Are lithium batteries safe?

[Brian Ellis]

http://www.bbc.co.uk/news/world-us-canada-11505505

Bulk shipments of the batteries are already banned from passenger aircraft, the agency said.

The agency said a United Parcel Service flight that crashed near Dubai last month was carrying large quantities of lithium batteries.

Above all:

The US airline regulator has warned carriers shipments of lithium batteries may ignite if exposed to high heat in flight, risking a "catastrophic event".

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Let's extrapolate this to EVs. An EV with a 400 V drive circuit has anything from 250 to 125 large Li cells (depending on the technology) in a compact unit. Is this tantamount to "Bulk" (ie in "pails")? Possibly more so, remembering Li is a highly reactive alkaline metal in its own right, burning with a dazzling white flame (compounds are spectroscopically crimson-red).

I assume the journalist knows not the difference between heat and temperature (typical!), but what is the high temperature it could be exposed to in flight? I think it can be assumed it would be nowhere near the engines, nor near the nose cone of a supersonic flight. A non-air-conditioned pressurised hold or cargo space would hardly reach 40°C. But an EV car parked in the sun in the Arizona Desert, in a Riyadh street or even in a supermarket car park in this country could easily reach 60°C (this summer, we had 46.2°C shade temperature here, even though it is a small island).

Kaboom??????

[TransformX]

Well, batteries went in flames in all kinds of devices before, from iPods to laptops. As long as the one in one's pacemaker doesn't fail, we're relatively safe I suppose.
Per the article, I'm not too crazy about current generation EVs. I think I'd rather see an almost pure internal combustion engine with an added oomph from a small, lightweight electrical one that only gets juice from capacitors that get recharged from regenerative braking and shock absorbers, making the stored energy available for the next acceleration and that's all.
Safer, quicker, lighter, you name it.

[VJ]

Well, the UPS plane was carrying a large amount of lithium battery, but it is not stated they are what caused the accident... Now they are just playing it safe. It could have crashed due to some unrelated issue.
Your point on the heat of an electrical car is a valid one IMO.

Jaguar just showed a prototype that uses 2 turbines to generate electricity to power the car... Not sure if it is more environmentally friendly though...

I'm also not too much in favour of purely electrical cars; I see more potential in hydrogen cars (even though they are also not without issues at the moment). BMW has developed a hydrogen combustion engin, and Mazda even have a hydrogen Wankel engine; both just "burn" hydrogen like their fossil fuel counterparts burn gasoline. The usability of hydrogen is closer to electricity (refueling rather than recharging, ...), and the required infrastructure more closely resembles the current infrastructure.

[Dr Mordrid]

It really pays to fully read the FAA report.

The problem is with non-rechargeable lithium batteries (those 2x-8x lifetime throwaways) because when they burn the fire doesn't respond to conventional fire surpression systems.

On the other hand, lithium-ion rechargeable fires do respond to fire conventional surpression equipment.

Reason: different chemistries & construction.

[Brian Ellis]

You mean that the lithium is not really lithium, a HIGHLY flammable metal and that all the recalled batteries for explosion and fire generation were not lithium-ion??????? May I also remind you that 2Li + 2H2O > 2LiOH + H2 is an extremely exothermic reaction and 2H2 +O2 (from air) can be Kaboom, not forgetting that ion-speak is also water-speak, even if the water comes from the atmosphere.

I wonder how many EVs will end up as a pile of ashes (hopefully not the cremated driver/passengers) and twisted/molten metal before they realise they have a problem that will make Toyota brakes look like a peccadillo.

[Dr Mordrid]

Of course lithium can burn, but so can the Jet-A used to fuel the jets and APU's that provide the plane with power

The big problem with li-ion fires has been electrode degradation and the presence of tiny metal particles in the electrolyte due to older manufacturing processes, either of which could make the batteries go into thermal runaway. Another problem has been chemistries that produce oxygen at the cathode.

Improved production techniques takes care of the metal particles. Nanomaterial electrodes with much larger surface areas allow for less lithium/cell, further reducing fire risk and cost. Other improvements include fail-safe devices and chemistries that don't produce oxygen at the cathode.

Not the case for non-rechargeable cells whose construction and chemistries make them a greater fire hazard in aircraft, especially those using the lithium-thionyl chloride chemistry. If for any reason one shorts, internally or otherwise, they can go into a very rapid discharge & start a fire.

Then, as mentioned, there is the difference in extinguishing a battery fire. Li-ions will extinguish using normal techniques, but not so the non-rechargeables - which was the driving force behind the FAA warning.

[Brian Ellis]

http://www.popularmechanics.com/science/4282985

What dangers do lithium-ion batteries pose?

You can get six times the energy density in a lithium battery that you can in a lead-acid battery and two or three times as much as in a nickel-metal hydride battery. Any time you pack more energy into a smaller space, your safety concerns go up. All the lithium-ion systems being tested right now use an electrolyte that is flammable, so one of the safety issues that we are very concerned about is how these electrolytes can burn when the cells have been ruptured. They can also be heated to the point where the electrolytes break down into gases (my editing: hydrogen and oxygen) that the cells vent.

What kinds of abuse tests do you perform on the batteries to simulate real-world scenarios?
One of the mechanical-failure scenarios we test is a crush. We'll take a fully charged cell or a full pack and put it into a hydraulic fixture where we slowly crush the entire pack at a very controlled rate. We have temperature sensors all around the pack and real-time gas analysis to monitor the gases coming out of the cell. We test for flammability by using spark sources around the room to ignite the gases. Sandia also has a radiant-heat test facility where we can take a full battery pack, put it inside a system surrounded by quartz lamps and heat the pack to 932 F in about 60 seconds to simulate the entire pack being suddenly engulfed in flames.

Does your research suggest lithium-ion batteries are safe for cars?
Well, that's a difficult question, because no one has defined what safe means. The energies that can be released are certainly less of a concern than driving with 20 or 30 gallons of gasoline. Are there scenarios in which the battery may get into an accident or an environment that causes it to burn? Yes, it can burn, but you're not driving around in a bomb. There are some significant advances going on right now that are making these much safer to use.

Anyone unconscious in an accident doesn't need an explosion to be cremated. Electrodes could be deformed to penetrate the electrolyte, causing short-circuits. I tend to be sensitive to this since a hire car I rented in the UK with about 50 miles on the clock caught fire through an electrical fault and that was with a tiny ~40 AH lead-acid battery. It was a total write-off as a large extinguisher I borrowed from the company I was visiting was inadequate for the job (it needed a CO2 or powder type which were unavailable). To add insult to injury, it was a water extinguisher with chemical CO2 pressurisation and weighed a tonne. I could easily imagine that using such an extinguisher on a cracked Li-ion would be very dangerous.

Note that this concern did not stop me buying a hybrid. Why? Honda already had 10 years experience since they started selling the first Insight, which has NiMH batteries, without incidents that I could find. These are inherently safer. The battery pack does not get hot in use (very warm, yes, I guestimate less than 50°C max on heavy charge or discharge over several minutes of descent or ascent of steep hills, and it has a thermostated ventilator to extract excess heat from its housing,

Anyone here likely to buy a first generation EV with Li-ion? I would wish to wait several years (3rd generation) before taking the plunge; let others generate the hindsight.

[Dr Mordrid]

I noted that some li-ions generate h2 and also that electrode and electrolytes have changed, and this includes lower quantities of lithium. These techs are already 2+ generations past what's in tools and laptops, and in cars they include active monitoring and per-cell cutout features. The biggies, A123 in particular but also LG Chems, have even had spikes driven into theie cells without fire or other "dangerous" issues. Messy, but no foul.

That's why Daimler and GM feel comfortable putting them in their hybrid buses and why many makers are going to, or have alreay started to, transition from nimh to modern li-ions.