Lithium-ion battery safety in question

Fears have been raised about the safety of lithium-ion battery technology in cars and houses after the four-day fire at the Victorian Big Battery facility earlier this week.

The fire broke out in the Big Battery’s Tesla Megapack lithium-ion system near Geelong last Friday morning and was finally brought under control on Monday afternoon.

It sparked calls for people in Batesford, Bell Post Hill, Lovely Banks and Moorabool to stay in their homes, close all windows and bring their pets inside as a toxic cloud of smoke drifted overhead.

More than 30 fire trucks and support vehicles and about 150 fire fighters from the Country Fire Authority and Fire Rescue Victoria contained the fire to just two of the 210 or so Tesla Megapacks that make up one of the world’s biggest battery energy storage installations.

Fire crews then remained on site to ensure damaged equipment would not reignite and an investigation is now underway to find the cause of the fire.

The fire in the 13-tonne battery burned out of control before it had even started operating, forcing the CFA, which admitted to having no experience in lithium-ion fires, to call everybody from Tesla to Panasonic for advice on how to extinguish the blaze.

The 300MW site, run by the Australian offshoot of French energy giant Neoen, was only registered as an energy operator on July 28.

“This is the first Megapack fire that’s ever happened in the world, is our understanding,” CFA incident controller Ian Beswicke said in a statement.

Except it wasn’t.

There have been 38 of them since 2018, according to Newcastle University (UK) lithium-fire expert, Professor Paul Christensen, with the last large one in Beijing in April needing 235 firefighters to extinguish, killing two of them.

They’re becoming frequent events, but the truly frightening thing is that nobody really knows how to put them out effectively.

“We don’t have a definitive answer as to the best way to deal with EV fires or energy-storage fires,” prof Kristensen told the Financial Times.

“It [lithium-ion technology] is essential for the decarbonisation of this planet. [Yet] its penetration into society far exceeds our actual knowledge of the risks and dangers associated with it.”

And that’s where the danger lies, because EV drivers are sitting on top of these batteries, with most EV makers containing them in the floors of their cars.

Australian CFA firefighters took advice from experts including the battery supplier Tesla and UGL, which installed the battery packs.

“The recommended process is you cool everything around it so the fire can’t spread and you let it burn out,” Beswicke said.

Oddly, the CFA’s official statement on the fire first stated the site used Tesla batteries, then later removed the reference to Tesla, then deleted the statement altogether.

But experts have warned that people should be aware of the risks of the current generation of electric cars and SUVs being powered by the same lithium-ion cell chemistry.

Brisbane’s Graphene Manufacturing Group (GMG), which is pioneering graphene-aluminium battery technology, suggested people would be shocked by what they found if they scratched the facade of the environmental advantages of lithium-ion mass production.

“There needs to be clarity about the risk of scaling lithium-ion batteries in some applications,” GMG CEO Craig Nicol told carsales.

While that may be taken with a grain of salt from a company with a patented, alternative cell chemistry, Nicol has a point.

One accepted environmental issue is that it takes just one faulty cell to makes the rest of the cells not just useless, but potential fuel. That means, for example, it takes just one cell out of a pack of 1000 cells to junk 999 perfectly good cells, because they all need to work at similar levels.

“Every lithium cell in a battery pack is critical, the balancing is critical, the heat load is critical and the performance management is critical – as some battery fires have shown,” Nicol insisted.

There have already been fire concerns with Tesla, Audi and Porsche EVs. The German makes recalled and repaired their cars instantly, while Tesla issued an over-the-air update to address thermal runaway concerns in 2019 (though that lead to a US National Highway and Transport Administration investigation into the range reduction it caused).

Tesla has since been forced to recall its cars in China over thermal runaways, though it refuses to do so in the US.

Nobody in the car industry, in particular, is in love with lithium-ion as a long-term technology, but it’s the only way that Paris 2050 greenhouse-gas emission targets can be met, and it’s the only way they can meet EU7 CO2 emissions demands this year.

Toyota isn’t a fan of the lithium-ion cell chemistry, preferring nickel-metal-hydride for the vast majority of its hybrid vehicles, and hopes to leapfrog the entire lithium-ion era and land with hydrogen fuel-cell EVs.

But even the world’s biggest car-maker couldn’t jump far enough, and it has been forced to follow the lithium-ion path for its plug-in hybrids.

So that makes… every full-EV maker.

Audi, BMW, Daimler, Volkswagen, Skoda, Seat, Bentley, MINI, Peugeot, Nissan, Renault, Mitsubishi, DS, Citroen, Jeep, Ford, GM, Jaguar Land Rover and a very long list of Chinese car-makers all use lithium-ion technology for EVs.

With all current EV architectures engineered around lithium-ion batteries, and those architectures surviving for up to two full generations of each model, companies could be locked in to the technology for at least 20 years.

“Lithium-ion problems and limitations are understood, but using a new technology in automotive, unless you can bolt straight into the space created in the architectures for lithium-ion batteries, you won’t get in,” Nicol admits.

“We can come into those guys and drop in with an interchangeable battery pack, but it will take a while, and it will take a substantial amount of money to get there, too.

“There will be hesitance, because they won’t want to change, and every new battery factory committing to lithium-ion locks that industry in more and more.”

The number of battery patents lodged at the European Patent Office has grown four times faster than any other area of technology since 2005, with the highest penetration being for solid-state batteries.

Nine of the top 10 battery patent holders are Asian, lead by Panasonic and Toyota from Japan, then Samsung and LG from South Korea and Germany’s Bosch.

Toyota itself holds more than 1000 solid-state battery patents, while Samsung is claiming 800km of range and more than 1000 charges of life cycle. Modern lithium-ion batteries begin to lose their capacity after fewer than 70 charges.

With lithium-ion the only production-ready game in automotive, European rules that mandate EV usage also effectively mandate lithium-ion usage.

Battery makers on three continents have committed to lithium-ion production, with the biggest suppliers including China’s CATL, A123 Systems and BYD, South Korea’s LG Chem, Samsung SDI, Japan’s Toshiba and Panasonic (which makes Tesla’s cells).

The battery cells are also able to be recycled once their automotive life is over, to be converted to domestic energy storage. Volkswagen, Porsche, Audi, Mercedes-Benz and BMW all offer this, while Tesla does it with new cells.

All of this means a lot energy either sitting inside in garages or attached to houses all over the world, with a chemistry that even NASA admits can’t be made 100 per cent safe.

The Big Battery crisis isn’t the first non-automotive lithium-ion issue. Organisations from NASA to Boeing have all seen lithium-ion as both a savior and a curse.

The first hint that something wasn’t right came when a Boeing 787 Dreamliner caught fire in Boston in 2013 with a lithium-ion thermal runaway, then another one caught fire at London Heathrow and there were several other minor incidents.

The entire Boeing 787 fleet was grounded in 2013 – the first time that had been done to a commercial airliner since the McDonnell-Douglas DC-10 in 1979.

NASA specialist Dr William Walker quickly twigged that a lithium-ion thermal runaway in space would be a very bad thing, so the NASA Engineering and Safety Center led the way to figure out the problem.

“Like most industries, NASA also uses Li-Ion batteries,” Dr Walker said in an interview with the Battery Power Online publication.

“However, we operate in an arena that can be especially high-cost and high-risk, and those risks have to be addressed.

“We didn’t choose to ignore thermal runaway, nor did we try to develop a standard that requires us to completely prevent thermal runaway altogether [at a fundamental level that’s not possible anyways].”

Essentially, that’s NASA insisting that lithium-ion thermal runaways are impossible to eradicate, which is frightening enough.

“An effective thermal management system can make sure that thermal failure does not happen,” Dr Walker explained.

“A first-rate structural design effectively ensures a mechanical failure will not occur. Instituting effective battery management systems prevents electro-chemical abuse situations.

“What can’t be prevented is the possibility of a latent defect, of foreign object debris, or of something in general being inside the cell that can cause an internal short circuit.

“Therefore NASA chose to start assuming that thermal runaway could happen, and would happen, and then to design a thermal management system that both prevents this from being a catastrophic event and also prevents cell-to-cell propagation.

“In other words, we assume it will happen and we plan for it, we give the heat somewhere to go, and we have a thermal management system designed such that when heat is released it doesn’t force a neighboring cells into thermal runaway.”

There is not one simple answer to why lithium-ion batteries begin to burn, but there is a simple answer to why they continue to burn.

The hotter they get, the more they burn, and the more they unlock their own oxygen to burn even hotter.

“The fire in this particular lithium-ion battery [the Victorian Big Battery] could be caused by anything,” the Graphene Manufacturing Group’s Chief Scientific Officer Dr Ashok Kumar Nanjundan said.

“It’s usually that over-charging the battery causes thermal runaway and decomposition of the electrolyte, which spirals into an exothermic reaction and eventually the battery catches fire.

“This could happen in any lithium-ion batteries, whether from short circuiting or electrochemical abuse [like over-charging].

“At an elevated temperature an exothermic decomposition occurs and the self-heating rate goes up, with the heat dissipating to the battery coolant systems, but at this stage there is no stability in the cell anymore and it spirals into an eventual cell fire.”

NASA’s Dr Walker explained it further, suggesting there are inherent issues with the lithium-ion cell chemistry.

“When a Li-Ion cell, or a small spot within the cell, reaches a certain critical temperature range, the materials inside the cell start to break down, to decompose.

“These decomposition reactions are exothermic in nature [they give off heat], which is why we have a self-heating behavior.

“Further, the decomposition rates, which are directly proportional to the exothermic self-heating rates, follow Arrhenius form, which means that the decomposition rate [and subsequently the self-heating rate] goes up exponentially as temperature goes up.

“Put simply, as the temperature increases, so does the decomposition rate, and likewise, so does the self-heating rate. The result is a self-feeding heating rate within the cell that increases until the cell loses stability, ruptures, and all remaining thermal and electrochemical energy is released into the surroundings.”

But while it’s easy to predict that cell chemistry will fail, each failure is its own story, Dr Walker insisted.

“No two thermal runaway events are alike. When considering thermal runaway for a given cell, one shouldn’t consult a single experiment, or two or three experiments averaged together,” he insisted.

“Decomposition reactions can go to different levels of completion. Sometimes the cell doesn’t fail out at the top or bottom the way it’s supposed to.

“Sometimes there’s a sidewall rupture or a spin group breach. Sometimes there is a bottom rupture for a cell that’s not a bottom vent cell.

“Each of these failure modes leads to a different thermal response.”

American fire authorities have reported that fighting Tesla battery fires can require more than 100,000 litres of water, which is significant in a dry country like Australia.

Tesla’s own Emergency Response Guide for the Model S recommends the use of “large amounts of water” of between “3,000-8,000 gallons (12,000 to 32,000 litres)” and also recommends that emergency services closely monitor the battery for “at least 24 hours” after any fire.

America’s NNBC news quoted a fire department chief Palmer Buck describing a Tesla battery fire as “a trick birthday candle” after it reignited multiple times.

That fire needed 110,000 litres of water to extinguish, with Buck insisting it only takes about 1100 litres to put out a fire in a combustion-powered car.

Tesla’s battery fires might stand out because it was the first one through the door, but it also stands out for its refusal to issue recalls for thermal runaways anywhere but China, where it was forced to.

But the emergency response guides for every EV-maker are shocking to read, and their water consumption must come as a surprise to rural firefighters, in particular.

The Volkswagen guide for the ID.3 and ID.4 gives firefighters two options: drown the batteries or let them burn out.

“Use large amounts of firefighting water,” the Volkswagen guide insists.

“This will cool down the battery from the outside and water can enter the battery through the openings.

“It may also be necessary to notify the sewage treatment plant and the competent environmental agencies.

“Another option is to let the lithium-ion battery burn under control in the vehicle that is no longer on fire.”

A third option, according to Volkswagen, is to submerse the vehicle in water to cool the battery pack.

That’s a strategy Tesla warns against, but European fire agencies have begun loading up on waterproof shipping containers to turn into EV bathtubs.

Section 3-3.3 of the Nissan LEAF guide specifically warns against using small amounts of water to extinguish a battery fire [with ‘DO NOT’ in capital letters, and Tesla does the same thing], insisting a fire hydrant must be used.

If a LEAF hasn’t caught fire in a convenient location, though, it is to be drowned in whatever water is at hand.

That’s not enough for the US National Transport Safety Board, which also governs plane crashes, and it put out a report late last year insisting EV first-responders’ guides were not sufficiently detailed.

“The instructions in most manufacturers’ emergency response guides for fighting high-voltage lithium-ion battery fires lack necessary, vehicle-specific details on suppressing the fires,” the NTSB warned.

Not that the NTSB has covered itself in glory on thermal runaways. It took nine years after Tesla’s 2008 launch for the NTSB to investigate its first Tesla lithium-ion fire, in August 2017.

There are several alternative technologies on the horizon, but none are viable for mass-production EVs today, other than abstinence.

Some scientists insist on waiting out lithium-ion, like University of Birmingham research fellow Gavin Harper.

“It is essential that we don’t stifle new innovation as it is imperative that we decarbonise rapidly, but at the same time, we need to take a precautionary approach as we deploy new technologies at scale,” he surmised.

Yet the list of the looming chemistries is large and includes graphene aluminium batteries from Brisbane’s Graphene Manufacturing Group and Stanford University, graphene supercapacitors, lithium-sulphur, redox flow, solid-state and thin film, plus hydrogen.

The most obvious has been hydrogen fuel-cell EVs, which push hydrogen across a fuel-cell to create electricity and water vapour, only one of which is then used to drive the electric motor(s).

But experiment and prototype as Audi, Volkswagen, Mercedes-Benz, BMW and Honda might, only Hyundai and Toyota have been brave enough to bang out full-production fuel-cell cars.

As of December last year, just 31,225 passenger FCEV cars have been sold around the world.

The big problem remains that energy companies would need to use fossil fuels to break hydrogen free of its earthly bonds to generate enough of it to power mass-production fuel-cell EVs.

So far, it’s self-defeating.

Stanford University made people sit up and notice graphene-aluminium batteries, with charging rates of a minute for a smartphone and only a few minutes for an EV, but the 1.5 volts they worked with isn’t enough for anything terribly useful.

“With ours right now, we think we can get to 1kWh per litre with our pouch pack at sometime in the near future,” GMG’s Nicol insisted.

“The power density [the ability to charge fast] is really exciting, and what’s also really exciting is volumetric energy density: the kW hours-per-litre.”

Also, an extrapolated long-haul truck battery would take no longer to recharge than a conventional truck would take to refuel.

The other upside of graphene aluminium batteries is that they don’t overheat, they are light, much safer and have potential for improved energy density and volumetric density.

Lithium-sulphur batteries are delivering 40 per cent more energy density in laboratories, but their main issues include electrodes that degrade far too quickly for automotive use.

Graphene supercapacitors charge and discharge far more efficiently than batteries, but they hold less energy for their volume. If it can be cracked, it becomes a game changer because they’re even wearable.

Deep in the laboratories of the US’s Pacific Northwest National Laboratory, scientists are working on a Redox Flow battery that uses both hydrochloric and sulfuric acid, and they claim to have 70 per cent more energy density than lithium-ion batteries.

They could power cars for well over 1000km for the same storage volume as current lithium-ion batteries, for example, but are mainly being developed for domestic storage and battery farms, like Victoria’s.

Solid-state batteries have been seen as a holy grail, even with lithium, because they would be far safer, with far more energy density and better charge and discharge rates.

They will be production realities within the next two to three years for Toyota, Geely, Mercedes-Benz, Volkswagen, Porsche, Audi and BMW.