Extensive atomistic molecular dynamics simulations were conducted using the APPLE&P polarizable force field for ethylene carbonate (EC): dimethyl carbonate (DMC)/ [Li][PF6] electrolyte mixed with 1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide [Pyr14][TFSI] ionic liquid (IL). Systems with different IL concentrations were simulated at room temperature to study the local coordination of ions and ion transport properties. Ion self-diffusion coefficients (Di), ionic conductivity, transference and transport numbers were analyzed and compared to experimental data. Results showed a uniform decrease of Di with increasing IL percentage which is due to the viscosity effect. The system with 10% weight fraction of [Pyr14][TFSI] showed an optimum of ionic conductivity, and also a better electrochemical and thermal stability. Our analysis showed that adding IL changes the ion clustering pattern in the electrolyte from Li(EC)3(DMC)1 to Li(EC)2(DMC)1(TFSI)1 to Li(TFSI)n. Analysis of different contributions to ionic conductivity allowed us to identify the most important ionic correlations that affect the total ion transport and specifically Li transport in these systems.

Ion transport properties in mixed ionic liquid/carbonate electrolytes for Li-ion batteries

255th National Meeting (2018)

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