Asselin Genevieve, Wei Yang, Gates Leslie, Wang Yang, Bao Junwei Lucas, Xu Wenqian, Sa Niya
Department of Chemistry, University of Massachusetts Boston, Boston, Massachusetts 02125, United States.
Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States.
ACS Appl Mater Interfaces. 2025 Mar 5;17(9):13916-13927. doi: 10.1021/acsami.4c20787. Epub 2025 Feb 21.
A deep molecular-level understanding of the multivalent electrolyte and its correlation with the electrochemical properties is crucial for designing optimized electrolytes for next-generation rechargeable batteries. Comprehensive knowledge of the atomic level of the solvation structure and its connection with electrochemical stability and ion transport properties is especially critical. However, the interaction of these three components coupled with clear atomistic insights is lacking in the literature. Our current contribution evaluates representative electrolytes with the bis(trifluoromethanesulfonyl)imide (TFSI) anions for multivalent cations of Mg, Ca, and Zn, at different ionic conditions with and without a cosolvated environment in ether-based solvent. Two critical problems are investigated: first, resolving the solvation structures in the electrolyte solutions as a function of concentrations through pair distribution function analysis and the corresponding electrochemical transport properties; second, unmasking the quantitative correlation of the atomistic environment with both electrochemical kinetics and cation dependence. We discovered that the magnesium- and calcium-based electrolytes display versatile coordination lengths but poor average anodic stability due to ion pairing with TFSI. On the contrary, the zinc-based electrolytes show the shortest solvent coordination lengths, shielding the Zn cation from rigid solvent interactions and resulting in the highest anodic stabilities. Calcium-based electrolytes exhibit the longest and most concentration-independent coordination lengths. This work provides valuable insights into the molecular structural and electrochemical features of diverse multivalent electrolyte systems with cations in various solvation environments, emphasizing the importance of the solvation structure and construction in designing high-performance electrolytes.
对多价电解质及其与电化学性质的相关性有深入的分子水平理解，对于设计下一代可充电电池的优化电解质至关重要。全面了解溶剂化结构的原子水平及其与电化学稳定性和离子传输性质的联系尤为关键。然而，文献中缺乏这三种成分之间的相互作用以及清晰的原子层面见解。我们目前的研究评估了以双（三氟甲磺酰）亚胺（TFSI）阴离子为代表的电解质，用于镁、钙和锌的多价阳离子，在不同离子条件下，有无共溶剂环境，在醚基溶剂中。研究了两个关键问题：第一，通过对分布函数分析和相应的电化学传输性质，解析电解质溶液中溶剂化结构随浓度的变化；第二，揭示原子环境与电化学动力学和阳离子依赖性之间的定量相关性。我们发现，基于镁和钙的电解质显示出多种配位长度，但由于与TFSI离子配对，平均阳极稳定性较差。相反，基于锌的电解质显示出最短的溶剂配位长度，使锌阳离子免受刚性溶剂相互作用的影响，从而导致最高的阳极稳定性。基于钙的电解质表现出最长且最不依赖浓度的配位长度。这项工作为不同溶剂化环境中含阳离子的多种多价电解质体系的分子结构和电化学特征提供了有价值的见解，强调了溶剂化结构和构建在设计高性能电解质中的重要性。
