Top 5 Reasons Why Lithium-Ion Batteries Catch Fire

The Importance of Battery Safety

Lithium-ion batteries were developed in the 1980s and first commercialized by Sony in 1991 for the company’s handheld video recorder. Today, devices ranging from smartphones to electric cars and even the International Space Station utilize batteries, making enhanced battery safety all the more critical.
In 2008, Tesla unveiled the Roadster, becoming the first car manufacturer to commercialize a battery-powered electric vehicle. By 2025, the global lithium-ion (Li-ion) battery market is projected to reach USD 100.4 billion, with over 50% allocated for the automotive sector.

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Why the Craze for Lithium-Ion?

Lithium-ion batteries are favored for their impressive power output relative to size and weight. A typical lithium-ion battery can store 150 watt-hours of electricity in a 1-kilogram battery. In contrast, a Nickel Metal Hydride (NiMH) battery pack stores only 100 watt-hours per kilogram, and a Lead Acid battery stores just 25 watt-hours per kilogram. It takes 6 kilograms of lead-acid batteries to store the same amount of energy as 1 kilogram of a lithium-ion battery.

Despite their popularity, lithium-ion batteries are particularly sensitive to elevated temperatures and are inherently flammable. These batteries tend to degrade more rapidly under heat. If a lithium-ion battery pack fails, it may burst into flames and cause extensive damage, emphasizing the need for immediate safety measures and guidelines.

Recent incidents highlight the fire risks associated with lithium-ion batteries. For instance, on January 8, 2022, spontaneous combustion of a lithium-ion battery ignited a fire on the COSCO Pacific, a vessel in the Arabian Sea. In April 2022, a 2MW battery at an APS facility in Arizona exploded, injuring four firefighters.

According to Hans-Otto Schjerven, head of the Vestfold Fire Department, rechargeable lithium batteries can ignite fires that are difficult to extinguish, as they emit flames that rapidly spread. As the adoption of electric vehicles increases, such incidents are likely to become more frequent.

Before exploring the reasons why lithium-ion batteries catch fire, it’s vital to understand how they function.

A lithium-ion battery pack comprises lithium-ion cells arranged in modules, which include temperature sensors, voltage taps, and an onboard computer (Battery Management System) to manage the individual cells. Each lithium-ion cell contains a positive electrode (cathode), a negative electrode (anode), and a chemical known as an electrolyte situated between them. While the anode is generally composed of graphite (carbon), various lithium compounds such as Lithium Cobalt Oxide (LCO) and Lithium Nickel Manganese Cobalt (NMC) are frequently employed as cathodes.

When a charging current is applied, lithium ions move from the cathode to the anode through the electrolyte. Electrons also flow but follow a longer path outside the circuit. During discharge, the opposite occurs, with electrons powering the connected application.

Once all the ions return to the cathode, the cell is completely discharged and requires recharging.

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Safety Measures in Lithium-Ion Cells

A. Pressure-Sensitive Vent Holes

Due to internal pressure, lithium-ion batteries require a robust outer metal casing equipped with pressure-sensitive vent holes. If the battery overheats and risk of explosion arises (pressure buildup at 3,000 kPa), these vents will release excess pressure and prevent fire propagation to other cells in the battery pack.

B. The Separator as a Fuse

Most lithium-ion cells feature a separator made from polyolefin, known for its excellent chemical stability, mechanical properties, and affordability. This separator acts as a fuse when excessive heat is generated. At temperatures surpassing 130°C (266°F), the separator melts, halting ion transport and effectively shutting down the cell.

If this safety measure were absent, the heat from a failing cell could initiate a thermal runaway, potentially igniting flames.

C. Positive Temperature Coefficient (PTC)

This mechanism acts as a switch that prevents the battery from overheating, protecting it against current surges.

Like all battery chemistries, lithium-ion cells undergo self-discharge, where they lose stored charge without connecting to electrodes or external circuits due to internal chemical reactions. Self-discharge rates increase with age, usage cycles, and elevated temperatures.

Elevated self-discharge raises temperatures, potentially leading to a Thermal Runaway, also referred to as ‘venting with flame’. Mild shorts typically do not cause thermal runaway since the discharging energy is quite low, generating minimal heat.

However, damage to the cell allowing impurities to enter can create a substantial electrical short. A significant current then flows between the positive and negative plates, causing a dramatic temperature increase and rapid energy release.

Battery packs consist of thousands of closely packed cells. During a thermal runaway, the heat generated by a failing cell may affect neighboring cells, causing them to become thermally unstable. This chain reaction can lead to the destruction of the entire battery pack within seconds.

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Reasons Lithium-Ion Batteries Catch Fire

A. Manufacturing Defects

Flaws in the production process can lead to metallic particles (impurities) infiltrating lithium-ion cells. Battery manufacturers must maintain meticulously controlled cleanrooms during production.

Additionally, separators that are too thin can compromise the cells during operation. Rigorous quality-control testing and validation are essential before cells are sold.

B. Design Flaws

Automakers often aim to design sleek vehicles that maximize range and performance. These goals compel battery pack manufacturers to create compact designs that pack high-capacity cells into smaller spaces, compromising the integrity of otherwise sound batteries.

A flawed design can damage electrodes or separators, leading to short circuits. Moreover, the absence of adequate cooling systems or vents may allow battery temperatures to spike, causing a dangerous flammable electrolyte to heat up.

If left uncontrolled, such conditions can trigger a chain reaction of cell failures and uncontrollable battery heating.

C. Abnormal or Improper Usage

External factors, such as placing a battery too close to heat sources, can result in explosions. Deliberately or accidentally damaging battery packs introduces short circuits, leading to fires. For this reason, unauthorized disassembly of battery packs in electric vehicles voids warranties.

Users should only seek battery inspection and repair from authorized service centers. Overcharging or excessively discharging batteries can also cause damage.

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D. Charger Issues

Using poorly insulated chargers can damage lithium-ion batteries. If a charger shorts or generates heat near the battery, it may lead to failure.

While lithium-ion batteries come with protections against overcharging, using unofficial chargers could harm the battery over time.

E. Low-Quality Components

Besides manufacturing defects, the use of low-quality components significantly contributes to battery failures. Heightened competition has led to lower battery prices, prompting manufacturers to cut corners unnecessarily. Skimping on essential electronics, like the battery management system, heightens the risk of failure.

The battery management system plays a crucial role in ensuring battery safety and performance, protecting packs from operating outside safe limits. Since batteries are high-value components in electric vehicles and energy storage systems, investing in intelligent battery management that can identify cell failures is essential.

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What to Do When a Battery Catches Fire

If a lithium-ion battery begins to overheat, move the device away from flammable materials and disconnect the power supply. In the case of an electric vehicle, evacuate immediately and do not attempt to extinguish lithium battery fires yourself. Your health and safety are the top priority; contact emergency services instead.

For fire containment, a standard ABC or BC dry chemical fire extinguisher is effective as these are classified as Class B fires. A common misconception is that lithium-ion batteries contain actual lithium metal; they do not, so avoid using Class D fire extinguishers.

New methods, such as Aqueous Vermiculite Dispersion (AVD), provide an efficient fire-extinguishing solution by dispersing chemically exfoliated vermiculite in mist form. However, larger lithium-ion fires, such as those in EVs or energy storage systems (ESS), may need to extinguish themselves. While using water containing copper is effective, it can be expensive.

Experts recommend utilizing water even for sizable lithium-ion fires, as they may burn for days. Isolating fires from flammable materials is crucial to preventing their spread.

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Ensuring Battery Safety

Battery pack manufacturers must adopt a strict approach to safety. Lithium-ion batteries can be enhanced by integrating ‘smart’ technologies. By incorporating intelligence into batteries, we can diagnose and predict abnormal usage patterns or performance issues. This proactive approach allows for timely interventions, protecting both the system and battery safety.

For more information on lithium-ion battery safety, reach out to us.

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About Maxwell

Maxwell is an advanced battery management and intelligence platform focused on technologies that extend the life and performance of lithium-ion batteries powering electric vehicles and energy storage systems.

Customers choose ION Energy for its reliability, transparency, commitment to customer success, and innovative business models. OEMs and battery pack manufacturers globally select ION's integrated battery management solutions to continuously enhance battery life and performance.