Effluent when Lithium Batteries Fail 3

[Sparweb]

Hello,

What exactly comes out of a lithium battery when it is being overcharged or overheated? Has anyone measured the composition, exactly?

I am in the process of certifying the installation of Lithium batteries in an aircraft. There are some details of this process that I cannot and should not share with the forum, but I have questions about them that neither the battery manufacturer nor the FAA can answer. Hopefully we can get through our Q&A without needing me to describe the entire history of lithium battery installations in the aviation industry for the past 25 years. I hope it's enough that everyone knows they're great, until they aren't, and then they're a problem.

I have been working closely with the battery manufacturer on this project but they can only answer questions to which they know the answers. The manufacturer has done failure tests according to the design standards they must meet. However those design standards don't require measuring the waste products that escape during one of these failures. They didn't need to mount a gas analysis system to the vents of one of their batteries, drive it to failure, and measure what comes out. This means a vital piece of information for me, the installer, is not collected during the melt-down tests.

From a regulatory standpoint, as the installer I am responsible for protecting the aircraft from any products that are emitted from the battery when it fails. I don't get to decide that it won't fail, or how likely it is to fail. Those aren't options permitted by the regulations. Instead I have to make provisions to protect the aircraft from any products from the battery, be they hot or cold, corrosive or neutral, flammable or inert. Having no definition of the waste emitted through the vent I have no choice but to vent it overboard and keep it from running back to harm something else downstream. Remember this is on an aircraft, and if it's liquid it will flow from the battery drain and probably stick to the skin for a long way back. And if it's a flammable gas then it can't come close to anything with a spark (like motors with brushes).

This puts a lot of constraints on the places these batteries can be installed and the protections that go with the battery installation. But I feel like I'm working in the dark, protecting the aircraft (and sometimes its occupants) from harms that may not be realistic. Or worse, due to my ignorance, not doing enough!
Has research been done that tests the failure conditions and reports specific constituents of the effluent?

 

[3DDave]

This more of a chemistry question I think and a sore spot for me, having been grilled over what might happen to a lithium primary COIN cell that the EEs had selected because the double-wall aluminum test box would be shipped in a plane. Because there are any number of wrist watches using the same cell on passenger wrists had previously NOT exploded.

It may come down to a 55 gallon drum, an ignitor squib, and a li-ion cell, and capturing the resulting output and heading to the gas chromatography lab to see what is left in the barrel. Probably need a baseline with just the squib as well.

AFAIK the organic solvent is the same across li-ion cells, but the insulation and plastic for seals and so forth will complicate matters.

The nastiest stuff is HF gas so don't inhale. Apparently the lithium is tied into Lithium hexafluorophosphate.

Maybe helpful:

https://www.abebooks.com/servlet/BookDetailsPL?bi=31473272521

Lithium-Ion Battery Chemistries: A Primer
Warner, John T. (the book, not the specific listing)

https://www.nature.com/articles/s41598-017-09784-z

Toxic fluoride gas emissions from lithium-ion battery fires

https://publications.iafss.org/publications/fss/8/375/view/fss_8-375.pdf

Lithium Ion Battery Fire and Explosion

https://www.osti.gov/servlets/purl/1502653

Understanding Lithium Ion Battery Fires (thermal, not chemical)

 

[IRstuff]

There's some literature on the web:

https://iopscience.iop.org/article/...The released gases were analyzed,CO and H2 do

https://www.osti.gov/servlets/purl/1574807

https://go.gale.com/ps/i.do?id=GALE...atteries do not,are both flammable and toxic.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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[TugboatEng]

I had heard about the acid gas (HF) emissions from lithium batteries. I could never find any halogens in the construction. Membranes seem to universally be some type of polyethylene. I never thought of looking at the electrolyte.

Curious, most talk I see is that dangerous HF is only formed when the battery comes in contact with water so it is advised to not use water on li-ion batteries for that reason. I guess this is where engineers and biologists diverge in knowledge because there sure is a lot of moisture in our lungs, where the damage from HF is done.

 

[3DDave]

HF becomes hydrofluoric acid on contact with water, such as in lungs. Hydrogen will be available from hydrocarbons in separators and insulators.

The results have been validated using two independent measurement techniques and show that large amounts of hydrogen fluoride (HF) may be generated, ranging between 20 and 200 mg/Wh of nominal battery energy capacity. In addition, 15–22 mg/Wh of another potentially toxic gas, phosphoryl fluoride (POF3), was measured in some of the fire tests. Gas emissions when using water mist as extinguishing agent were also investigated.

from

https://www.nature.com/articles/s41598-017-09784-z

 

[EnzoAus]

In my work with small Battery Energy Storage Systems, I've also sought to find the byproducts of lithium cells during heating and particularly, thermal runaway. A 2023 paper by Chen et al provides data for LFP and NCM lithium batteries after thermal runaway, focusing primarily on combustible gases such as H2, CH4 etc.

A second paper by Larsson et al in 2017 gives some information on Hydrogen Fluoride (HF) gas generated during battery fires finding that it ranges "between 20 and 200 mg/Wh of nominal battery energy capacity".

Although I haven't fully read the papers, they're attached in case they are of value.

 

[EnzoAus]

And the second file

 

[Sparweb]

Thank you to everyone - that is exactly what I need. My intent was not to build my own test chamber, but to to see if this had been done already. Clearly so.

The products of thermal runaway (TR) are worse than I thought.

For everyone's comfort, the LI batteries I'm looking at will be installed in an unpressurized compartment, not within the passenger cabin.

COIN cell

Oh, just don't get me started.

 

[Sparweb]

Note that I also found a FAA test report about extinguishing LI battery fires with typical Halons (like HFC 1301, the most popular one in aviation).
It turns out that once the LI cells were ignited, the 1301 had absolutely no effect. The result was so surprising they weren't equipped to measure what was going on. The report speculates that the Halons might have been involved in the combustion, in fact.
If anyone wants to read, I'll post a link.

 

[TugboatEng]

Has Halon 1301 been used in new construction in the last 30+ years? We've been using a product called FM-200 in the marine industry for decades. The Halon ban did lead to a lot more CO2 systems being installed which I despise. Accidental discharges happen and there is always some Rambo that wants to run down into the space to investigate despite education.

I have heard that diesel engines can run on Halon so the trip before deployment is critical. The Halon also attacks the engine bearings in the crankcase (lots of water in there).. There was a report at one point but I don't know where to find it now. Hot Halon and FM-200 both produce acid gasses.

 

[IRstuff]

I've got a healthy respect for HF, in the acid form; it's the only acid that eats silicon dioxide, and it was a staple of the wet chemistry processing of semiconductors a gazillion years ago. It was NOT something to be trifled with; we used to stick our hands in HCl and nitric acid, but HF wouldn't exactly eat your flesh, it supposedly would migrate to your bones and the pain from that was supposedly bad enough you'd want to chop your hand off.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[Sparweb]

Aviation (military and civilian) got an exemption from the Montreal accord, if that's what you're thinking of Tugboat. Halons are a double whammy. They destroy the ozone layer, and they are about 1,000 times more effective than CO2 as a greenhouse gas.

That exemption could expire any time. Soon after that, a million aircraft fire suppression systems will stop working. Shortly before that, the FAA will be inundated with a million requests to extend the replacement intervals for fire extinguisher bottles.
About 5 years after that, some parts of the world will suffer aircraft accidents with cabin/cargo fires that can't be extinguished (and people will die). Meanwhile, in other parts of the world, multinationals like UTC will be touted as heroes by the environmental lobby for their work to "convert the world fleet of aircraft to non-ozone depleting gases".

Note: every aircraft that is designed and certified or converted to carry cargo with a halon-based fire extinguishing system *should* have its extinguishing system tested. Which means hundreds of pounds of Halons released into the atmosphere strictly for the purpose of testing, each time. Since the vast majority of aircraft never have a fire, I suspect the major cause of Halon venting by aviation industry is the testing, not the actual suppression of fires.

 

[TugboatEng]

I have vessels with Halon and FM-200 systems. A nitrogen tank operates all of the valves and switches in the system. During testing the discharge valve from the suppression tank is disconnected from the nitrogen pilot. The discharge valve is not tested. The liquid level in the tank is measured using a magnetic gauge. We have had one system self-discharge to 50% liquid level between tests.

 

[EnzoAus]

Argonite is another fire suppression that I recall used in the distribution industry. It is a 50:50 blend of argon and nitrogen which was designed to reduce the oxygen concentration below the point at which the fire could be sustained, whilst apparently maintaining enough oxygen for human survival.

An article in

https://www.powermag.com/lithium-ion-batteries-a-potential-fire-hazard/

mentions Argonite (& also FM-200 & Novec 1230) and lithium batteries. It states that "Gaseous agents will extinguish flames due to burning leaked electrolyte but have little or no effect on mitigating or preventing a thermal runaway occurring within Li-ion cells". It seems that the best defence is isolation from other combustibles and people, not easy on a plane.