Fire fighting for lithium battery fires
Lithium batteries have become an integral part of our everyday working lives and are used in various areas. They supply power for smartphones, cordless screwdrivers, cars and much more. However, fires can occur during the production, use and disposal of lithium batteries. This can be caused by improper handling or quality defects, among other things. What should you do if a lithium battery fire occurs? Extinguishing attempts with conventional inert agents are usually unsuccessful. In the new DENIOS guide, you can find out how to minimise the risk of lithium battery fires and how to gain valuable time until the emergency services arrive in the event of a fire.
Risk of fire from lithium batteries
Lithium batteries harbour an increased risk of fire as they have a high energy density and generate the oxygen required for a fire themselves. The internal decomposition of a lithium battery starts at a temperature of 80 °C or higher. If a fire occurs, this reaction is known as a thermal runaway. The thermal runaway of just one cell is enough to heat up the neighbouring cells of the battery block to such an extent that a serious chain reaction occurs. Once this is set in motion, it only takes a few minutes for the battery to burn down explosively.
The fire in the lithium battery is violent and temperatures of up to 1400 °C are generated. The rise in temperature leads to an increase in pressure in the housing of the lithium battery. If this cannot escape through the pressure relief valves, the battery cell can burst, releasing a white-grey ‘mist’ of electrolytes and other cell components.
This results in a rapid spread of fire with high energy release and heavy smoke development. There is also a risk of electric shock to system components. Lithium-ion battery fires are considered very difficult to extinguish. The lithium battery contains everything needed for a fire. In addition, the housing of the lithium battery prevents the extinguishing agent from reaching the cell fire.
Preventative fire protection measures
You can take preventative measures for fire-protected storage and safe charging of lithium batteries in order to prevent the fire from spreading in the event of a fire and gain valuable time until the fire brigade arrives. Fires and explosions of lithium batteries can not only cause expensive damage to property, but in the worst case can also endanger human life. Lithium-ion batteries should never be charged in the vicinity of burning materials. In summer 2019, the VdS published a leaflet 3103 ‘Lithium batteries’, in which lithium batteries are categorised into three levels with low, medium and high power. Different safety rules apply to the respective levels. For medium and high power batteries, it is recommended that the batteries are physically separated (at least 5 metres apart) or by a fire-resistant structure. In addition to the state of charge and storage temperature, the manufacturer's safety instructions must always be observed. Charging a lithium-ion battery should always take place under supervision in order to be able to react quickly in the event of a fire.
For the safe storage and charging of lithium batteries, we offer a comprehensive range of professional safety cabinets and fire protection rooms for lithium batteries that meet the latest technical standards:
Our systems have structural fire protection on both sides as well as additional equipment for technical fire protection in order to store lithium-ion batteries for every application safely and in compliance with the law.
The WFP Li-Ion fire-protected charging compartments enable seamless monitoring of the lithium-ion batteries through integrated condition monitoring with high-quality sensors and control technology. In an emergency, an alarm is triggered, forwarded to the building management system and extinguishing or fire suppression systems are activated.
Our lithium-ion cabinets offer 90 minutes of fire protection from the inside and outside. The technical ventilation prevents heat build-up in the cabinet during the battery charging process. The safety cabinets also have integrated sensors and sound an alarm in the event of fumes or a rise in temperature.
The fire suppression system triggers automatically in the event of a fire in the cabinet and suppresses secondary fires. Thanks to the integrated transport base, you can evacuate the cabinet immediately in the event of damage to prevent consequential damage caused by extinguishing water.
Immediate measures in the event of a fire
Lithium fires pose a particular challenge in modern fire protection because they are especially difficult to control. If you detect a fire or are notified by DENIOS connect of a rise in temperature or the development of smoke gas in your safety storage cabinet or fire protection storage system, you must inform the fire brigade immediately. In the event of a fire, personal safety and saving lives always take priority over fighting the fire. In order to contain the spread of the battery fire until the emergency services arrive, DENIOS offers specialised product solutions for initial emergency measures.
Aerosol extinguishing technology
Aerosol extinguishing technology can be used as the first immediate measure to reduce the risk. This constantly operational technical system is used to suppress the fire until the fire brigade arrives and finally extinguishes the fire. It is important to note that this extinguishing technology serves as a stopgap, as lithium batteries can burn for much longer than the aerosol extinguishing system remains effective.
The extinguishing technology works in accordance with EN 15276-10 without the addition of water. As the temperature rises, the extinguishing generator effectively interrupts the chemical combustion process within 4.5 to 15 seconds, depending on the model. This technology is environmentally friendly and is not harmful to health, as it does not displace oxygen, and is recognised by the United States Environmental Protection Agency (U.S. EPA) as an official ‘HALON replacement extinguishing agent’.
Thanks to its low weight and volume and the lack of need for pipework, installation is quick and easy. In addition, the investment and follow-up costs remain low, as the aerosol extinguishing technology is maintenance-free and has a long product service life.
Both the safety storage cabinets and the fire protection rooms for lithium batteries are optionally available with a fire suppression unit with aerosol extinguishing technology.
Fire prevention products
Immediate measures include fire-fighting blankets made of special high-temperature fabric with a mineral coating on both sides, which serve to protect the surroundings in the event of battery accidents. They reduce the risk of fire spreading and contain any flames that occur. The covers are large enough to cover entire electric vehicles. They are quick and easy to use, suitable for sprinklers and extinguishing water and thus create a cooling effect.
Firefighting lithium battery fires
Only extinguishing agents with a high cooling effect should be used to fight lithium battery fires. Water is recommended as an extinguishing agent to prevent the rapid spread of fire and fumes. Larger quantities of water are able to contain and effectively fight lithium fires. One of the reasons given for this is the cooling effect, which slows down the reaction of the cells. In addition, water can help to bind the resulting fumes when highly atomised. As lithium is very reactive, extinguishing a lithium-ion battery fire harbours a number of risks. Water reacts with lithium to form hydrogen and lithium oxide, which is explosive. It is therefore essential to maintain a safe distance when extinguishing a lithium fire.
This can be explained by the structure of a traction battery:
Basically, a large traction battery consists of many smaller cells that are connected to each other. If a single cell heats up, in the worst case in the middle of the module, the neighbouring cells will inevitably also heat up. This results in a chain reaction that leads to a considerably greater release of energy. Water can help to contain this reaction due to its high cooling effect. The aim of long-term cooling is to prevent thermal runaway and thermal propagation in other cells of the lithium battery. With smaller batteries and therefore fewer cells, the external cooling can usually act directly on the reacting cells.
VdS has published a leaflet 3856 ‘Sprinkler protection of lithium batteries’, which for the first time differentiates between the energy content per storage unit (e.g. pallet) and categorises the risk according to the following table:
| Hazard Level (HL) | Risk | Energy content in kWh / storage unit |
|---|---|---|
| I | Low | >1 |
| II | Medium | 1,0 - 50 |
| III | High | >50 |
The stored energy per storage unit (e.g. pallet) should not exceed a maximum of 50 kWh. This corresponds to Hazard Level II. For storage in racking, the sprinkler system must be designed in accordance with VdS CEA 4001. Tests by the American property insurer FM-Global and the German Insurance Association (GDV) have shown that the spread of fire in the event of lithium battery fires in high-bay racking can be prevented by targeted sprinklering. However, the findings from the tests are only valid for small lithium batteries packed in cardboard boxes. The sprinkling of large battery units is nevertheless advisable, as although the fire on the individual battery is generally not extinguished, the spread to neighbouring batteries can be slowed down, if not prevented.
Follow-up measures and handling of critical batteries
Damaged lithium batteries can catch fire again even after a long period of time and should therefore be stored temporarily in suitable safety containers. DENIOS offers professional storage and transport boxes that are ideal as quarantine containers for defective lithium-ion batteries. The special containers are made of plastic, aluminium, steel or stainless steel and are available in various sizes. Depending on the model, different fire protection agents are used as filling material. For example, PyroBubbles® or Cirrux® cushions. PyroBubbles® are an extinguishing agent for solid and liquid flammable substances that has been positively tested by the MPA Dresden in accordance with DIN EN 3-7. Their melting point is 900 °C, after which they form a closed layer around the source of the fire. The extinguishing and insulating effect is activated immediately and is completely self-sufficient. Cirrux® pads made of glass fibre are non-eclectically conductive and fireproof. They are suitable for shock-absorbing packaging of lithium batteries in combination with Zarges transport boxes.
Depending on the risk assessment, performance and condition of the stored lithium-ion batteries, the quarantine boxes offer application-specific safety standards as well as effective protection against exothermic reactions through to complete control of a possible thermal runaway. The quarantine boxes prevent the escape of flames and splinters in the event of an accident. As lithium-ion batteries are classified as dangerous goods under international transport law, they are subject to the regulations for the transport of dangerous goods. This means that the hazardous goods containers must be clearly labelled with the corresponding hazardous goods symbol and the UN number of the battery. Many boxes are also suitable for subsequent transport and have the appropriate transport authorisations for defective, damaged or critically defective lithium-ion batteries. Please refer to the product details to find out which regulations are fulfilled by the respective transport boxes for lithium-ion batteries.
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The specialist information on this page has been compiled carefully and to the best of our knowledge and belief. Nevertheless, DENIOS Ltd cannot assume any warranty or liability of any kind, whether in contract, tort or otherwise, for the topicality, completeness and correctness either towards the reader or towards third parties. The use of the information and content for your own or third party purposes is therefore at your own risk. In any case, please observe the locally and currently applicable legislation.
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