Data set: Modeling of Electron-Transfer Kinetics in Magnesium Electrolytes: Influence of the Solvent on the Battery Performance

Dataset of the continuum simulations generated and used within the paper "Modeling of Electron-Transfer Kinetics in Magnesium Electrolytes: Influence of the Solvent on the Battery Performance", published in ChemSusChem (2021, 14 (21), 4820-4835, DOI: 10.1002/cssc.202101498). The performance of rechargeable magnesium batteries is strongly dependent on the choice of electrolyte. The desolvation of multivalent cations usually goes along with high energy barriers, which can have a crucial impact on the plating reaction. This can lead to significantly higher overpotentials for magnesium deposition compared to magnesium dissolution. In this work we combine experimental measurements with DFT calculations and continuum modeling to analyze magnesium deposition in various solvents. Jointly, these methods provide a better understanding of the electrode reactions and especially the magnesium deposition mechanism. Thereby, a kinetic model for electrochemical reactions at metal electrodes is developed, which explicitly couples desolvation to electron transfer and, furthermore, qualitatively takes into account effects of the electrochemical double layer. The influence of different solvents on the battery performance is studied forthe state-of-the-art magnesium tetrakis(hexafluoroisopropyloxy)borate electrolyte salt. It becomes apparent that not necessarily a whole solvent molecule must be stripped from the solvated magnesium cation before the first reduction step can take place. For magnesium reduction it seems to be sufficient to have one coordination site available, so that the magnesium cation is able to get closer to the electrode surface. Thereby, the initial desolvation of the magnesium cation determines the deposition reaction for mono-, tri- and tetraglyme, whereas the influence of the desolvation on the plating reaction is minor for diglyme andtetrahydrofuran. Overall, we can give a clear recommendation for diglyme to be applied as solvent in magnesium electrolytes.本数据集为发表于《ChemSusChem》（2021年，第14卷第21期，第4820-4835页，DOI: 10.1002/cssc.202101498）的论文《镁电解质中电子转移动力学建模：溶剂对电池性能的影响》中生成并使用的连续介质模拟数据集。 可充电镁电池的性能极大程度依赖于电解质的选择。多价阳离子的脱溶剂过程通常伴随高能垒，这对电镀反应具有至关重要的影响，进而使得镁沉积的过电位显著高于镁溶解过程。本研究将实验测量与密度泛函理论（DFT）计算及连续介质建模相结合，以分析不同溶剂环境下的镁沉积行为。上述多种方法联用可深化对电极反应、尤其是镁沉积机理的理解。据此，本研究构建了金属电极上电化学反应的动力学模型，该模型明确将脱溶剂过程与电子转移过程耦合，且定性纳入了电化学双电层（electrochemical double layer）的影响效应。本研究针对当前主流的四(六氟异丙氧基)硼酸镁电解质盐，探究了不同溶剂对电池性能的影响。研究发现，在首次还原步骤发生前，并非必须脱去溶剂化镁阳离子结合的全部溶剂分子；对于镁还原过程而言，仅需留出一个配位位点即可使镁阳离子贴近电极表面。针对单甘醇二甲醚、三甘醇二甲醚与四甘醇二甲醚，镁阳离子的初始脱溶剂过程决定了其沉积反应；而对于二甘醇二甲醚与四氢呋喃（tetrahydrofuran），脱溶剂过程对电镀反应的影响则相对微弱。综上，本研究明确推荐将二甘醇二甲醚作为镁电解质的溶剂使用。