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What causes lithium-ion battery fires?

While lithium-ion batteries offer convenience, they come with risks. SafeQuip, a distributor of fire safety equipment, explores the construction of lithium-ion batteries, the risk of thermal runaway, and the associated hazards of these power sources.

Understanding lithium-ion battery construction

At their core, lithium-ion batteries consist of three essential components:

1. Anode: This is the negative electrode, typically made of a carbon-based material that stores lithium-ions when the battery is charged.

2. Cathode: The positive electrode, often composed of lithium cobalt oxide or other lithium-based compounds, is responsible for receiving and releasing lithium-ions during charging and discharging.

3. Electrolyte: This is like the battery's bloodstream. It is a liquid or gel that helps lithium ions move around between the cathode and anode. It is important to note that the liquid or gel is flammable.

These three elements are sandwiched together and housed within a protective casing. The casing serves as a barrier to contain the potentially volatile materials inside the battery.

The phenomenon of thermal runaway

Thermal runaway in lithium-ion batteries is a dangerous situation where the battery gets extremely hot, leading to the rapid release of heat and gases, which can result in fires or explosions. Several factors can trigger thermal runaway, including:

• Overcharging:Charging a lithium-ion battery beyond its recommended voltage limits can cause the electrolyte to break down, leading to overheating.

• Physical damage: Punctures, crushing, or mechanical stress can compromise the battery's structure, allowing internal components to come into contact and generate heat.

• High temperatures: Exposure to excessive heat, such as leaving a device in a hot car, can accelerate the onset of thermal runaway.

• Manufacturing defects: Faulty manufacturing processes or substandard materials can weaken the battery's internal components, increasing the risk of thermal runaway.

Potential hazards

Potential hazards associated with lithium-ion batteries include:

1. Fire: When a lithium-ion battery undergoes thermal runaway, it can generate enough heat to ignite the internal materials or surrounding objects. This can lead to a fire, posing a significant safety risk.

2. Explosion: In extreme cases, the buildup of pressure from the gases produced during thermal runaway can rupture the battery casing, resulting in an explosion. While such incidents are rare, they can cause severe injuries or property damage.

3. Toxic gas emission: Lithium-ion batteries may emit toxic gases, such as hydrogen fluoride and phosphorus pentafluoride when they overheat or explode. Inhalation of these gases can be harmful to human health.

Mitigating the Risks

Some practical steps to help you stay safe include:

• Use genuine batteries: Always use genuine, manufacturer-recommended batteries and chargers for your devices. Counterfeit or substandard products are more likely to pose risks.

• Avoid extreme temperatures: Keep your devices and batteries away from extreme temperatures, both hot and cold. Avoid leaving them in direct sunlight or inside a hot vehicle.

• Inspect for damage: Regularly inspect your devices and batteries for any signs of physical damage, such as swelling, punctures, or leaks. If you notice any issues, replace the battery or device as needed.

• Charge safely: Charge your devices on non-flammable surfaces, away from combustible materials. Do not leave them unattended while charging, especially overnight.

• Store properly: If you need to store lithium-ion batteries for an extended period, keep them in a cool, dry place with a partial charge (around 50%). Avoid storing them fully charged or fully depleted.

• Dispose of old batteries: When it is time to replace a lithium-ion battery, recycle it properly.

• Invest in a fit-for-purpose fire extinguishing solutions: A lithium fire is very difficult to extinguish without the appropriate equipment designed for these emergencies. (Refer to the Products & Solutions section for lithium-specific suppression solutions.)

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