Fire fighting for lithium battery fires

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:

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.

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.

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:

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.

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.