International audienceSafety issues pertaining to Li-ion batteries justify intensive testing all along their value chain. However, progress in scientific knowledge regarding lithium based battery failure modes, as well as remarkable technologic breakthroughs in computing science, now allow for development and use of prediction tools to assist designers in developing safer batteries. Subsequently, this paper offers a review of significant modeling works performed in the area with a focus on the characterization of the thermal runaway hazard and their relating triggering events. Progress made in models aiming at integrating battery ageing effect and related physics is also discussed, as well as the strong interaction with modeling-focused use of testing, and the main achievements obtained towards marketing safer systems. Current limitations and new challenges or opportunities that are expected to shape future modeling activity are also put in perspective. According to market trends, it is anticipated that safety may still act as a restraint in the search for acceptable compromise with overall performance and cost of lithium-ion based and post lithium-ion rechargeable batteries of the future. In that context, high-throughput prediction tools capable of screening adequate new components properties allowing access to both functional and safety related aspects are highly desirable

International audienceTo better rule out the complex fire risk related to large format lithium ion cells, a detailed and systematic evaluation, both at component and cell levels, could be an invaluable milestone. Therefore, combustion analysis was conducted for major single organic solvents and their mixtures used in lithium ion battery technology, both in oxygen rich and lean environments using a Tewarson calorimeter. Well controlled test conditions have enabled the determination of key parameters governing the fire induced hazards such as flash point, ease of ignition, heat release rate, effective heat of combustion, specific mass loss rate, as well as the assessment of fire induced toxicity. Moreover, a rule of thumb for the screening of new solvents including the safety perspective such as the Boie correlation and N-factor were introduced for predicting the heat of combustion and combustion kinetics, respectively, prior to conducting any experimental work. Fire induced toxicity of single solvents and their mixtures was also briefly examined by performing toxic gas measurements

Li-ion secondary rechargeable batteries are becoming the preferred solution to store energy on board of new generation electric and hybrid vehicles or manage renewable energy in stationary applications. However, Li-ion batteries (LIBs) are still suffering limited lifetime, high cost and significant safety issues increasing their time to mass market. Thermal runaway is still nowadays considered as a major hazard of LIBs. This multiscale and multistep phenomenon originating at the microscale level potentially leads to uncontrolled fire and explosion of the battery. This work is focused on the development and validation of a 3D physical model of the LIB electro-thermal behavior nearby thermal runaway conditions. A combined modeling and experimental investigation provides a better understanding of the mechanisms leading to thermal runaway of LIBs, and of the ageing influence on this process. One major outcome of this work is also the proven fact that calendar ageing leads to a delayed onset of the cell self-heating temperature with a thermal runaway starting at a lower temperature. This is supported by computer simulations showing that the thickening of the solid electrolyte interface (SEI) hinders the diffusion of Li ions, which delays the degradation of the negative electrode and the occurrence of thermal runaway. HIGHLIGHTS  Development of an original 3D thermal runaway model including calendar ageing.  Model includes 3D thermal, 3D chemical reaction, and 0D calendar ageing sub-models. Calibration of the model for cylindrical 26650 LFP/C cells using a BTC. Validation of the model for fresh as well as 10% and 30% aged cells in oven tests.  Fresh and aged cells are compared in terms of critical temperatures under overheating 2

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The use of ionic liquids (ILs) as advanced electrolyte components in electrochemical energy-storage devices is one of the most appealing and emerging options. However, although ILs are hailed as safer and eco-friendly electrolytes, to overcome the limitations imposed by the highly volatile/combustible carbonate-based electrolytes, full-scale and precise appraisal of their overall safety levels under abuse conditions still needs to be fully addressed. With the aim of providing this level of information on the thermal and chemical stabilities, as well as actual fire hazards, herein, a detailed investigation of the short- and long-term thermal stabilities, biodegradability, and combustion behavior of various pyrrolidinium-based ILs, with different alkyl chain lengths, counteranions, and cations, as well as the effect of doping with lithium salts, is described.