Realistic Ion Dynamics through Charge Renormalization in Nonaqueous Electrolytes,The Journal of Physical Chemistry B

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Realistic Ion Dynamics through Charge Renormalization in Nonaqueous Electrolytes
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2020-04-02 , DOI: 10.1021/acs.jpcb.0c01197
Zhixia Li _{1,

2,

3} , Lily A. Robertson _{1,

4,

5} , Ilya A. Shkrob _{1,

5} , Kyle C. Smith _{3,

6,

7,

8} , Lei Cheng _{1,

9} , Lu Zhang _{1,

5} , Jeffrey S. Moore _{1,

3,

4,

7} , Y Z _{1,

2,

3,

8,

10}

Affiliation

Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois61801, United States
Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana−Champaign, Urbana, Illinois61801, United States
Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois61801, United States
Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois60439, United States
Department of Mechanical Science and Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois61801, United States
Department of Materials Science and Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois61801, United States
Program of Computational Science and Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois61801, United States
Materials Science Division, Argonne National Laboratory, Lemont, Illinois60439, United States
Department of Electrical and Computer Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois61801, United States

While many practically important electrolytes contain lithium ions, interactions of these ions are particularly difficult to probe experimentally because of their small X-ray and neutron scattering cross sections and large neutron absorption cross sections. Molecular dynamics (MD) is a powerful tool for understanding the properties of nonaqueous electrolyte solutions from the atomic level, but the accuracy of this computational method crucially depends on the physics built into the classical force field. Here, we demonstrate that several force fields for lithium bistriflimide (LiTFSI) in acetonitrile yield a solution structure that is consistent with the neutron scattering experiments, yet these models produce dramatically different ion dynamics in solution. Such glaring discrepancies indicate that inadequate representation of long-range interactions leads to excessive ionic association and ion-pair clustering. We show that reasonable agreement with the experimental observations can be achieved by renormalization of the ion charges using a “titration” method suggested herewith. This simple modification produces realistic concentration dependencies for ionic diffusion and conductivity in <2 M solutions, without loss in quality for simulation of the structure.

中文翻译：

通过非水电解质中电荷重整化的逼真的离子动力学

尽管许多实际上重要的电解质都包含锂离子，但由于它们的X射线和中子散射截面小而中子吸收截面大，因此这些离子的相互作用特别难以通过实验探测。分子动力学（MD）是从原子水平理解非水电解质溶液特性的有力工具，但是这种计算方法的准确性关键取决于经典力场中内置的物理学。在这里，我们证明了在乙腈中的Bistriflimide锂（LiTFSI）的多个力场产生的溶液结构与中子散射实验一致，但是这些模型在溶液中产生了截然不同的离子动力学。这种明显的差异表明，远距离相互作用的不充分表达会导致过度的离子缔合和离子对簇聚。我们表明，通过使用本文建议的“滴定”方法对离子电荷进行重新归一化，可以与实验观察结果达成合理的一致性。这种简单的修改在<2 M的溶液中产生了离子扩散和电导率的实际浓度依赖性，而不会因模拟结构而降低质量。

更新日期：2020-04-03

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