Algorithm for Theoretical Assessment of the Electrochemical Stability of Electrolytes in Lithium-Ion Batteries by the Example of LiBF4 in the EC/DMC Mixture

The resistance of electrolytes to oxidative decomposition on the positive electrode surface is one of barriers that complicate the development of rechargeable batteries with the high energy density. The electrochemical stability of electrolytes is directly related to the composition and structure of solvate complexes formed at salt dissolution. Based on a combination of methods of molecular dynamics and quantum chemistry it is possible to develop the algorithm for theoretical assessment of the electrolyte resistance to anodic oxidation as a function of its composition. This algorithm can be used for selecting versions among the studied mixtures of solvents and lithium salts with the aim of developing new electrolytes stable up to 5 and 6 V. In this study, the methods of classical molecular dynamics and quantum chemistry are used for finding the structure of solvate complexes formed in LiBF4 solutions in the binary mixture ethylene carbonate (EC)/dimethylcarbonate (DMC). The quantum-chemical assessment of the thermodynamic and oxidation stability of solvate complexes makes it possible to find which complexes make the most considerable contribution to the electrochemical stability of the electrolyte system and calculate the additive potential of electrolyte oxidation.