Development and Validation of a Reduced Chemical Kinetic Mechanism of Dimethyl Carbonate and Ethylene Carbonate 2024-01-2085

With the rapid development of electric vehicles, the demands for lithium-ion batteries and advanced battery technologies are growing. Today, lithium-ion batteries mainly use liquid electrolytes, containing organic compounds such as dimethyl carbonate and ethylene carbonate as solvents for the lithium salts. However, when thermal runaway occurs, the electrolyte decomposes, venting combustible gases that could readily be ignited when mixed with air and leading to pronounced heat release from the combustion of the mixture. So far, the chemical behavior of electrolytes during thermal runaway in lithium-ion batteries is not comprehensively understood. Well-validated compact chemical kinetic mechanisms of the electrolyte components are required to describe this process in CFD simulations. In this work, submechanisms of dimethyl carbonate and ethylene carbonate were developed and adopted in the Ansys Model Fuel Library (MFL). Further improvements were made to enhance the kinetic consistency between these submechanisms and the base mechanism of the MFL. These mechanisms were validated using recently published experimental datasets over a wide range of conditions and show satisfactory performance. Analysis of the simulated results has revealed the important reaction pathways in the decomposition of dimethyl carbonate and ethylene carbonate. The species involved in the most critical pathways were selected as key species in the subsequent mechanism reduction using Ansys Reaction Workbench. Multiple mechanism reduction approaches were applied in combination to reduce the mechanism described here to 38 species and 177 reactions. This mechanism is ready to be used in CFD simulation.