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What causes lithium-ion battery fires? Why are they so intense? And how should they be fought? An expert explains

Picture this: you’re cruising down the Great Ocean Road in your brand new electric vehicle (EV), the ocean to your left and the wind in your hair. But what if I told you this idyllic drive could turn into a nightmare, with the faint smell of something burning?

This month we have had at least two large lithium-ion battery fires in Australia – one in the Sydney airport car park and another one more recently at the Bouldercombe battery storage site in Queensland.

When a lithium-ion battery fire breaks out, the damage can be extensive. These fires are not only intense, they are also long-lasting and potentially toxic.


Read more: Electric vehicle fires are very rare. The risk for petrol and diesel vehicles is at least 20 times higher


What causes these fires?

Most electric vehicles humming along Australian roads are packed with lithium-ion batteries. They’re the same powerhouses that fuel our smartphones and laptops – celebrated for their ability to store heaps of energy in a small space.

The reality is lithium-ion batteries in electric vehicles are very safe. In fact, from 2010 to June 2023, only four electric vehicle battery fires had been recorded in Australia. A recent paper forecasts a possible total of around 900 EV fires between 2023 and 2050. This is, for all intents and purposes, a small amount.

Nonetheless, when EV batteries do overheat, they’re susceptible to something called “thermal runaway”. This chemical reaction can be triggered from faults in the battery – whether that’s an internal failure (such as an internal short circuit) or some kind of external damage. In extreme cases, it causes the battery to catch fire or explode.

The onset and intensification of lithium-ion battery fires can be traced to multiple causes, including user behaviour such as improper charging or physical damage.

Then there are even larger batteries, such as Megapacks, which are what recently caught fire at Bouldercombe. Megapacks are large lithium-based batteries, designed by Tesla. They are intended to function as energy storage and to help “stabilise the grid and prevent outages”.

The Megapack that caught fire on Tuesday is one of 40 lithium-ion Megapack 2.0 units on-site. A Megapack fire is daunting for obvious reasons. These have a capacity of 3 megawatt hours, which equals 3,000 kilowatts of electricity generated per hour.

It’s no surprise the Bouldercombe fire may be burning for several days.

What to do when a fire has started?

If a fire bursts out in an EV or battery storage facility, the first instinct may be to grab the nearest hose. However, getting too close to the fire could spell disaster as you may be injured by jet-like flames or projectiles.

In the case of up-and-coming solid-state batteries with a lithium metal anode (instead of the more common graphite anode), these have a rather unwelcome talent for chemical reactions when they come into contact with water.

Instead of snuffing out the flames, water could actually fuel the fire and cause it to intensify. This is because the water’s reaction with the lithium can produce flammable hydrogen gas – adding more of a hazard to an already perilous situation.

While firefighters have used water on lithium-battery fires in the past (as it can help with cooling the battery itself), they have at times needed up to 40 times as much as a normal car fire requires.

It may often be safer to just let a lithium battery fire burn, as Tesla recommends in its Model 3 response guide:

Battery fires can take up to 24 hours to extinguish. Consider allowing the battery to burn while protecting exposures.

This could explain why Tesla advised authorities in Bouldercombe to not put out the blaze.

Water also conducts electricity, which means spraying it on a battery fire could lead to electrical shocks or short-circuits if the battery is not electrically isolated.

Globally, numerous solutions have been proposed for extinguishing lithium-ion battery fires. However, as of now, neither Australian standards, nor any other internationally-recognised guidelines adequately address fire extinguishing requirements for this purpose.

Importantly, the appropriate fire extinguishing method will vary depending on the type of lithium battery in question (such as lithium-ion, all-solid-state lithium-ion or lithium polymer).

For standard lithium-ion battery fires, the sprinkling of fine water mist may be used to suppress the fire. On the other hand, experts recommend using specially-designed Class D fire extinguishers for solid-state lithium-metal battery fires – or dry chemical fire extinguishers that are appropriate for electrical fires.

These contain substances, such as sodium chloride powder or pressurised argon, that can combat the challenges posed by solid-state batteries. Sodium chloride, commonly known as table salt, melts to form an oxygen-excluding crust over the fire. Similarly, argon is an inert and non-flammable gas which can help put out fires by suffocating oxygen.

That brings us to the aftermath of the fire – and another often-overlooked hazard: toxic fumes. When lithium-ion batteries catch fire in a car or at a storage site, they don’t just release smoke; they emit a cocktail of dangerous gases such as carbon monoxide, hydrogen fluoride and hydrogen chloride.

These fumes can be hazardous to your health, especially when inhaled in significant quantities. This is why these battery fires are a particular concern in confined spaces such as a garage, where noxious gases can accumulate quickly.

What to do if your car catches fire

Although EV fires are very rare, if you do own an EV (or plan to in the future), there are a few steps you can take to tip the scale in your favour.

First, get to know your EV inside and out. Familiarise yourself with its safety features. Does it have a functioning thermal management system to help keep the battery cool? What about sensors that could alert you to a problem before it turns into a crisis?

Secondly, be smart about how you charge your EV. Avoid overcharging your battery as this can increase the risk of it lighting up.

If, despite your best efforts, you find yourself head-to-head with a blaze, your first course of action should be to call emergency services for professional help.


Correction: Since this article was published it has been updated in several places to better distinguish where the author is referring to solid-state (lithium anode) or lithium-ion batteries. A reference to fire risk from fast-charging batteries has also been removed.

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