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 ($$E_{B}$$ in Wh) crossing different scales as $$PHRR = 2E_{B}^{0.6}$$. 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.

A review of battery fires in electric vehicles

A review on recent progress, challenges and perspective of battery thermal management system

A perspective on sustainable energy materials for lithium batteries

The evolving global landscape for electrical distribution and use created a need area for energy storage systems (ESS), making them among the fastest growing electrical power system products. A key element in any energy storage system is the capability to monitor, control, and optimize performance of an individual or multiple battery modules in an energy storage system and the ability to control the disconnection of the module(s) from the system in the event of abnormal conditions. This management scheme is known as “battery management system (BMS)”, which is one of the essential units in electrical equipment. BMS reacts with external events, as well with as an internal event. It is used to improve the battery performance with proper safety measures within a system. Therefore, a safe BMS is the prerequisite for operating an electrical system. This report analyzes the details of BMS for electric transportation and large-scale (stationary) energy storage. The analysis includes different aspects of BMS covering testing, component, functionalities, topology, operation, architecture, and BMS safety aspects. Additionally, current related standards and codes related to BMS are also reviewed. The report investigates BMS safety aspects, battery technology, regulation needs, and offer recommendations. It further studies current gaps in respect to the safety requirements and performance requirements of BMS by focusing mainly on the electric transportation and stationary application. The report further provides a framework for developing a new standard on BMS, especially on BMS safety and operational risk. In conclusion, four main areas of (1) BMS construction, (2) Operation Parameters, (3) BMS Integration, and (4) Installation for improvement of BMS safety and performance are identified, and detailed recommendations were provided for each area. It is recommended that a technical review of the BMS be performed for transportation electrification and large-scale (stationary) applications. A comprehensive evaluation of the components, architectures, and safety risks applicable to BMS operation is also presented.

Review of Battery Management Systems (BMS) Development and Industrial Standards

Mechanism, modeling, detection, and prevention of the internal short circuit in lithium-ion batteries: Recent advances and perspectives

Smouldering wildfire in peatlands is one of the largest and longest-lasting fire phenomena on Earth, but whether peat can support a flaming fire like other surface fuels is still unclear. Our experiments demonstrate the successful piloted flaming ignition of peat soil with moisture up to 100 wt-% under external radiation, indicating that flames may rapidly spread on peatland before transitioning to a conventional smouldering peat fire. Compared with smouldering ignition, flaming ignition of peat is more difficult, requiring a higher minimum heat flux and tripling the ignition energy. The propensity for flaming increases with a drier peat and greater external heating. We also found that the flaming ignition temperature increases from 290 to 690°C as the peat moisture increases to 100 wt-%. Flames from peat soil are much weaker than those of pine needles and wood, and they eventually transition to smouldering. The heat of flaming is estimated to be 13 MJ kg−1, close to the heat of smouldering. The measured CO/CO2 ratio of flaming peat fires is less than 0.02, much smaller than 0.2 for smouldering peat fires. This research helps understand the development of peat fire and the interaction between flaming and smouldering wildland fires.

/pdf/can-peat-soil-support-a-flaming-wildfire-29zbrqd4l6.pdf

Can peat soil support a flaming wildfire

Microgravity combustion of polyethylene droplet in drop tower

Ignition of thin fuel by thermoplastic drips: An experimental study for the dripping ignition theory

The battery fire accidents frequently occur during the storage and transportation of massive Lithium-ion batteries, posing a severe threat to the energy-storage system and public safety. This work experimentally investigated the self-heating ignition of open-circuit 18650 cylindrical battery piles with the state of charge (SOC) from 30% to 100% and the cell number up to 19. As the ambient temperature increases, the self-heating ignition occurs and leads to a violent fire. The characteristic temperatures for both electrolyte leaking and thermal runaway decrease with SOC. The critical ambient temperature for self-heating ignition ranges from 135 °C to 192 °C, and it decreases with the increasing battery SOC, cell number, and pile size, which satisfies the self-ignition theory. The applied Frank-Kamenetskii analysis predicts the self-ignition ambient temperature could be lower to 30 °C for large battery piles with multiple tightly packed layers, such as those in the shipping container and warehouse. Nevertheless, creating gaps and providing effective cooling between each battery layer could effectively lower the fire risk by increasing the self-ignition ambient temperature above 125 °C. This work theoretically reveals the self-ignition characteristics of open-circuit battery piles, which could provide scientific guidelines to improve battery safety and reduce fire hazards during storage and transportation.

http://ira.lib.polyu.edu.hk/bitstream/10397/89220/1/66_JES_2020_cylinder_LIB_oven_%28preprint%29.pdf

Peiyi Sun

Papers

A review of battery fires in electric vehicles

Can peat soil support a flaming wildfire

Microgravity combustion of polyethylene droplet in drop tower

Ignition of thin fuel by thermoplastic drips: An experimental study for the dripping ignition theory

Self-heating ignition of open-circuit cylindrical Li-ion battery pile : towards fire-safe storage and transport