CFD Analysis of Cathode Chemistry, State-of-Charge and CO2-Enriched Environment on Lithium-Ion Battery Fire Characteristics

This study presents a 2D axisymmetric Computational Fluid Dynamics (CFD) model, developed in the open-source OpenFOAM framework, to investigate the venting and turbulent combustion of cylindrical lithium-ion battery cells during thermal runaway (TR). Venting characteristics, including mass flow rate, gas composition, gas quantity, and release temperature, are parameterized from established literature. The model systematically examines the effects of cathode chemistry (LCO, NMC, LFP, NCA), state of charge (25%, 50%, and 100%), and CO₂-enriched suppression atmospheres (0% and 45% by volume) on battery fire. To achieve high computational efficiency without sacrificing predictive accuracy, a surrogate gas species is introduced that faithfully reproduces the thermophysical and combustion properties of the multicomponent battery vent gas mixture. Simulation results demonstrate that a 45% CO₂ volumetric concentration substantially reduces peak flame temperature across all chemistries and SOC levels. However, suppression efficacy varies markedly with cell type: NCA, LCO and NMC cells exhibit strong thermal suppression, whereas LFP cells show significantly weaker response due to their slower venting rates, lower total gas release, reduced heat of combustion, and higher heat capacity of the ejected gases. These findings underscore the critical dependence of CO₂-based fire suppression performance on battery chemistry and state of charge, revealing limitations of conventional total-flooding CO₂ systems, particularly against persistent LFP fires. The model is publicly released on GitHub, enabling reproducibility and further community-driven development. This open-source, scalable framework provides a quantitative foundation for extending single-cell insights to module- and pack-level fire scenarios.