Electrolyte evaporation after an electrolyte leakage in a quiescent environment: a computational fluid dynamic study

The leakage of electrolyte from battery cells is one of the most common battery failure mechanisms and may lead to the release of harmful compounds to the general population. This is due to the high volatility and toxicity of common electrolyte solvents, such as dimethyl carbonate (DMC) and diethyl carbonate (DEC). Detection and early warning systems are therefore needed, particularly in enclosed and poorly ventilated environments such as garages. In this work, a CFD-RANS evaporation and dispersion model was applied to simulate electrolyte leakage in an enclosed, non-ventilated garage, with the aim of assessing the optimal positioning of sensors for early leakage detection. Results from the garage simulations of the evaporation and dispersion of pure DMC and DEC show that the generated vapours behave as heavy gases, spreading radially within the environment and accumulating near the source. Furthermore, large environments like the one presented in this work (50.7 m³), where radial dispersion is favoured, severely limits vertical dispersion because it is obstacle-driven (i.e., the vapour cloud interacts with walls earlier in smaller environments). A comparison between a simplified single-component evaporation approach and a full electrolyte approach was performed. The full electrolyte evaporation scenario predicted that dangerous concentrations of DMC that could lead to irreversible health effects (i.e., Protection Action Criteria, PAC-2 = 120 ppm) may be reached at 15 cm from the ground at 45 minutes after leakage, while the pure DMC scenario predicted that PAC-2 concentrations were reached at 15 cm at 24 minutes after leakage. Therefore, the simplified single-component approach is not able to accurately reproduce the behaviour of the full electrolyte leakage scenario.