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Understanding the Correlation between Lithium-Ion Diffusion and Coordination Environment in Solid Polymer Electrolytes: A Molecular Dynamics Perspective a) Inorganic and Physical Chemistry Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Bandung 40132, Indonesia. Abstract Lithium-ion diffusion in solid polymer electrolytes (SPEs) stands as a pivotal characteristic that significantly determines overall lithium-ion battery performance. This characteristic could be affected by the coordination environment of lithium-ions within the polymer matrix. However, the correlation between lithium-ion diffusion and its coordination environment inside a biopolymer-based SPEs, such as carboxymethyl chitosan (CMCS), remains understudied. Herein, molecular dynamics (MD) simulations were used to investigate the correlation. Lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) were used lithium salt in the simulated systems. All simulations were performed with GROMACS package, using the general AMBER force field (GAFF). The coordination structures around Li+ were successfully estimated using the distribution function obtained from MD simulations. The results indicate a preference for Li+ coordination with oxygen atoms, both from the CMCS polymer chains (OCMCS) and TFSI- ions (OTFSI-). The coordination number between Li+ and OCMCS decreases when the concentration of LiTFSI increases. The diffusion coefficients of Li+ varied depending on the concentration of LiTFSI and demonstrated sensitivity to the coordination structure of Li+. A high diffusion coefficient of Li+ ions was observed at low LiTFSI concentrations, where Li+ mainly coordinated with oxygen atoms from CMCS polymer chains. Keywords: Molecular dynamics, lithium-ion diffusion, lithium-ion coordination, solid polymer electrolyte, lithium battery Topic: Material Physics |
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