What can cause a lithium-ion battery explosion?

Rob Sherman
24th June 2024

Lithium-ion battery explosions are extremely rare, but when they do happen, they are very dangerous because lithium-ion fires release toxic gases and are difficult to extinguish.

Over the years there have been product recalls for devices including hoverboards, smartphones, e-bikes and e-scooters. In recent months there has been a product recall for Vanon lithium-ion battery packs and for  1.2 million rechargeable lights following safety concerns and reports of fires.

Here we discuss how lithium-ion batteries work, why they are used, what can cause a lithium-ion battery explosion and what you can do to minimise the risk to lives and property.

How do lithium-ion batteries work?

Lithium-ion batteries make energy through the movement of lithium ions between two electrodes: a positive cathode and a negative anode. A gel-like electrolyte facilitates the movement of these ions, while a separator ensures the electrodes do not touch but allows ions to pass through.

During the charging process, an external power source applies a voltage across the battery, causing lithium ions to move from the cathode to the anode through the electrolyte, and electrons to flow from the cathode to the anode via the external circuit.

When discharging, the ions move back from the anode to the cathode, and electrons flow through the external circuit to power the device.

What are the advantages of lithium-ion batteries?

• Lightweight. As they have a high energy density, they can store a large amount of energy in a small, lightweight package.
• Versatile. They can be used in a wide range of applications, from small consumer electronics to large-scale energy storage systems.
• Environmental impact. When used in electric vehicles and renewable energy storage, li-ion batteries have lower greenhouse gas emissions than fossil fuel-based technologies.
• Long lifecycle. They can be recharged many times before their capacity significantly degrades.
• Efficient. Compared to other battery types, lithium-ion batteries have a low self-discharge rate. This means they retain their charge longer when not in use.
• Fast charging. They can be charged more quickly than many other types of batteries.
• No memory degradation. Lithium-ion batteries do not lose their maximum energy capacity if they are repeatedly recharged.

What are the dangers of lithium batteries?

Lithium-ion batteries have a high energy density, storing significant energy in a compact space, making fires intense and hard to control.

Overheating in one cell can trigger a chain reaction, leading to a rapid and uncontrollable temperature rise (called ‘thermal runaway’), potentially causing explosions or fires. The electrolyte, a flammable liquid, can ignite if the battery is damaged or short-circuited.

Burning lithium-ion batteries release toxic gases like hydrogen fluoride and carbon monoxide, complicating firefighting. Even after appearing extinguished, residual energy can cause the battery to reignite.

What is the biggest cause of a lithium-ion battery exploding?

These are the factors that may lead to a lithium-ion battery exploding:

1. Overcharging. Charging a lithium-ion battery beyond its capacity can cause excessive heat buildup, leading to thermal runaway. This can cause the battery to catch fire or explode.
2. Overheating. High temperatures can destabilise the chemical structure of the battery, potentially leading to a thermal runaway. This can be caused by environmental factors, such as leaving the battery in a hot car, or by internal factors, such as a malfunctioning device.
3. Short circuit. If the battery terminals come into direct contact, it can cause a short circuit, leading to rapid discharge and heat buildup, which may result in an explosion.
4. Physical damage. Puncturing, crushing, or otherwise damaging a lithium-ion battery can breach its internal structure, causing a short circuit or other failure modes that can lead to an explosion.
5. Manufacturing defects. Flaws in the manufacturing process, such as impurities in the materials, poor assembly, or defective components, can create conditions where the battery becomes unstable and prone to failure.
6. Improper charging. Using a charger that is not compatible with the battery or one that delivers the wrong voltage can cause overcharging and overheating which might lead to an explosion.
7. Aging and wear. Over time, lithium-ion batteries degrade, and their internal components can become less stable. This degradation can increase the risk of a failure that might lead to an explosion.
8. Electrolyte leakage. The electrolyte inside lithium-ion batteries is flammable. If it leaks due to damage or manufacturing defects, it can ignite, especially if it comes into contact with a spark or high heat source.
9. Poor ventilation. Lithium-ion batteries generate heat during charging and discharging. If they are enclosed in a space with poor ventilation, the accumulated heat can lead to thermal runaway.

How do you know if a lithium-ion battery is failing?

If you notice any signs that a lithium-ion battery is failing, it is advisable to replace the battery or consult a professional for a thorough check. Ignoring these symptoms can lead to fires.

How can you prevent a lithium-ion battery explosion?

As well as checking for signs that a lithium-ion battery is failing (see above), you can also minimise safety risks by:

• Purchasing devices from reputable suppliers.
• Not overcharging batteries.
• Only using the manufacturer’s recommended charger for a device.
• Checking chargers and devices for signs of damage before use.
• Not leaving devices in direct sunlight.
• Disposing of batteries and devices properly and not in the general waste. Lithium-ion batteries must be taken to a local recycling centre.

For more about how to prevent lithium-ion battery explosions and fires and what to do in an emergency please read, How common are lithium-ion battery fires?

Lithium-ion battery safety training

Our lithium-ion battery safety training ensures participants are aware of the dangers of lithium-ion batteries and what simple steps they can take to prevent lithium-ion battery explosions and fires.

Although lithium-ion battery fires are rare, when they do occur, they pose a significant risk to life and property.

Find out more about lithium-ion battery safety training or contact our friendly team for further information.

Rob Sherman

Director of Fire Safety

Rob is the Director of Fire Safety at Praxis42. He joined in 2014 after serving with the London Fire Brigade for 32 years, so fire safety is basically in his DNA. Rob is passionate for saving lives and ensuring quality standards. At Praxis42, he is responsible for delivering customer fire safety support through a framework of training, information and third-party accreditation.