中的氯化镁配合物，我们表明，由于双层中存在强局部电场和电荷，与电解质本体相比，不同物种在界面处的稳定域发生了强烈偏移。因此，由于界面稳定域被强烈改变，这种方法对于研究所有常常控制反应动力学的界面性质（如电极处的溶剂降解）是必要的。界面Pourbaix图用于深入了解添加氯化物对镁阳极稳定性的改善。鉴于其深远的见解、可转移性和广泛的适用性，本文提出的方法不仅应为电池领域，也应为更广泛的电化学领域提供有价值的工具。
