Scenario-based prediction of Li-ion batteries fire-induced toxicity
Résumé
The development of high energy Li-ion batteries with improved durability and increased safety mostly
relies on the use of newly developed electrolytes. A detailed appraisal of fire-induced thermal and
chemical threats on LiPF6- and LiFSI-based electrolytes by means of the so-called “fire propagation
apparatus” had highlighted that the salt anion was responsible for the emission of a non negligible
content of irritant gas as HF (PF6-) or HF and SO2 (FSI-). A more thorough comparative investigation of the
toxicity threat in the case of larger-size 0.4 kWh Li-ion modules was thus undertaken.
A modeling approach that consists in extrapolating the experimental data obtained from 1.3Ah
LiFePO4/graphite pouch cells under fire conditions and in using the state-of-the-art fire safety international
standards for the evaluation of fire toxicity was applied under two different real-scale simulating
scenarios. The obtained results reveal that critical thresholds are highly dependent on the nature of the
salt, LiPF6 or LiFSI, and on the cells state of charge. Hence, this approach can help define appropriate fire
safety engineering measures for a given technology (different chemistry) or application (fully charged
backup batteries or batteries subjected to deep discharge).