Thermal runaway is a major concern for lithium-ion batteries in electric vehicles. A manufacturing fault or unusual operating conditions may lead to this event. Starting from a single battery cell, more cells may be triggered into thermal runaway, and the battery pack may be destroyed. To prevent this from happening, safety solutions need to be evaluated. Physical testing is an effective, yet costly, method to assessing battery safety performance. As such, the potential of a numerical tool, which can cut costs and reduce product development times, is investigated in terms of capturing a battery module’s tolerance to a single cell failure. A 3D-FE model of a battery module was built, using a commercial software, to study thermal runaway propagation. The model assumes that when the cell jelly roll reaches a critical value, thermal runaway occurs. This approach was considered to study the module’s tolerance to a single cell failure, which was in reasonable agreement with what had been observed in full-scale experiments. In addition, quantitative sensitivity study on the i) model input parameters, ii) model space, and iii) time resolutions on the computed start time instant and time duration of thermal runaway were performed. The critical temperature was found to have the greatest influence on thermal runaway propagation. The specific heat capacity of jelly roll was found to significantly impact the thermal runaway time duration. The multi-physics model for battery thermal propagation is promising and worth to be applied with care for designing safer batteries in combination with physical testing.

Fire safety of ships is a key issue as evacuation and extinguishment is more difficult at sea than it would be on land. There is therefore a long tradition and regulations in place to maintain the fire safety of ships. The current shift to more sustainable transport solutions has now led to the introduction of lithium-ion batteries for ship propulsion. These can offer significant benefits in terms of reducing greenhouse gas and particulate matter emissions. They also introduce new risks, however. When damaged, li-ion batteries may go into thermal runaway, a state that produces significant amounts of heat combined with flammable and toxic gas. This is a challenge, and safety is one of the key questions asked when introducing battery propulsion at sea. Extinguishment of battery fires is a piece of the puzzle when it comes to enabling safe battery propulsion at sea. Fire suppression systems are used today for such applications, yet no standard test method exists to evaluate their performance. This work proposes an approach that may be used to evaluate such systems and that can be used as input towards the development of a test method. Specifically, a test method aimed at evaluating the performance of fire suppression system under critical battery failures and at lowering the risk for module-to-module propagation. The test method designed here performed well and sustained the 18 tests that were done. Overall, repeatable test conditions were obtained that allowed for the performance of fire suppression systems to be investigated. All fire extinguishing systems had a positive impact in some position but not all points and it was not possible to draw any conclusion on their ability to mitigate the risk for module-to-module propagation. The tests showed that mitigating this can be possible with careful design of systems and perhaps combinations of different means.

Over the last decade, the electric vehicle (EV) has significantly changed the car industry globally, driven by the fast development of Li-ion battery technology. However, the fire risk and hazard associated with this type of high-energy battery has become a major safety concern for EVs. This review focuses on the latest fire-safety issues of EVs related to thermal runaway and fire in Li-ion batteries. Thermal runaway or fire can occur as a result of extreme abuse conditions that may be the result of the faulty operation or traffic accidents. Failure of the battery may then be accompanied by the release of toxic gas, fire, jet flames, and explosion. This paper is devoted to reviewing the battery fire in battery EVs, hybrid EVs, and electric buses to provide a qualitative understanding of the fire risk and hazards associated with battery powered EVs. In addition, important battery fire characteristics involved in various EV fire scenarios, obtained through testing, are analysed. The tested peak heat release rate (PHHR in MW) varies with the energy capacity of LIBs (EB in Wh) crossing different scales as PHRR=2EB0.6. For the full-scale EV fire test, limited data have revealed that the heat release and hazard of an EV fire are comparable to that of a fossil-fuelled vehicle fire. Once the onboard battery involved in fire, there is a greater difficulty in suppressing EV fires, because the burning battery pack inside is inaccessible to externally applied suppressant and can re-ignite without sufficient cooling. As a result, an excessive amount of suppression agent is needed to cool the battery, extinguish the fire, and prevent reignition. By addressing these concerns, this review aims to aid researchers and industries working with batteries, EVs and fire safety engineering, to encourage active research collaborations, and attract future research and development on improving the overall safety of future EVs. Only then will society achieve the same comfort level for EVs as they have for conventional vehicles. 

The original version of this article unfortunately contained an incorrect unit of PHRR for Eq. (3), which appears in abstract and conclusion, and an incorrect version of Fig. 23. (Figure presented

The demand for lithium-ion battery powered road vehicles continues toincrease around the world. As more of these become operational across the globe,their involvement in traffic accidents and incidents is likely to rise. This can damagethe lithium-ion battery and subsequently pose a threat to occupants and respondersas well as those involved in vehicle recovery and salvage operations. The project thispaper is based on aimed to alleviate such concerns. To provide a basis for fire safetysystems to be applied to damaged EVs, hazards have been identified and means forpreventing and controlling lithium-ion battery fires, including preventive measuresduring workshop and salvage activities were studied. Tests were also performed withfixed fire suppression systems applying suppressant inside traction batteries whichshowed to improve their safety.

This investigation studied the utilization of intumescent thermal resistive mats to provide surface protection to the core natural fibre-reinforced Elium® composite structural integrity. The intumescent mats contained flame retardant (FR) i.e. expandable graphite (EG) with four different expansion ratios and alumina trihydrate (ATH). All natural fibre thermoplastic composites were fabricated using a resin infusion technique. The impact of char thickness and chemical compositions on the flammability and smoke properties was investigated. It was found that surface protection significantly reduced the peak heat release rate, total smoke release, smoke extinction area and CO2 yield, and substantially enhanced UL-94 rating, time to ignition and residual char network, depending on the EG exfoliation ratio, ATH and mineral wool fibre. The glass transition temperature increased for the FR composites containing EG with lower expansion ratio. Inclusion of intumescent mats increased the strength of the composites while it had a negative effect on the modulus. 

The ongoing shift to electromobility has identified new risk areas. Fires involving electric vehicles have attracted considerable media attention and a strong concern related to burning electric vehicles containing lithium-ion batteries is the release of toxic gas. This report includes a literature review, vehicle fire tests, battery fire tests and simulations to gather and present data on gas and heat release during fire in electric vehicles. One electrical vehicle and one conventional vehicle in the full-scale fire tests were of the same model from the same manufacturer which enable a good comparison between the powertrains. Peak heat release rate and total heat release are affected by the fire scenario and vehicle model, but not significantly on the powertrain. Regarding toxic gases, hydrogen fluoride represents the largest difference between electric vehicles and conventional vehicles, but when smoke from vehicle fire is inhaled there are several acute toxic gases present regardless of the type of vehicle burning. Except hydrogen fluoride, there are also some specific metals present in the smoke that constitutes a large difference between the powertrains.

The demand for lithium-ion battery powered road vehicles continues to increase around the world. As more of these become operational across the globe, their involvement in traffic accidents and fire incidents is likely to rise. This can damage the lithium-ion battery and subsequently pose a threat to occupants and responders as well as those involved in post-crash operations. There are many different types of lithium-ion batteries, with different packaging and chemistries but also variations in how they are integrated into modern vehicles. To use lithium-ion batteries safely means to keep the cells within a defined voltage and temperature window. These limits can be exceeded as a result of crash or fault conditions. This report provides background information regarding lithium-ion batteries and battery pack integration in vehicles. Fire hazards are identified and means for preventing and controlling them are presented. The possibility of fixed fire suppression and detection systems in electric vehicles is discussed.

The work involves fabrication of natural fibre/Elium® composites using resin infusion technique. The jute fabrics were treated using phosphorus-carbon based flame retardant (FR) agent, a phosphonate solution and graphene nano-platelet (GnP), followed by resin infusion, to produce FR and graphene-based composites. The properties of these composites were compared with those of the Control (jute fabric/Elium®). As obtained from the cone calorimeter and Fourier transform infrared spectroscopy, the peak heat release rate reduced significantly after the FR and GnP treatments of fabrics whereas total smoke release and quantity of carbon monoxide increased with the incorporation of FR. The addition of GnP had almost no effect on carbon monoxide and carbon dioxide yield. Dynamic mechanical analysis demonstrated that coating jute fabrics with GnP particles led to an enhanced glass transition temperature by 14%. Scanning electron microscopy showed fibre pull-out locations in the tensile fracture surface of the laminates after incorporation of both fillers, which resulted in reduced tensile properties. © 2019 by the authors.

The effectiveness of ‘drencher systems’ per Resolution A.123(V) has been questioned for many years. This report presents a review of potential commercially available alternative systems and their expected performance efficiency, water consumption and estimated installation costs. Additionally, large‑scale fire tests were performed for selected systems.

Three main alternative fire-extinguishing systems were identified:

• Compressed Air Foam Systems (CAFS)
• Foam-water sprinkler and foam‑water spray systems; and
• Water curtains.

Water curtains was the least expensive system, but the areas sub‑divided by the water curtains require cargo spacing, resulting in significant yearly losses in income for a ship owner. Furthermore, water curtains were de-selected since they cannot replace a conventional fire-extinguishing system.

The installation cost for the selected CAFS was very high and it gave limited fire suppression in the large‑scale fire tests, probably due to the limited discharge density of 2.4 mm/min.

The system per MSC.1/Circ.1430 (10 mm/min) had superior performance while the system per Resolution A.123(V) (5 mm/min) and the foam‑water spray system (6.5 mm/min + foam) limited the fire size to some degrees. However, for a potential spill fire scenario, improvements of foam could be relevant.

Foam injection could be an alternative, but no new system was recommended to be required.