Lithium-Ion Battery Fires

With an increasing number of lithium-ion (or li-ion) batteries in circulation, it's important to understand what they are, how to safely store and use them and the dangers they can pose. This guide takes a look at where lithium-ion batteries are found and how to avoid fires that start inside the battery cells. Read more about the early warning signs of a defective battery, and the solutions available to businesses and organisations to prevent and contain a lithium-ion battery fire.

What is a lithium-ion battery?

Lithium-ion batteries is a broad term for various types of rechargeable battery. The exact chemical mix in the battery can vary such as Lithium-ion Phosphate (LiFePo4) and Lithium-ion Manganese Oxide. It is key to remember that lithium-ion batteries should NOT be confused with non-rechargeable lithium batteries, which can be found in products such as 10-year battery smoke alarms, or typical coin-cell batteries. Typically, lithium-ion batteries have a high energy density, which means that they can store a lot of electricity whilst staying small and lightweight.

What products use lithium-ion batteries?

Lithium-ion batteries are rechargeable and are very common within our homes, workplaces, and social lives. There is an exhaustive list of products that utilise lithium-ion batteries, and these batteries can take the form of standard household batteries including AAA to 9V, as well as batteries for e-scooters and e-bikes.

Here is a list of common items that use lithium-ion batteries;

• Mobile phones
• Tablets
• Laptops
• Rechargeable vapes
• Bluetooth headsets
• Cameras
• Electric toothbrushes
• E-bikes
• E-scooters
• Rechargeable power tools
• Hoverboards
• Electric Vehicles (EVs)

This is by no means every product that utilises this type of battery, however it is key to note that if the product needs charging it is likely to contain a lithium-ion battery.

What is a lithium-ion fire?

Lithium-ion fires are fires that have started inside lithium-ion batteries. These often occur when a lithium-ion battery generates heat from charging when the cells are slightly malformed. Malformation of a battery’s cells can be caused by many factors such as cell damage, overcharging, incorrect storage, or being depleted until they are completely flat. The damage to the battery may not be immediately obvious as it may not have any physical damage to the outside casing.

Once the battery’s cells have started to generate heat and become overheated, they can enter a state of thermal runaway, where the fire quickly spreads and affects the other cells within the battery. It only takes one defective cell to initiate thermal runaway. This can happen so quickly that toxic gases rapidly develop within the casing, causing it to explode. This enables the fire to spread externally, especially if another fuel source, such as paper or clothing, is nearby.

What are the warning signs for the start of a lithium-ion fire?

With proper care, the chance of a lithium-ion battery fire starting is greatly reduced. However, there are some key warning signs to look out for, to prevent a fire from starting or getting out of control. If any of these signs are noticed, immediate action should be taken to reduce the risk of fire.

• Heat – Although it is normal for a lithium-ion battery to produce some heat while in use and on charge, if the battery becomes extremely hot to touch there is a high chance the cell within has become defective and may start a fire.
• Bulging – A common sign of a failing lithium-ion battery. If the battery looks deformed, is bulging, shows any sign of a lump, or appears to be leaking, the battery should not be used and should be disposed of responsibly.
• Noise – Due to the release of gases, it has been reported that failing lithium-ion batteries make hissing or cracking sounds.
• Smell – When a lithium-ion battery starts to fail, it may begin to release toxic gases which will give off an unusual smell.
• Performance – A decrease in performance after a charge, or not even achieving a full charge can be a sign that a battery has begun failing.
• Smoke – The sign of smoke, is your last and final warning sign. Upon seeing smoke from the battery or device, the fire has already begun and immediate action should be taken.

Why are lithium-ion battery fires becoming such an issue in the UK?

Across the UK, homes and businesses now rely on so many devices powered by lithium-ion batteries. The prevalence of these devices and the lack of knowledge by end users as to the dangers has led to increasing numbers of fires from lithium-ion batteries. A guidance document published by the Department for Transport in 2024 stated there were 338 fires from e-bikes and scooters in the UK. And, a European study by CORDIS suggests that by 2025, 78 million lithium-ion batteries will be discarded daily worldwide. These statistics illustrate the extent of the problem, and with our appetite for rechargeable products, the problem is likely to become more prevalent.

The unregulated sale of lithium-ion batteries, chargers and products containing these batteries in the UK is contributing to the issue. Charity ‘Electrical Safety First’ are currently championing proposed legislation that covers the sale of some products containing lithium-ion batteries, their safety and disposal.

The danger of li-ion batteries in the home

Generally, within the home, lithium-ion batteries are charged overnight and often situated in high-risk locations such as on the bed or even in the hallway which forms part of the primary escape route. Doing so, can lead to the battery overheating and a fire starting, potentially blocking their emergency route out of the home or flat.

It is common to see individuals retrospectively upgrading their bikes with e-bike conversion kits and using unbranded chargers, which are often cheaper and poorly manufactured in comparison to that of a reputable seller. These can often be installed incorrectly, become defective and can potentially be the start of a fire. These have been identified as particularly dangerous by the Electrical Safety First campaign in their “Battery Breakdown” report.

Lithium-ion batteries in businesses and organisations

This type of battery is now prevalent in businesses and organisations with power tools, electric vehicles, computing equipment and handheld devices all being powered by li-ion batteries. All of these require charging on a regular basis, and generally within business hours. Many companies have made the change to rechargeable options as it is seen as a more environmentally friendly approach. With the rise of electric vehicles on roads in the UK, it is common to see electric vehicle chargers situated on the external walls of business premises. These chargers pull a large amount of power and like all chargers generate some heat whilst in use. It is recommended that only the correct chargers should be used for the vehicle and should be at least 2m clear of combustible and flammable materials.

In some professions, especially in trades which are maintenance based, it is common for tools to be accidently dropped. Using equipment with li-ion batteries that may be damaged means that even when they are not on charge, it can go into thermal runaway when in use. This is extremely dangerous as the device may catch fire whilst in an individual’s hand and near combustible materials. It is strongly recommended that if the device has been dropped, even without any visible physical damage, that the device should be responsibly disposed of and replaced.

How can I safely charge and store my lithium-ion batteries?

As well as looking out for warning signs of a lithium-ion battery fire, it is key to ensure that batteries are charged and stored correctly. Safely storing and charging batteries means that even if a fire does begin the damage can be limited and contained.

The safe storage of lithium-ion batteries

• Never in direct sunlight
• Do not expose to extremes of temperature, both high and low
• Do not store close to other items, such as paper or fabric
• Do not allow batteries to get wet or to be exposed to moisture

Charging of lithium-ion batteries

• Always follow the manufacturer’s instructions
• Use the correct charger
• Unplug the charger once it has completed
• Buy replacement batteries and chargers from a reputable seller, ideally the manufacturer
• Charge on a hard flat surface to allow for the heat generated to dissipate
• Never charge when you are asleep or the battery is unattended

It is important to remember that a lot of premises, especially residential, only have one main escape route. So, it is crucial that the charging and storing of these batteries is not done along this route.

Can you put out a lithium-ion battery fire?

Lithium-ion batteries can ignite spontaneously, burning at incredibly high temperatures and are very unpredictable. Being almost impossible to extinguish, the usual approach by the fire service is to cool the battery down as much as possible using a lot of water, and then to remove the battery to an area where it can be left to burn out. The danger of reignition after the fire has been initially cooled is an issue up to 30 days. Therefore, this causes problems for the transportation and storage of the object containing the battery or the battery itself.

Tackling a lithium-ion battery fire is not advised unless the person is wearing full personal protective equipment (PPE), including breathing equipment to protect themselves from the toxic gases, and are trained to deal with that type of fire. Even then, the decision may be taken that the fire cannot be approached due to its ferocity and unpredictability.

There are currently no standards surrounding the installation and use of lithium-ion fire solutions. However, many organisations are becoming aware of the risk and fire risk assessors should take into consideration an lithium-ion battery risks.

Lithium-ion fire extinguishers

Lithium-ion fire extinguishers use a new and revolutionary extinguishing agent, Aqueous Vermiculite Dispersion (AVD). These have specifically been designed for use on lithium-ion batteries. Vermiculate is a naturally occurring mineral, and has excellent thermal insulation properties and is non-flammable.

When AVD is applied to a lithium-ion fire, it is dispersed in the form of a mist which allows for the water to suppress the flames, cooling down the fuel source. When the water cools and evaporates, it creates an insulating film to prevent re-ignition.

Although lithium-ion fire extinguishers have some benefits, great care should be taken when tackling li-ion fires due to their ferocity and unpredictability. The best advice is always to leave the premises as quickly as possible and to call the fire brigade. Li-ion fire extinguishers would act to cool and suppress the fire, and would prevent reignition if they were successful in extinguishing the fire. With lithium-ion batteries having robust casing, and in many cases having an IP rating to stop water ingress, penetrating the casing to reach the cells where the source of the fire has occurred is challenging.

Lithium-ion battery containment solutions

Due to the volatile nature of a lithium-ion fire, the general advice is to get out of the premises and call the local fire service. If the fire is outside, maybe an electric vehicle, the advice is to stay at a safe distance and again, call the local fire service.

Some companies have designed containment and suppression solutions to minimise the damage to property, including battery safes and charging cabinets. Tackling a li-ion battery fire once it has started is very difficult and dangerous. Putting in place measures such as safe charging and storage facilities at your premises allows for containment and prevention before the fire is able to escalate. Effective containment of lithium-ion batteries during charging is strongly recommended as a preventative measure.

The li-ion battery safes and storage cabinets work in such a way that if a fire was to start inside, it would be contained without the chance or opportunity to spread throughout a property. Some of these types of storage solutions have integrated smoke detection so that the doors are not opened whilst a battery is burning.

Fires involving electric or hybrid vehicles

Electric vehicle fires are rare, but when they do occur the results can be disastrous. Electric vehicles draw an increased amount of attention as they are incredibly complex with their technology and are extremely difficult to extinguish. As well as being difficult to extinguish, there is also still the chance that the lithium-ion battery could reignite hours or even days after it has been initially cooled. This poses an increased danger when electric vehicles that have been cooled in order to extinguish a fire, have to be transported and stored.

The current preferred approach actioned by many Fire and Rescue Services is to tackle the electric vehicle fire with an immense quantity of water to cool the battery, although this does not prevent re-ignition. In addition, a car fire blanket can be used to suppress the flames and contain the fire. During this firefighting task, firefighters protect themselves from the release of toxic gases by wearing full PPE including appropriate breathing equipment.

An EV car fire blanket works in a very similar way to a kitchen fire blanket, where it is placed over the top of the fire to cut off the oxygen supply from the atmosphere to the fire. As car fire blankets are quite large, it is key to remember it requires two or more people to deploy and generally by those who are trained to use such equipment, for example the fire service.  With this in mind, the key advice for any vehicle fire, especially for electric vehicles (EVs) is to get to safety and call for the emergency services. Businesses and organisations with electric vehicles including foklifts or EV chargers at their site may wish to consider keeping an electric vehicle fire blanket at their premises. The blankets can be used as a preventative measure before fire breaks out if an early warning sign is detected, or if the vehicle has been involved in an accident. Keeping a car fire blanket on the premises also means the fire service have access to it when they attend the scene - it is an additional tool to suppress the vehicle if required. An EV blanket could also be used on neighbouring vehicles or property to stop the spread of fire from the affected vehicle.

Safe disposal of lithium-ion batteries

It is crucial that lithium-ion batteries are disposed of responsibly, especially when they are damaged, to avoid any environmental or safety impacts. Due to the potential safety risk, it is strongly recommended that these batteries are NOT disposed of in your general rubbish. Discarded batteries in household or business waste could easily be damaged, crushed or exposed to temperature changes and moisture, increasing their risk of fire. With other flammable materials in the waste, the potential for fires to spread is great. Lithium-ion batteries which have been discarded in domestic and business waste were responsible for 201 fires every year according to a report by Eunomia Research.

Local recycling centres often accept many different types of electrical equipment, including lithium-ion batteries. However, it is advisable to check with your local recycling centre to ensure that they are able to accept them. Other drop off locations, setup by local governments and independent recycling centres will accept lithium-ion batteries for recycling.

If the batteries are required to be stored for a period of time before they are disposed of, ensure that they are stored in a cool, dry location out of direct sunlight and away from other flammable items. A lithium-ion battery that does not function could still go into thermal runaway and catch fire.