Thermal runaway in lithium-ion battery cells poses significant safety risks due to rapid heat generation and potential thermal propagation within a battery system. This study investigates the total heat released and the fraction of energy contained in gas and particles ejected during thermal runaway using a purpose-built calorimeter setup. The results show that the fraction of ejected heat is significantly influenced by the state of charge (SOC) and cell mass loss. Notably, the non-ejected heat was higher at 75% SOC compared to 100% SOC due to higher fraction of ejected heat at high SOC. This will have implications in thermal propagation scenarios. Additionally, the study compares the results with accelerating rate calorimetry tests, highlighting the limitations of the latter in measuring the total heat released during thermal runaway. The findings show the need for comprehensive testing methods that can improve thermal management and safety in battery systems.

Fluorinated substances are widely used in the different components of the lithium-ion battery cell, such as electrode binders, electrolyte, additives and separator materials. To date, most studies regarding the fluorinated contaminations from lithium-ion battery fires are focused on the gases formed, whereas the solids produced are not as well characterized. Here, we present an experimental study investigating the occurrence of per- and polyfluoroalkyl substances, in soot and particulates formed after thermal runaway in lithium-ion battery cells. Per- and polyfluoroalkyl substances were detected in every battery cell test performed in this study. The concentration of per- and polyfluoroalkyl substances ranged between 20 to 130 ng/gsoot. Extrapolation of data gives an estimated release of 10 to 60 µg of per- and polyfluoroalkyl substances per kg battery cells. Among the 22 per- and polyfluoroalkyl substances analyzed, perfluorobutanesulfonic acid and perfluorobutanoic acid were found in the highest concentrations for all samples. Interestingly, perfluorooctanoic acid was detected in all tests, in concentrations ranging between 0.05 to 0.62 ng/gsoot. These findings are of importance not only for the purpose of decontamination after thermal runaway events, but also when it comes to the lithium-ion battery recycling processes. 

The report presents a review of current literature, testing and modelling in support of guidelines how to address current risks with batteries from e-bikes and e-scooters. It has been shown that a fire initiated in a battery module can have an exceedingly fast fire growth and may pose new risks that cannot be accommodated within the current design methodology. The data from measurements indicated that the fire growth in terms of heat release rates may be faster than the currently used models. The tests present typical heat release rates from open fire tests in combination with release of toxic and flammable gases from cells and modules. Using accelerating rate calorimetry, conditions when single cells enter a thermal runaway could be determined. Utilizing the information from the testing, simulations of a module were performed to investigate the effect of mass ejection from cells during the thermal runaway, complementing the knowledge how the thermal propagation was disrupted in the module.

The information gathered from literature, testing and modelling was used to propose a design fire. Although, the fully developed fire is no more severe than a usual fire the very fast fire growth rate may cause deflagration type events that compromises the fire resistance properties.

Note that while the proposals are general, they mainly influence possible future dwellings thus dissemination of current risks to the public is necessary. Some of the recommendations can be summarized as follows; Being mindful of batteries and where to charge battery modules; Keep a watch on the health of your batteries, which includes but are not limited to observing if they have been damaged in any way or become unusually hot during operation and perhaps most importantly do not charge batteries where escape routes can be compromised.   

Lithium-ion battery safety is a topic of large importance, and testing is associated with large costs. Safety evaluation is therefore needed also at an early stage in cell design and development, in order to evaluate potential short-comings or to screen large platforms of materials and cells. Previous thermal runaway tests on lab-scale cells have, however, indicated differences in heat release and temperature increase as compared to commercial cells. On the other hand, these could also vary between different commercial cells due to differences in cell materials, size, format, and design. In this work, thermal runaway characteristics of industrial-scale cells are compared against each other as well as with lab-scale cells. Tests were performed on lab-scale coin cells and five different industrial-scale cells ranging from 5 to 157 Ah, covering different cell formats and materials. The coin cells were built using electrodes and separator extracted from one of the industrial-scale cells. The results show that the thermal runaway will be less violent and reach lower maximum temperatures using lab-scale cells, depending on the lower proportion of active materials as compared to inactive components. It is also shown that the ratio between cell capacity and heat capacity is a useful indicator for the comparability of thermal runaway scenarios. This ratio varies considerably for small cells, but not so much for different commercial cells. The data available suggests that a cell capacity of at least 1 Ah is needed to achieve a good comparison of the thermal runaway scenario with larger commercial cells.

This report includes the Proceedings of the 8th International Conference on Fires in Vehicles –FIVE 2025, held in Reykjavik, Iceland, April 7-8, 2025. The Proceedings includes 17 papers given by speakers in 9 different sessions: EV Guidelines, Battery Fires, Safety of Alternative Fuels, EV Fire Suppression, Car Park Fires, Fire Development, Fire Incidents and 2 Keynote sessions. Each day was opened by invited keynote speakers addressing broad topics of interest.In addition, 11 extended abstracts are included in the proceedings presenting posters exhibited at the conference.No responsibility is assumed by the Publisher for any use or operations of any methods, products, instructions or ideas contained in the material herein. The views expressed in the papers are those of the authors and not necessarily those of RISE Research Institutes of Sweden

Lithium-ion batteries are used in a wide range of applications, from small consumer products and electric vehicles to large stationary energy storage systems and electrically propelled ships. The increased use of lithium-ion batteries for energy storage systems has put an emphasis on battery safety. Upon battery failure, e.g. due to external heating or an internal short circuit, material decomposition and accelerated exothermic reactions may result in a thermal runaway. Thermal runaway in lithium-ion batteries generally means the production of large amounts of flammable gas which poses an explosion risk. To mitigate explosions and to enable safety evaluation and design of appropriate and rightfully dimensioned safety features, such as ventilation, the gas release characteristics are of great importance. In this paper, gas characteristics from thermal runaway in lithium-ion battery cells are evaluated. The gas characteristics, such as the gas production rate, gas volumes and chemical composition are evaluated for more than 80 battery cell tests. The chemical composition was analyzed using multiple techniques to assess the consistency of the obtained data. The main components formed during thermal runaway are carbon dioxide, carbon monoxide, hydrogen and various hydrocarbons. The total volume of gas produced, normalized to the rated electrical energy of the cell, varies typically between 0.1 and 0.7 L/Wh. Results show that the cell type, cell size, state-of-charge and even the thermal runaway trigger method influence the gas characteristics. Furthermore, explosion mitigation strategies for large battery systems focusing on ventilation and ventilation strategies are presented. Finally, safety aspects related to the battery cell and system design, such as choice of cell chemistry, thermal barriers, and routes for safe evacuation of thermal runaway vent gas are discussed.

Lithium-ion batteries are used in a wide range of applications, from small consumer products and electric vehicles to large stationary energy storage systems and electrically propelled ships. The increased use of lithium-ion batteries for energy storage systems has put an emphasis on battery safety. Upon battery failure, e.g. due to external heating or an internal short circuit, material decomposition and accelerated exothermic reactions may result in a thermal runaway. Thermal runaway in lithium-ion batteries generally means the production of large amounts of flammable gas which poses an explosion risk. To mitigate explosions and to enable safety evaluation and design of appropriate and rightfully dimensioned safety features, such as ventilation, the gas release characteristics are of great importance. In this paper, gas characteristics from thermal runaway in lithium-ion battery cells are evaluated. The gas characteristics, such as the gas production rate, gas volumes and chemical composition are evaluated for more than 80 battery cell tests. The chemical composition was analyzed using multiple techniques to assess the consistency of the obtained data. The main components formed during thermal runaway are carbon dioxide, carbon monoxide, hydrogen and various hydrocarbons. The total volume of gas produced, normalized to the rated electrical energy of the cell, varies typically between 0.1 and 0.7 L/Wh. Results show that the cell type, cell size, state-of-charge and even the thermal runaway trigger method influence the gas characteristics. Furthermore, explosion mitigation strategies for large battery systems focusing on ventilation and ventilation strategies are presented. Finally, safety aspects related to the battery cell and system design, such as choice of cell chemistry, thermal barriers, and routes for safe evacuation of thermal runaway vent gas are discussed.

Accurate measurement of the heat release from a battery fire is vital for risk management, product development and construction of accurate models. Oxygen consumption calorimetry is the most common method for heat release measurements in experimental fire tests. The strength of the method is that it can be applied to unknown compositions of fuel with sufficient accuracy. Despite that this method is used to estimate heat release from battery fires, the method is subject to discussion. In this work, the method is studied in-depth, and potential errors are structured and quantified. Uncertainties associated with self-generated oxygen and internal heat generation, total gas release from the battery and impact on the heat release calculations, as well as the assumed E-factor (i.e., heat release per unit mass of oxygen consumed), are thoroughly discussed. For a Li-ion battery fire, it is concluded that oxygen consumption calorimetry will exclude internal heat generation and underestimate the total heat released from the external flaming fire by up to 10 %. In addition, high rate of combustion reactions can result in that the measured peak heat release rate is underestimated much more, up to 100 %. 

In the IEA Global EV Outlook 2022, Norway, Iceland, and Sweden were reported to have the highest electric car shares of the new car market: 86%, 72% and 43%, respectively. Electrification of the transport sector has multiple benefits but has also raised some concerns. Fires in electric vehicles are reported almost daily in the media and social media channels. However, fires starting in an electric vehicle traction battery (i.e., lithium-ion battery) are rare. If the traction battery catches fire, it can be difficult to extinguish since the battery pack in an electric vehicle is generally well protected and difficult to reach. To cool the battery cells, firefighters must prolong the application duration of suppression agent. This results in the use of large amounts of water, that potentially could carry pollutants into the environment. In this work, the analysis of extinguishing water from passenger vehicle fires are reported. Three large-scale vehicle fire tests were performed, the vehicles used were both conventional petrol fuelled and battery electric. Tests were performed indoors at RISE, Borås and the test setup allowed analysis of both combustion gases and extinguishing water. Results show that all analysed extinguishing water was highly contaminated. Additionally, the ecotoxicity analysis of the extinguishing water showed that the extinguishing water was highly toxic towards the tested aquatic species, independent of the traction energy of the vehicle.