Advanced abuse modelling of Li-ion cells – A novel description of cell pressurisation and simmering reactions

Abstract

Thermal runaway (TR) is a significant safety concern for Li-ion batteries (LIBs), which, through computational modelling can be better understood. However, TR models for LIBs lack a proper representation of the build-up of pressure inside a cell under abuse, which is integral to predicting cell venting. Here, an advanced abuse model (AAM) is developed and compared to a classical TR model, considering a lithium iron phosphate (LFP) cell case study. The AAM accounts for two additional features: 1) venting, with a novel description of the internal cell pressure governed by the bubble point of the electrolyte/decomposition-gas mixture, and 2) simmering reactions. The novel bubble pressure assumption is validated against experimental data, and we show that the AAM significantly improves the predictions of time to TR and of temperatures after TR. Further, it is shown that there is significant uncertainty in the parameters defining the decomposition reactions for LFP cells. Importantly, cell pressurisation is most dependent on the gases released by the solid electrolyte interphase reaction, and venting is dependent on cell burst pressure and reaction activation energies. The AAM is essential for accurate abuse modelling, due to its improved temperature predictions, and considerably enhances the LIB TR field of study.

Zero fire battery concept: water-in-battery

“…The caloric value of the battery thermal runaway can be calculated by heat equations. 19 It is based on the equation of specic heat release (Joules per gram of material), the volume of specic contents, and reaction parameters, determined by the decomposition factor and activation energy of the materials comprising the battery. Based on these values, the total heat release is calculated from the reactions of the positive and negative solvent reactions, and the decomposition reactions of the solid electrolyte interface and electrolyte.…”

“…An 18650 type of LIB cell with 3.7 V and 2.6 Ah, and had a heat release of about 17.9 kJ to 26.2 kJ. [19][20][21] To standardize the theoretical amount of the required water, the maximum energy that can be generated in the short circuit is converted into heat energy, which can raise the temperature of the water. The heat absorbance of the water was calculated by multiplying the specic heat capacity of the water (4.18 J g À1 C À1 ), temperature changes from room temperature (25 C) to the boiling point of water (100 C), and the amount of water.…”

“…The loss of capacity was lower in the WiB than in the normal LIB cells due to the heat management capacity of the water. The water prevented the loss of lithium and active materials in the WiB that maintained the capacity over cycles,29,30 while avoiding the increase of internal resistance for power 19. Fig.2(c) shows a comparison of the state-of-health of a battery over a cycle to compare the capacity degradation ratio with the cycle and type of battery.…”

Investigation of the Impact of Flow of Vented Gas on Propagation of Thermal Runaway in a Li-Ion Battery Pack

“…technique have been reported for studying onset and evolution of thermal runaway venting in 18650 Li-ion cells. [19][20][21] The composition of vented gases is important for understanding post-venting events such as combustion and thermal advection, and has been reported in a number of papers. Measurements of total gas emission volumes, gas emission rates and amount of HF and CO 2 emissions during venting have been presented.…”

A coupled conjugate heat transfer and CFD model for the thermal runaway evolution and jet fire of 18650 lithium-ion battery under thermal abuse

“…Ostanek et al [37] simulated onset and evolution of LIB TR using a coupled thermal and venting lumped model, and the flow parameter through the vent was modeled by compressible flow equations after vent opening. Bugryniec et al [39] proposed an abuse model to investigate cell pressurization and simmering reactions of LIBs, and achieved similar prediction of the pressure accumulation in comparison with a classical TR model [35,36]. Mao et al [38] developed a lumped model for the characteristics of the 18650-type LIB jet flow and fire dynamics.…”