Why Is Thermal Runaway Protection Important In Manufacturing?

Manufacturing facilities are also at risk – especially if they’re producing the batteries themselves, like the recent disaster in South Korea. If you have any devices or vehicles with Li-ion batteries on your premises, thermal runaway protection is strongly advised. 

One of the biggest dangers is that very few people are yet aware of what thermal runaway actually means. In this article, we’ll address this topic and discuss the issues surrounding Li-ion battery fires. Armed with this information, you’ll be able to use your batteries in greater confidence that your manufacturing operations are powered responsibly and safely.

What Is Thermal Runaway?

Fire usually depends on fuel to continue burning. If no fuel supply is available, it will eventually burn itself out. But in cases like forest fires and extreme chemical blazes, that doesn’t happen. With an inexhaustible supply of fuel, the fire keeps getting hotter and hotter, releasing radiant energy in the form of light and thermal energy in the form of heat. 

This thermal energy drives the temperature up higher, releasing yet more energy. This is thermal runaway: a self-perpetuating cycle of increased temperature releasing more energy, creating further temperature increases. This cycle will continue until the original fire develops into something incredibly hot and extremely dangerous.

These aren’t just any ordinary kind of fires. They spread faster, burn hotter and are immensely difficult to extinguish. The temperatures involved in some cases are so high that a blaze may actually re-ignite, even after having been put out. This is considered a direct result of thermal runaway and means fighting Li-ion battery fires by means of oxygen deprivation is less likely to be effective. 

Causes Of Thermal Runaway

Thermal runaway is trending in many branches of science, from electrical and chemical engineering to theories on global warming. Of most interest to manufacturers is its relevance to electric vehicles and Li-ion batteries, plus electrical overloads and situations where an exothermic chemical reaction may develop. This includes chemical plants, oil refineries and concrete-curing facilities. 

When we understand how thermal runaway happens, we can implement strategies for avoiding it. In this way, you’ll be helping to ensure the safety of your employees and your business operations. The most common reasons that thermal runaway occurs include:

• Rapid battery charging drawing down excessive current

• Over-charging a battery past its safe voltage levels

• Over-discharging a battery multiple times and then charging it

• Physical battery damage such as puncturing or crushing

• Manufacturing defects

• Short circuits, whether internal or external 

• Excess moisture

• Extreme temperature environments

Thermal runaway is a highly dangerous phenomenon, occurring when a system or piece of equipment develops a self-sustaining temperature rise. The self-sustaining temperature increases may eventually cause batteries to release toxic flammable gases, which then catch fire or explode. 

As battery cells continue to decompose and vent flammable gases, the fire will spread – far more rapidly than any other kind of fire. Not only is this type of fire harder to extinguish, but larger batteries are capable of reignition hours or even days after the original event. 

Thermal Runaway Temperatures In Lithium-ion Fires

Li-ion batteries are judged to be fairly safe operating at temperatures up to 140° F (60° C). At temperatures higher than this, the battery is likely to become unstable, which will probably end in thermal runaway. In this event, Li-ion fires generally ignite at temperatures around 932° F (500° C) and are capable of reaching as high as 2000° F (around 1100° C). It’s the reignition factor, though, that causes the greatest concern. This happens because the battery’s lithium salts are self-oxidising, so you can't put them out like a traditional fire with oxygen starvation. 

Why Is Thermal Runaway Becoming So Common?

The main reason we’re seeing more Li-ion fires is the more widespread adoption of the technology itself. Li-ion batteries are becoming more prevalent in various industries, processes and circumstances, but the safety risks have not yet been adequately evaluated. Handheld devices, remote technology and electric vehicles are being integrated into many concerns, including such large-scale operations as the defence sector’s ‘battlefield electrification’ project, often with insufficient consideration of the potential safety risks.

How To Implement Thermal Runaway Protection In Manufacturing

It’s still early days for this technology, so no official standards for the fire safety performance of Li-ion batteries have yet been formulated. General requirements and tests are included in IEC 62133, governing the performance and safety of Li-ion batteries sealed into portable electronic devices, but no guidance is available for larger units such as those used in vehicles and energy storage facilities.

What you can do is protect your facilities as far as possible from thermal runaway by using a few sensible precautions:

• Use only high-quality Li-ion batteries that have safety features built in, such as protection against overcharge and over-discharge.

• Handle Li-ion batteries with caution and store them properly to ensure safer and more efficient operations

• Don’t expose batteries to extreme temperatures

• Never leave charging batteries unattended, as they could overcharge or overheat

Are Li-ion Batteries Safe For Industrial Use?

If you do experience a thermal runaway fire, you’ll require specialist equipment to put it out and preferably professional assistance. Water and oxygen deprivation aren’t very effective against self-sustaining thermal runaways, but specialist battery storage solutions might come with dedicated suppression systems. Be very careful if you’re investing in this sort of technology.

Li-ion batteries are usually considered safe in certain circumstances, but so far these have mainly been associated with portable devices. The recent publicity around Li-ion fires demonstrates that better education and training is required, especially in new environments like manufacturing. This can be included in general programmes of machine safety training, with special highlights on mitigating the risks of thermal runaway.