Microscopic Factors That Dictate the Optimal Compositions of Mixed Solvent Systems for Lithium Ion Battery Applications: Revelation through a Combined Experimental and Simulation Study.

Authors

Narayan Chandra Maity, Sudipta Mitra, Ranjit Biswas

Published in

The journal of physical chemistry. B. Jun 25, 2026. Epub Jun 25, 2026.

Abstract

Optimization of the mixture composition for mixed solvent-based battery electrolyte systems and determination of the underlying governing factors are critical for the advancement of high-performance lithium-ion batteries (LIBs). In this study, we have made an attempt to identify the factors that dictate the optimal composition of a representative binary solvent mixture and electrolyte system containing 1 M LiTFSI in a mixture of ethylene carbonate (EC) and adiponitrile (ADN). For this, we have performed differential scanning calorimetry (DSC) and dielectric relaxation spectroscopy (DRS) measurements at different EC mole fractions (X_EC). Subsequently, the molecular-level aspects related to composition optimization have been explored by examining the solvation structure, ion transport, and ion-ion dynamical correlations via molecular dynamics (MD) simulations. DSC measurements reveal a nonmonotonic dependence of the melting temperature (T_m) on solvent composition, with a minimum value of 250 K at X_EC = 0.6. Furthermore, both the ionic conductivity (σ) and average DR time (τ_DR) exhibit composition-dependent inflection points between X_EC = 0.4 and 0.6 in the temperature range of 298 K-323 K. MD simulations have revealed identical self-diffusivities of cations and anions at X_EC = 0.6, while both EC and ADN maintain a balanced presence inside the Li⁺ solvation shell. Moreover, the composition dependence of the solvent coordination number inside the Li⁺ solvation shell correlates with the experimentally observed crossovers in σ and τ_DR. Notably, an optimized presence of both EC and ADN molecules inside Li⁺ solvation shell facilitates balanced ion transport with Li⁺ transference number t₊ ≈ 0.5 at X_EC = 0.6, suitable for battery operation, while simultaneously suppressing the anion-anion dynamical anticorrelation.

PMID:
42345135
Bibliographic data and abstract were imported from PubMed on 25 Jun 2026.

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