From e-scooters to smartphones to large-scale storage grids, lithium-ion batteries are everywhere. But should we better manage these risks?
On 30 July 2021, as it was undergoing testing shortly before it was set to be brought online, Victoria’s Big Battery caught fire.
Located in Moorabool, near Geelong, the 300 MW/450 MWh battery grid is the largest in Australia, and one of the largest in the world.
At the time, it was using Tesla Megapacks that featured lithium-ion batteries with nickel manganese cobalt (NMC) chemistry.
Two of the 212 megapacks were damaged in the blaze, which burned for more than three days and made headlines around the world.
The phenomenon that causes lithium-ion batteries to catch fire like this is known as “thermal runaway”.
Associate Professor Robert Kerr of the Institute for Frontier Materials at Deakin University said this is caused when a battery cell starts to rapidly overheat.
“When you get that heating, at some point the cathode materials will start to release or liberate oxygen; it’s an exothermic reaction itself that starts to generate more heat,” he explained.
“It’s self-heating, self-perpetuating, and once it reaches that point, you can’t stop it – you get runaway.”
A subsequent investigation by Energy Safety Victoria found that the likely cause of the Big Battery fire was a leak within the megapack cooling system, which caused a short circuit and triggered the runaway event.
Thankfully, though, nobody was injured in the fire, and the megapacks are considered to have “failed safely”.
Lithium-ion batteries – like those often used in megapacks, and all manner of other devices – are a critical part of Australia’s efforts to decarbonise and increase renewable energy storage capacity.
But, as the Victorian Big Battery fire shows, they do pose safety risks, and Australia currently has little regulation governing their usage, storage, and disposal.
In December, the Australian Competition and Consumer Commission (ACCC) released a lithium-ion batteries issues paper, citing the fact there is “no regulatory framework or mandatory safety standard which squarely addresses the risks with Li-ion batteries in Australia”.
Associate Professor Alexey Glushenkov, Research Lead in Battery Materials at the Australian National University’s Battery Storage and Grid Integration Program, said, despite the headlines, lithium-ion batteries are generally safe.
“Overall, lithium-ion battery cells are very robust and very reliable,” he said. “Having said that, there is a low probability event that some of them might go wrong, and sometimes they do – so we see accidents happening from time to time.”
Glushenkov said the lithium-ion proliferation comes down to the fact the batteries can pack a huge amount of energy into a small space.
“They offer the best practical energy density – also called specific energy – which means the amount of energy that you can pack into a given volume or given mass,” he said. “But they do have some flammable components, like carbon electrode materials: for example, organic electrolyte.
“And they are sensitive to abuse, so to speak – you shouldn’t overcharge them, shouldn’t overheat them; sometimes there could be also gas evolution inside … and there is a possibility of growing lithium dendrites inside of the cell.
“All these sort of abuse types and mechanisms may lead eventually to fire in lithium-ion batteries.”
Glushenkov said most reputable companies ensure high safety standards and testing, but this is not the case for all battery manufacturers.
He added that, while “lithium-ion” is often used as a catch-all term, different lithium-ion battery chemistries have different risk profiles.
The commonly used NMC is a powerhouse when it comes to energy density but poses a greater risk of thermal runaway.
Another common chemistry, lithium iron phosphate (LFP) trades off on density but reduces combustion risk.
According to a recent report commissioned by the Australian Energy Council into large-scale battery hazards, Tesla has since reconfigured the megapacks in the Victorian Big Battery after the fire at Moorabool and updated them to LFP chemistry.
Rise of the battery
Lithium-ion batteries aren’t only used in grid-scale storage; They’re in devices all around us.
The recent rise in popularity of e-mobility vehicles like e-scooters and e-bikes has also brought with it increased reports of battery fires.
As reported by the ABC, the New South Wales fire department logged more than 450 fires related to e-scooters and e-bikes in a recent 18-month period.
Dr Matthew Priestley, Lead Technology Translator at the Digital Grid Futures Institute at University of New South Wales said that while these cases are concerning, proper usage can minimise the risk of fire in these devices.
“At the moment, the public is only thinking of battery safety in regard to e-bikes, because that’s what they’ve been told in the media is potentially dangerous,” he said.
“What we’re finding in the e-bike sector though is if you use a charger that’s actually been designed for the bike, follow the manufacturer instructions on safe usage, and you’re using a reputable e-bike – not one that you built yourself – the risk of battery failure is very low.”
What’s much more concerning, Priestley said, are aspects such as the current storage and disposal practices of high-energy lithium-ion batteries in Australia.
Priestley said one concerning area his team is investigating is how high-energy batteries are stored in Australia.
“When we bring these batteries in from overseas where they’re manufactured, we have to put them somewhere; at the moment, some companies are storing them in warehouses – without properly considering the safety implications,” he said.
“These warehouses are often rated to carry dangerous goods, but they’re not really rated, in my view, to take the total level of energy lithium-ion batteries that are there – particularly when some of these batteries require storage at 30 to 50 per cent state of charge.
“The scariest thing is sometimes these warehouses are in suburbia; you wouldn’t even know if there’s one down the road from you if you live in an industrial area.”
Priestley said he’s inspected these facilities and witnessed some worrying practices.
“I was in one a couple of days ago and it had thousands of kilowatt hours of energy storage all sitting right next to each other,” he said.
If a forklift accidentally pierced one of those, disaster could result.
“We asked them what they would do in that situation – if one of these batteries was to light up,” Priestley said.
“Their answer was: we’d move it outside – but there’s no way that you can safely move one of these outside once the battery moves into thermal runaway.”
Priestley pointed out these practices are currently perfectly legal due to a lack of regulation.
“None of the stuff I’ve seen is technically illegal – but it’s unsafe,” he said.
He said it’s important to note that most reputable high energy lithium-ion battery companies are taking proper safety precautions when storing their products.
“However, some cheaper brand competitors appear to be hoping nothing goes wrong and not designing any procedures for if something does go wrong.”
Another area of concern is the disposal of spent batteries.
Priestley’s team has been talking to operators in the e-bike sector about their current battery disposal practices.
“They’ve been told by so-called battery experts … to just tape up the terminals and throw them in 160 litre wheelie bins for disposal collection. Now that’s just not good enough,” he said. “When I asked, were they discharging the batteries to a safe level? The answer was, in some instances: maybe not.”
Priestley said incorrect discharging of battery terminals could lead to big problems.
“In that situation, all it would take would be if you’ve got a battery with some charge remaining that touches another battery with terminals that haven’t properly been isolated or taped up,” he said. “Now you’ve had a short circuit and potentially a fire and dangerous situation.”
He said there’s also currently no standard practice for the disposal of faulty lithium-ion batteries.
“I’ve seen some companies throw them in big containers full of sand. But there’s no unified approach, as every battery product is different.
Despite the safety concerns, lithium-ion batteries are a crucial tool – and one we’re likely going to increasingly rely on.
Priestley said he’d like to see government regulation catch up to match the risks.
“The regulation is very non-prescriptive. Legally, we can store these things in cardboard boxes,” he said.
He said UNSW hopes to form a national working group underpinning a more coordinated approach to battery safety.
“What we’re seeing at the moment is every institution is doing their own research and has their own way of doing things. It means there’s a lot of duplication of work,” he said.
“We actually need a centralised approach and in particular centralised data collection on issues with lithium-ion batteries to dispel any myths surrounding these products.”
Better onshore testing facilities may also play a role in increasing safety. Kerr said Deakin University’s Battery Research and Innovation Hub is ramping up testing capability.
Priestley also wants to see greater public awareness of battery risks.
“We’ve been used to petrol and how dangerous petrol can be when used the wrong way,” he said.
“But we don’t have that level of intuition with batteries at the moment, despite the fact they have a similar risk level, if not higher.”
And, despite the challenges, Priestley is optimistic about the future state of play – and doesn’t want to warn people off lithium-ion altogether.
“Although lithium-ion batteries have these risks, they are a really good way of decarbonising our economy.
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