Experimental and numerical analysis of heat and gas generation during thermal runaway in NMC811 lithium-ion batteries under thermal abuse and inert conditions

• NMC811 cells emit more CO2, while NCA cells release more hydrocarbons during TR. • Thermal runaway of NMC/NCA cells is characterized experimentally in inert gas. • A kinetic model for combustion and gas generation of LIBs in ARC test is proposed. • NCA cells predict safety vent collapse at lower temps, showing a 10.6 % deviation. • CFD reveals CO2 generation pre-TR, while other gases emerge in the exothermic phase. Lithium-ion Batteries (LIBs) are essential to advancing renewable energy technologies; however, there are significant safety challenges, particularly concerning battery thermal runaway. Addressing these risks necessitates a deeper understanding of Battery Thermal Runaway (BTR) mechanisms, which has driven extensive research employing experimental and numerical methods. This study focuses on the thermal runaway behaviour of lithium-ion batteries, specifically those using NMC811 and NCA cathode chemistries. The thermal runaway has been experimentally characterized using an Accelerating Rate Calorimeter (ARC) in an inert environment. The experimental data have been used to validate a proposed model incorporating three-dimensional thermal modelling and thermal runaway chemical kinetics, emulating the Heat, Wait, and Seek methodology alongside ARC thermal abuse tests. The proposed model accurately predicts heat transfer phenomena within a closed-volume canister, estimating heat release, gas generation rates, and vented gas composition during thermal runaway events. These predictions are essential for enhancing safety assessments, improving battery design, and developing numerical models that predict LIB behaviour under thermal abuse conditions.