Fire risk associated with storage of Lithium- and Lithium-ion batteries

In this project we have been in contact with several different actors that handle and store large quantities of non-connected lithium and lithium-ion batteries. Batteries will, during their lifetime, be stored at different locations, and the locations that are considered to have the largest amount of batteries are manufacturers / distributors and recycling plants.

For operators who store large quantities of new batteries, it is common to store the batteries on pallets in conventional storage buildings secured by a water sprinkler system. Based on information from the plants we have been in contact with, we consider the fire risk to be about the same as an ordinary warehouse. Factors that may affect the fire risk are: The amount of batteries, battery state of charge, possible ignition sources, general fire protection of the storage, and knowledge of battery-related fire. One possible cause of fire during storage and handling of batteries in a warehouse is due to mechanical damage, for example by a falling pallet from truck. Mechanical damage can cause internal short-circuits in the battery cells, which will generate heat, and possibly a fire. Handling by truck is in itself a possible source of ignition as there are examples that a truck has started to burn both during charging and while driving.

At a battery packaging facility we have been in contact with, who receives battery cells directly from a manufacturer, the cells had a charge state of 20 % and were packed according to the transport standard UN 3480. The focus on fire safety and the knowledge of batteries in general was high.

For actors distributing batteries as part of a larger product assortment, the amount of batteries will be substantially smaller, and knowledge of battery-related fire will normally be less. The charging state of batteries in such warehouses is stated to be higher than that of the manufacturer and may be about 50 – 95 %. A high state of charge makes the cells more unstable and based on this we believe that the risk is somewhat higher for such storage, than storage of battery cells with lower charge levels.

At recycling facilities, there is a significantly higher fire risk than storage of new batteries in storage, mainly because cells have been (and are) subject to mechanical stresses in the form of vibrations and shocks, which can lead to more unstable cells and possibly lead to internal short circuits. External short circuits can also occur if the terminals of a battery come into contact through a low-resistance connection. The recycling plants we have been in contact with, have a high focus on fire safety and have taken a number of precautions to prevent a fire to occur, and have put in place measures that can prevent a small fire to develop into a larger fire. The recycling plants seem to have good control over the fire risk of batteries that are checked and sorted, while the fire risk is somewhat higher in the area where the batteries can be unsorted and not currently controlled. Several of the recycling plants experience regular fire outbreaks caused by lithium / lithium-ion batteries, but these cases are normally handled with simple fire extinguishing measures on site.

Based on those we have been in contact with, we believe that the actors with the greatest amount of batteries also have a high focus on fire safety and a great deal of knowledge about battery safety, which together pose an acceptable risk.

The fire risk for actors handling and storing smaller amounts of batteries may be higher, as there is less focus on and knowledge of battery safety.

As the result of this project mainly is based on visiting different actors, there may be other actors with a slightly different focus on fire safety and knowledge about batteries.

The following learning points have been extracted:

General• Have good procedures to reduce fire risk.• Ensure that practices comply with procedures.

Storage of batteries in stock• Keep the cells in as low charge state as possible. When packaging according to UN 3480, this is automatically fulfilled.• Have good dialogue with the local fire department.• Have good truck driving routines to avoid dropping pallets.• Place possible sources of ignition (e.g. truck charger) at a sufficient distance from combustible materials.

Batteries at recycling plants• Limit the amount of batteries in one place.• Store different battery types separated in appropriate storage containers, in a dry location.• Ensure that degassing from batteries may not lead to accumulation of combustible gases.• Keep combustible materials at a safe distance.• Provide a safe zone where unstable batteries can temporarily be stored.• Ensure good training of employees.• Have general order and orderliness.• Access to local fire extinguishing equipment.• Have good dialogue with the local fire department.• Provide good access for the fire service.

Further work is needed to document the fire characteristics of a pallet of non-connected battery cells, in the form of full-scale fire tests to document flammability, fire spread and fire dynamics, and how such a fire can be extinguished.