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Understanding the solvation structure of electrolytes is crucial for optimizing the performance and stability of lithium-ion batteries. Novel electrolytes are essential for enhancing electrolyte structure and ensuring better integration with modern electrode systems. Herein, we report a novel weakly solvated ether electrolyte (WSEE) composed of a pure fluorinated ether solvent, which results in an anion-rich solvation structure even at a low salt concentration of 1 M. To explore this, we selected the advanced fluorinated solvent 2,2-difluoroethyl methyl ether (FEME) and compared it with dipropyl ether (DPE), ethylene carbonate (EC), and diethyl carbonate (DEC). The prepared electrolyte systems include DPE with 1 M, 1.8 M, and 4 M LiFSI; FEME with 1 M, 1.8 M, and 4 M LiFSI; and a 1[thin space (1/6-em)]:[thin space (1/6-em)]1 vol% EC/DEC mixture containing 1 M LiPF6. In this work, we comprehensively investigate the Li+ solvation structures using molecular dynamics (MD) simulations and density functional theory (DFT) calculations. Our computational findings indicate the presence of large ion aggregates (AGGs) in each DPE- and FEME-based electrolyte, while SSIPs (68%) are the dominant species in the mixed EC/DEC electrolyte. Notably, the formation of large ion aggregates is more pronounced in FEME-based electrolytes. The dominant solvation structures in the ether-based electrolytes are the anion-rich complexes Li+(FSI−)3(DPE)1 and Li+(FSI−)3(FEME)1. We find that, similar to DPE, the FEME solvent also exhibits weak solvating power across all examined salt concentrations. More specifically, we find that FEME has weaker solvating power than DPE. This behavior is predicted by MD simulations, which indicate a strong preference for Li+ ions to coordinate with FSI− anions within the primary solvation shell. We also observe that the number of unique solvation structures in the ether-based electrolytes increases with salt concentration, with FEME + LiFSI showing slightly more unique solvation structures than DPE + LiFSI. Furthermore, the quantum mechanical features of the Li+ solvation structures in DPE + 1.8 M LiFSI, FEME + 1.8 M LiFSI, and EC/DEC + 1 M LiPF6 electrolytes are analyzed in detail using DFT calculations. We anticipate that this study will provide valuable insights into the Li+ solvation structures in DPE, FEME, and EC/DEC electrolytes, where the ether-based electrolytes exhibit closely similar properties.
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This content will become publicly available on November 6, 2026
Incorporating Solvation Effects in Oxidative Stability Predictions of Battery Electrolytes
Accurately predicting the oxidative stability of battery electrolytes is crucial for improving our understanding of high-voltage behavior and rational design of next-generation systems employing novel chemistries. However, commonly applied strategies based on evaluation of orbital occupancies of isolated molecules within density functional theory techniques neglect many-body solvation and interfacial effects that govern the electro-thermodynamics in real systems. Here, we advance a computational methodology that integrates molecular dynamics sampling of local solvation environments with explicit vertical ionization potential (IP) calculations to account for such effects. Our approach allows for both statistical accounting of IP distributions as well as prediction of the oxidized species (e.g., solvent vs anion decomposition). Application of this method to a matrix of electrolytes based on common lithium salts and solvents yields more detailed conclusions that often disagree with those gained through conventional calculations. We also demonstrate that this methodology can capture variations in IP associated with increased salt concentrations as well as the speciation and stability next to electrified model interfaces. This work offers a comprehensive accounting of the microscopic factors and electronic structure considerations that stabilize molecules and their unique solvation environment in modern electrochemical systems.
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- Award ID(s):
- 2145144
- PAR ID:
- 10652232
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- The Journal of Physical Chemistry Letters
- Volume:
- 16
- Issue:
- 44
- ISSN:
- 1948-7185
- Page Range / eLocation ID:
- 11398 to 11404
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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