The solvation structure, transport properties and reduction behavior of carbonate-based electrolytes of lithium-ion batteries† † Electronic supplementary information (ESI) available: The MD simulation box, detailed solvation structure population, linear diffusion behavior, sample trajectories, optimized solvation structures, binding energy decomposition, experimental measurement raw data, ionic conductivity calculating using conventional method, validation of the force field, and force field data of EC, EMC, FEC, and LiPF6. See DOI: 10.1039/d1sc04265c

ABSTRACT: Despite the extensive employment of binary/ternary mixed-carbonate electrolytes (MCEs) for Li-ion batteries, the role of each ingredient with regards to the solvation structure, transport properties, and reduction behavior is not fully understood. Herein, we report the atomistic modeling and transport property measurements of the Gen2 (1.2 M LiPF6 in ethylene carbonate (EC) and ethyl methyl carbonate (EMC)) and EC-base (1.2 M LiPF6 in EC) electrolytes, as well as their mixtures with 10 mol% fluoroethylene carbonate (FEC). Due to the mixing of cyclic and linear carbonates, the Gen2 electrolyte is found to have a 60% lower ion dissociation rate and a 44% faster Li+ self-diffusion rate than the EC-base electrolyte, while the total ionic conductivities are similar. Moreover, we propose for the first time the anion–solvent exchange mechanism in MCEs with identified energetic and electrostatic origins. For electrolytes with additive, up to 25% FEC coordinates with Li+, which exhibits a preferential reduction that helps passivate the anode and facilitates an improved solid electrolyte interphase. The work provides a coherent computational framework for evaluating mixed electrolyte systems. The different roles of the anion, cyclic and linear carbonates, and additive in mixed-carbonate electrolytes are revealed. The anion–solvent exchange mechanism and factors influencing the solid electrolyte interphase (SEI) formation are deciphered.

SUBMITTER: Hou T 

PROVIDER: S-EPMC8597828 | biostudies-literature |

REPOSITORIES: biostudies-literature