Materials Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States.
Department of Materials Science and Engineering, University of California, Berkeley, 210 Hearst Memorial Mining Building, Berkeley, California 94720, United States.
J Am Chem Soc. 2023 Jun 7;145(22):12181-12192. doi: 10.1021/jacs.3c02222. Epub 2023 May 26.
Out-of-equilibrium electrochemical reaction mechanisms are notoriously difficult to characterize. However, such reactions are critical for a range of technological applications. For instance, in metal-ion batteries, spontaneous electrolyte degradation controls electrode passivation and battery cycle life. Here, to improve our ability to elucidate electrochemical reactivity, we for the first time combine computational chemical reaction network (CRN) analysis based on density functional theory (DFT) and differential electrochemical mass spectroscopy (DEMS) to study gas evolution from a model Mg-ion battery electrolyte─magnesium bistriflimide (Mg(TFSI)) dissolved in diglyme (G2). Automated CRN analysis allows for the facile interpretation of DEMS data, revealing HO, CH, and CHOH as major products of G2 decomposition. These findings are further explained by identifying elementary mechanisms using DFT. While TFSI is reactive at Mg electrodes, we find that it does not meaningfully contribute to gas evolution. The combined theoretical-experimental approach developed here provides a means to effectively predict electrolyte decomposition products and pathways when initially unknown.
非平衡态电化学反应机制一直难以捉摸。然而，这些反应对于一系列技术应用至关重要。例如，在金属离子电池中，电解质的自发降解控制着电极的钝化和电池的循环寿命。在这里，为了提高我们阐明电化学反应性的能力，我们首次将基于密度泛函理论（DFT）的计算化学反应网络（CRN）分析与差分电化学质谱（DEMS）相结合，研究了模型镁离子电池电解质-双三氟甲烷磺酰亚胺镁（Mg（TFSI））在二甘醇（G2）中的气体析出。自动 CRN 分析可以方便地解释 DEMS 数据，揭示出 G2 分解的主要产物为 HO、CH 和 CHOH。通过使用 DFT 来确定基本机制，进一步解释了这些发现。虽然 TFSI 在 Mg 电极上具有反应性，但我们发现它对气体析出没有明显的贡献。这里开发的理论与实验相结合的方法提供了一种有效的方法，可以在最初未知的情况下预测电解质的分解产物和途径。
