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What Is Thermal Runaway? Causes, Risks, and Safety for Lithium-Ion Batteries

EcoFlow

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Lithium-ion batteries are in nearly all of our rechargeable devices. Smartphones, laptops, and even electric vehicles rely on them. While lithium-ion batteries keep the world running, they aren’t without their risks.

If these batteries are damaged or exposed to extreme heat, they initiate a chemical reaction known as thermal runaway. This uncontrollable process causes fires and explosions, putting your family in serious danger. Learn what thermal runaway is, what causes it, and how you can prevent it.

Thermal Runaway: A Self-Sustaining Chain Reaction of Heat-Releasing Events

Thermal runaway is a chemical reaction that occurs when a lithium-ion battery overheats. Normally, a lithium-ion battery converts chemical energy into electricity. During this process, it generates some heat, similar to when your laptop warms up due to heavy use. Some heat is okay, but if the battery is damaged or overcharged, it can become too hot, which can cause deadly consequences.

If the battery’s temperature rises too much, the chemical reactions in it accelerate uncontrollably, releasing even more heat. The result is a self-sustaining chain reaction: one cell overheats, igniting neighboring cells within the battery pack. Temperatures can surge past 600°C (1,100°F) in minutes, and since the fire feeds on oxygen, it’s nearly impossible to stop once it starts.

This is why battery fires are so dangerous. The chemical reaction sustains and multiplies heat until it exhausts all available fuel. In fact, fire departments require specialized equipment, such as chemical foam, to extinguish fires fueled by lithium-ion batteries.

Causes and Triggers of Thermal Runaway in Lithium-Ion Batteries

Lithium-ion batteries are surprisingly sensitive. Several factors can trigger a thermal runaway reaction.

Mechanical Damage

Crushing force or punctures can ruin lithium-ion batteries. Excessive vibration and impact can also cause the internal layers of the battery cell to rupture. When the separator (the thin barrier that keeps the positive and negative electrodes apart) breaks, it creates an internal short circuit. This allows current to flow uncontrollably through a low-resistance path, generating intense heat that can ignite nearby materials or cells.

Electrical Abuse

Overcharging a battery can also create thermal runaway. A faulty charger can push a battery beyond its limits. Short circuits caused by manufacturing flaws or faulty wiring can also spike current flow and result in a sharp increase in heat.

Thermal Triggers

If you expose a battery to temperatures above its suggested range (usually 0°C to 60°C), you put it at risk of thermal runaway. Leaving a device in your car or in direct sunlight can trap enough heat in the battery to cause problems in minutes.

Manufacturing Defects and Age

Contaminated lithium and counterfeit materials are more prone to shorting out, even if you use a device according to the manufacturer’s directions. The infamous Samsung Galaxy Note 7 recall is a prime example of manufacturing issues leading to thermal runaway.

Over time, aging batteries also become more unstable. Repeated charge cycles degrade their materials and reduce heat tolerance, making older cells more vulnerable to runaway.

Immediate Consequences of Thermal Runaway

We’re so used to batteries performing well that we often forget their potential dangers. Thermal runaway causes many life-threatening situations that develop in just minutes.

Fire and Explosion

Fire and explosion are the most dangerous and immediate consequences of thermal runaway. As the reaction accelerates, temperatures can exceed hundreds of degrees, igniting the battery’s flammable electrolytes.

In electric vehicles, these fires can spread rapidly through battery packs and are notoriously difficult to extinguish. Even after being cooled or “put out,” cells may reignite hours or days later because residual heat continues to fuel internal reactions.

Gas Emissions

If you manage to escape the blaze or explosion, you also have to worry about toxic gases. During thermal decomposition, batteries release a cocktail of toxic and flammable gases, including carbon monoxide. When ignited, the gases produce intense flames and smoke that can quickly fill enclosed spaces.

Alternative battery types, such as lithium iron phosphate, are less toxic and more environmentally friendly. They might sound the same as lithium-ion, but they’re different. Lithium iron phosphate is more efficient and less likely to experience thermal runaway, making these batteries a safer option for portable power stations like the EcoFlow DELTA 3 Ultra Plus.

Detection, Monitoring, and Safety Measures for Thermal Runaway

Thermal runaway is a significant risk associated with the improper use of lithium-ion batteries. Fortunately, you can take action to prevent thermal runaway and protect your family.

Sensors

High-quality electronics include sensors to measure temperature and voltage in your device. These sensors detect rapid or unusual heat in the system, voltage issues, or off-gassing long before there’s an issue. Thermal runaway can start in seconds, so these sensors can help you detect problems early and shut down the system before a catastrophic failure.

Battery Management Systems

BMS devices keep tabs on the battery’s voltage and temperature. They monitor the health of every cell and automatically adjust performance. In some cases, the BMS will shut off charging if it detects unsafe conditions, like overheating.

Thermal Controls

In some cases, you might need to install a cooling system to keep your electronics operating within a safe temperature range. The most common example is adding a fan to your laptop.

Safe Battery Design

Thermal runaway risks start with faulty product design, so only buy chargers and batteries from trusted manufacturers. Batteries from trusted manufacturers are engineered with thermal insulation, fire barriers, and safety vents to minimize heat buildup.

Smart Use

Proper design can stop some causes of thermal runaway, but you still need to use lithium-ion-powered devices safely. That means:

Following manufacturer guidelines
Keeping batteries cool
Avoiding counterfeit or off-brand chargers and batteries
Ventilating electronics

Alternative Battery Types

Lithium-ion batteries are popular, but they aren’t the only type of battery on the market. For example, lithium iron phosphate (LFP) batteries are a safer option that’s less prone to thermal runaway than lithium-ion.

Frequently Asked Questions

What Are the Dangers of Thermal Runaway?

Thermal runaway is particularly dangerous because it occurs so rapidly. It causes extreme fires, explosions, and toxic gases. Fire departments struggle to contain thermal runaway caused by lithium-ion batteries, making these fires particularly hazardous.

What Is a Thermal Runaway in Simple Terms?

Thermal runaway occurs when a battery overheats, triggering a chain reaction that further increases its temperature. It snowballs in just minutes, quickly creating destructive fires, explosions, and toxic smoke.

Discover EcoFlow’s Safe Portable Power Solutions to Prevent Thermal Runaway Risks

Lithium-ion batteries are everywhere, but they’re so prone to thermal runaway that consumers need to be careful. Buying products from trusted manufacturers and using devices as intended will keep you safe.

Still, batteries using alternative chemistries are less prone to runaway and often have better performance than lithium-ion batteries. Whether you’re powering your home during a blackout or want on-demand power while camping, EcoFlow’s lithium iron phosphate batteries keep you safe. Stay powered up with peace of mind: Check out the EcoFlow DELTA 3 Ultra Plus—one of the safest, most dependable options for portable energy.