美国斯坦福大学崔屹团队揭示了锂离子溶剂化结构与电极电位温度系数的关系。 相关研究成果于2021年1月28日发表在国际顶尖学术期刊《美国化学会杂志》。

电化学电池电压和电极电位的温度系数（TCs）已被广泛用于研究锂离子电池的热安全性和阴/阳极相变。然而，单电极电位TCs的基本意义却鲜为人知。

该项工作中，研究人员发现Li沉积/插层过程中Li离子的去溶剂化过程伴随着相当大的熵变，这对于测量的Li/Li+电极电位的TCs有很大的贡献。为了探索这一现象，研究人员比较了一系列电解液配方中的Li/Li+电极电位TCs，其中Li离子和溶剂分子之间的相互作用强度随溶剂和阴离子种类以及盐浓度的变化而变化。

因此，研究人员建立了电极电位TCs与Li离子溶剂化结构之间的关系，并通过分子动力学模拟进一步验证了它们。结果表明，Li/Li+电极电位TCs的测量提供了有关Li离子溶剂化环境的有价值的知识，并可作为设计未来Li离子/Li金属电池电解液的筛选工具。

附：英文原文

Title: Correlating Li-Ion Solvation Structures and Electrode Potential Temperature Coefficients

Author: Hansen Wang, Sang Cheol Kim, Tomás Rojas, Yangying Zhu, Yanbin Li, Lin Ma, Kang Xu, Anh T. Ngo, Yi Cui

Issue&Volume: January 28, 2021

Abstract: Temperature coefficients (TCs) for either electrochemical cell voltages or potentials of individual electrodes have been widely utilized to study the thermal safety and cathode/anode phase changes of lithium (Li)-ion batteries. However, the fundamental significance of single electrode potential TCs is little known. In this work, we discover that the Li-ion desolvation process during Li deposition/intercalation is accompanied by considerable entropy change, which significantly contributes to the measured Li/Li+ electrode potential TCs. To explore this phenomenon, we compare the Li/Li+ electrode potential TCs in a series of electrolyte formulations, where the interaction between Li-ion and solvent molecules occurs at varying strength as a function of both solvent and anion species as well as salt concentrations. As a result, we establish correlations between electrode potential TCs and Li-ion solvation structures and further verify them by ab initio molecular dynamics simulations. We show that measurements of Li/Li+ electrode potential TCs provide valuable knowledge regarding the Li-ion solvation environments and could serve as a screening tool when designing future electrolytes for Li-ion/Li metal batteries.

DOI: 10.1021/jacs.0c10587

Source: https://pubs.acs.org/doi/10.1021/jacs.0c10587