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Lithium-ionbattery performance is strongly influenced by the ionicconductivity of the electrolyte, which depends on the speed at whichLi ions migrate across the cell and relates to their solvation structure.The choice of solvent can greatly impact both the solvation and diffusivityof Li ions. In this work, we used first-principles molecular dynamicsto examine the solvation and diffusion of Li ions in the bulk organicsolvents ethylene carbonate (EC), ethyl methyl carbonate (EMC), anda mixture of EC and EMC. We found that Li ions are solvated by eithercarbonyl or ether oxygen atoms of the solvents and sometimes by thePF6–anion. Li+prefers a tetrahedrally coordinated firstsolvation shell regardless of which species are involved, with thespecific preferred solvation structure dependent on the organic solvent.In addition, we calculated Li diffusion coefficients in each electrolyte,finding slightly larger diffusivities in the linear carbonate EMCcompared to the cyclic carbonate EC. The magnitude of the diffusioncoefficient correlates with the strength of Li+solvation.Corresponding analysis for the PF6–anion shows greater diffusivity associatedwith a weakly bound, poorly defined first solvation shell. These resultscan be used to aid in the design of new electrolytes to improve Li-ionbattery performance. [ABSTRACT FROM AUTHOR]