Development and application of a semi-detailed model for lithium-Ion battery thermal runaway chemistry

To overcome the disadvantages of detailed methodologies and existing simple methodologies for modeling lithium-ion battery thermal runaway chemistry, a semi-detailed model has been developed in the present work. This is important for mitigating battery thermal runaway. The semi-detailed model contains two parts: a 'global part' and an 'elementary reaction mechanism part'. The thermal kinetics parameters of a recently published model are improved so that it can be selected for the 'global part' to model NCM811 (LiNi0.8Co0.1Mn0.1O2), NCM622 (LiNi0.6Co0.2Mn0.2O2), and NCM532 (LiNi0.5Co0.3Mn0.2O2). Temperature and heat release evolutions during battery thermal runaway can be obtained from the simulation of the 'global part'. In the 'elementary reaction mechanism part', 53 reactions with frequency factors and activation energies have been proposed and adopted for describing flammable gas formation, lithium-ion consumption, gas phase interaction, and lithium-ion gas interaction during battery thermal runway. Detailed processes for coupling the 'global part' and the 'elementary reaction mechanism part' as well as solving the 53 reactions are developed, which is the major novelty of this work. Through the coupling of the two parts, chemical venting gas species generation and lithium-ion consumption during the transient thermal runaway process of an NCM811PC (LiNi0.8Co0.1Mn0.1O2 poly-crystalline) pouch cell with nail penetration were calculated and compared with available experimental data in the literature. The comparison shows that the semi-detailed model can give correct species trends, indicating the two parts and their coupling in the semi-detailed model of the present work are reliable. The simulation results with transient venting gas chemical species provide useful insights for stopping or delaying battery thermal runaway.