Sound Policy podcast: How research is confronting lithium-ion battery risks

Brian: Stephanie, can you tell us what you do at FM, what your job is, and how long you've been here for?

Stephanie: I have been with FM for 11 years and I currently am in the Chief Engineer’s Group within Fire Hazards and Protection. And I basically manage a number of our loss prevention data sheets as well as represent FM on codes and standards committees.

Brian: Ben?

Ben: This is my 23rd year. I'm in the research department, where I have been since I started back in 2003. I'm now the technical team leader of the large-scale fire team. So I'm tasked with developing large scale fire testing and I'd say probably over the last five or 10 years I've really started to focus on emerging technologies. Automated storage is a big one and pretty much anything you do with batteries, how you store them, what you do with them, including things like energy storage, but moving all the way into electric vehicles and all the different applications you can find.

Brian: Stephanie, you authored the data sheet on the storage and manufacturing of lithium-ion batteries. It was the first comprehensive guide to this. I know it's a very detailed data sheet and there's a lot of recommendations in there, but what are some of the highlights? 

Stephanie: I think the main takeaway from the data sheet should really be that you cannot stop thermal runaway once the battery goes into that.

Brian: Can you explain thermal runaway and explain how it starts?

Stephanie: So, thermal runaway is when essentially you create a short circuit within the battery cell itself, and essentially you are making that anode and cathode come into contact with each other because you're degrading the separator.

And that short circuit allows those two components to come together, which then triggers a reaction, which is exothermic, and starts to put off heat and that increases the temperature. And that temperature increase can't be dissipated. It increases at a faster rate than it can dissipate that heat. And so then you have the thermal runaway reaction.

Ben: It's the kind of question that you wake up at two o'clock in the morning answering – like what am I doing?

Stephanie: And the protection guidance that we provide is really about managing the fire once a battery goes into thermal runaway, and then also just limiting how many different cells do get involved in that fire. And so that we can control it to a point where we limit the overall damage to the property, and limit the event for our clients.

Brian: How risky are lithium-ion batteries?

Ben: There's a number that used to get quoted all the time. They said one in 10 million batteries fail. And I spent a day of my life trying to figure out where that number came from. It's not a number that was properly referenced anywhere. It was something that was provided in a report that somebody else then referenced, and then I went down that path of seven or eight references.

I was never able to actually find any primary research that developed it, even if it's true.  10 million batteries is not that many batteries. 10 million batteries, some of these energy storage systems are getting on that are getting on that number.  We know they happen. There's even trackers for that.

So even if they're not that common, every time one happens, a wide contingent of people and research and code and consulting, we all get the same email saying there's been another event. So it stays very present on your mind.

Brian: I did find a statistic, according to FM research, at least 44 lithium-ion battery fires and explosions were reported globally during a recent five-year period, that I think was until 2022. So 44 is not zero and when each individual loss seems like it could be a pretty significant loss. How do you limit that damage?

Stephanie: Mainly by providing copious amounts of water, which we learned through many of Ben's tests at the research campus.

Brian: Ben, talk about that testing. What does that look like?

Ben: I mean, it depends a lot on the different applications. If it's an energy storage system, then it could be up to an actual full size energy storage system.

The thing with batteries, scale matters. understanding what a single cell looks like in a failure mode is not the same as 10,000 cells together. And so if you're looking at a data center, it looks like a data center. If it’s an energy storage room, it looks like an energy storage system.

We're going to test these at full scale and then every scale in between, all the way down to the cell. So we understand basic physics up to the full hazard, and then we get that protection solution.

Brian: And, and by testing you mean setting them on fire in a lot of cases.

Ben: Set them on fire. Absolutely.

Brian: How do you do that?

Ben: It’s actually not that hard. All you have to do is heat them up.

Narration: We watched a video of one of their lithium battery tests.

Ben: Well, right now we're looking at the inside of our large burn lab, which is about the size of a football field with an 80-foot ceiling. So we have a large concrete test pad with a storage setup that's three tiers high. So that's 15 feet tall. We have carton lithium-ion batteries, which are in the white boxes, and then we have some target commodity we want to fill out. The test array gives us a better sense of fire spread laterally, but also if it would jump across an aisle space and move to another storage area. And so that's, that's the brown boxes.

Brian: Stephanie, would this look like a typical business' configuration of batteries in one of their facilities? Does this look pretty standard?

Stephanie: If they're using traditional storage methods? Yes.

Brian: You see a person in firefighter gear, just came in with some sort of blowtorch. What is that person doing?

Ben: Yeah. So that's our standard ignition process for a warehouse scenario. Basically we use a roll of gauze with a little bit of gasoline. It's just enough to get the cardboard burning.

Ben: They ignite that within the rack. And then once the cardboard starts to burn, you'll start to see that vertical fire spread, and you can see it here. Now we've started the first tier and now the flames, three, four feet above the top of storage.

Brian: Does it look, smell, sound any different than some wood pallets? Are there characteristics of a lithium-ion battery fire any different?

Ben: Smell’s a great question. It does have a distinct smell. Thermal runaway has a distinct smell when the chemicals are released. All fires themselves smell bad. Burning plastics, even from back in the seventies, were still thick black smoke.  Lithium-ion batteries have a distinct nature to them.

Here you have, I would say a small amount of smoke that's been produced from, from a fire.  It's important to note here, this is a lab. If this were an actual warehouse, that smoke would start to accumulate.

So even in a test that's producing sort of this whiter smoke, it starts to get difficult to see what you're looking at. If there were more plastics involved or if protection wasn't as effective here, you'd have thick black smoke. And it's not uncommon to completely black out your lab.

Brian: Wow.

Stephanie: And in lithium ion battery fires, one of the biggest loss drivers is actually the non-thermal damage that you get from all of that smoke.

Ben: So there we have our first micro operation. This is a large K factor sprinkler, so it has that high momentum push and you can see that. You can see it come down and you can see it kind of push the fire plume out of its way.  Now you have water cascading over the boxes, that's gonna help extinguish the cardboard fire. So now you can start to see that that fire is being suppressed. That means it's actually actively reducing in size, but there's still some consistent burning and that's in that ignition area. That's the part that's been burning the longest. It's gonna be the most difficult to extinguish. It's also the part that's farthest away from the sprinklers, so there's more obstructions to getting the water down onto that, that ignition area.

Brian: And so what were the results of the test?

Ben: This was a success. You can see the batteries, the shiny metal on the inside there. We did have thermal runaway, we did have batteries involved, but we didn't have a propagation beyond the batteries that were immediately involved.

So in this case, we are very happy with the protection and this is a relatively minimal amount of damage.

Brian: And, and Stephanie, what is it like to have your data sheet be supported with tests like this? Are these sorts of tests really important for your data sheet?

Stephanie: Yeah, definitely. I mean, this test actually was the first protection guidance that was offered originally in data sheet eight dash one, where we initially had our lithium ion battery protection guidance located.

But a few years ago we decided that this topic really needs its own standalone data sheet, so that's where we created data sheet 7-112. And we've come a long way since this test in our understanding through all the testing that Ben has described from the fundamentals of understanding the cell hazard to a group of cells to a module to the end use cases.

And through all that testing that we've done, we've been able to improve our protection guidance within 7-112 and offer that flexibility that the testing we do here allows.

Brian: Stephanie, I want to ask you, we've been talking about lithium-ion battery risks. Why do we use these batteries? If they carry these risks, why are they useful?

Stephanie: So with the world today, pretty much everything is based on portable electronic devices. Our cell phones, our watches, our laptops. And so with that increasing demand to be mobile and green. So even in this environment, we are trying to be greener and trying to increase mobility of everything. And so lithium ion batteries provide a means to electrify our world and we tend to go to them and there's an increasing demand because of the cost effectiveness of them.

And so we needed to provide the guidance that we have in 7-112 because of this increased demand that we're seeing in the world for these portable electronic devices that use the batteries.

Brian: What does make them vulnerable to fires and explosions?

Stephanie: Abuse. Everybody drops their cell phones. In storage you have fork truck drivers that could puncture them. It's really abuse, whether it's electrical, which is overcharging or just over discharging, mechanical like puncturing dropping or thermal, just exposure to high temperatures as Ben had mentioned, which is how we actually ignite multimillion battery fires.

Brian: How do building codes come into play here? 

Ben: She's right. It's relatively hard for a building code to keep up with technology. They run on three year cycles. Generally speaking, that means it takes six years from the introduction of a new technology for it to reach code. Obsolescence on a technology could be in three years. So by the time you're answering the question, the industry might be on to the next version of that technology.

This is not a battery problem. This is a consistent challenge as we move more and more into technology-based hazards.

Brian: It does seem though it's not specifically a battery problem, but maybe particularly a battery problem, given how common they are, and as you were saying, data centers, battery energy storage systems, it does seem like that's going to be a huge part of these future technologies.

Can you speak to that, how, how important they are to these new technologies that we have coming?

Ben: Sure. And it's actually not just batteries as a hazard. A lot of what I do is hazards that are enabled because of the batteries. Think of things like robotic storage. That concept of automated storage where if you order it today and it can show up tomorrow, it's probably a robot involved.

A lot of those are based on different types of battery technologies. So in some cases your hazard is your batteries and in some cases your hazard is enabled because you have access to those batteries. It's part of what 7-112 actually does is tries to separate those two things out. What is a battery fire and what is just a fire?

In some cases the batteries kind of like a match, and what might cause the fire. But something like storage density in a warehouse – That might not be a battery hazard, that's enabled by the batteries. Whereas something like an energy storage system, there you’re predominantly batteries plus the cabling and all those. But we know how to protect cables. It's that battery component we need to understand.

Brian: I think there was some reference to state of charge in the data sheet. Why is the state of charge of a battery important and, and how does it play a role in whether or not a battery will go into thermal runaway or not?

Stephanie: So at higher states of charge, it's easier to trigger thermal runaway, because there's, there's more energy there and it's, it's easier for that battery to, to go into thermal runaway creating a more intense fire.

Whereas at lower states of charge, it can be difficult to get them to go into thermal runaway. And then when they do, the fire isn't as intense as you would for the same exact battery at say a hundred percent versus 30% state of charge. And that's also one of the reasons why you see, a lot of transportation regulations coming out with a threshold of 30% state of charge.

Brian: Transportation– if you're shipping these batteries, they have to be at a lower state of charge. 

Stephanie: Yes. Yep.

Brian: As the batteries are getting bigger, is this risk getting bigger?

Ben: Yeah, this sounds a lot like our internal questions that we have within research all of the time. If you take a box of one size and you put a thousand batteries into it, or you put a hundred batteries into it with the same amount of energy, does it make any difference?

And right now that's ongoing research, but it looks like it's actually not that impactful, because you only can get so much energy into that box. And so that's, that's part of being agnostic in our guidance that we're trying to get down to. And, right now we're actively looking to see if we have to worry about the individual size of each battery.

Stephanie: And as far as quantities go, part of our guidance is really to limit the overall number of batteries we get involved, and that all plays a part in the duration of these fires. Because what you'll hear on the news a lot is it took five days, six days and that's because of the batteries, that thermal runaway cascading to adjacent cells and continuing on. And so that can just increase the duration of the event.

Brian: Stephanie, how do you conceive of the risks of lithium-ion batteries in your own personal life? Somebody who has obviously dedicated a lot of time to understanding the risks. When you see one in the wild, when you get on a plane and they say you can't have your power bank in the hold, how do you conceive of the risks and explain– put them in context for people.

Stephanie: Well I'll definitely say I'm much more aware of the risks now, whereas before, I just carry my phone and my laptop and I wouldn't think anything of it. Now I take my phone, my laptop. Those are kind of more calculated risks that I'll just, I'll have them charging in my house, but the bigger batteries that go into the lawn equipment or whatever, those get charged outside now away from the house. I don't leave them charging overnight like I would have before

Brian: Really. Wow. Ben, same, same. Do you take the same sort of practices?

Ben: I do 100%. I actually use this anecdote sometimes when I present, we as researchers, but also just in the community, know that you can damage a battery. It is really simple. If you just take a nail and puncture or a lithium-ion battery, it will go in a thermal runaway. It will vent flammable gases. If you drop your cell phone on the ground, aside from being very upset with the screen that the screen broke, you'll probably put it back in your pocket and walk away. So, that's the interesting part about risk. Sometimes we know better and we still do the wrong thing.

Brian: If you dropped your phone and your screen broke, would you put it back in your pocket?

Ben: I have put it back in my pocket!

Stephanie: I have as well. And we've had losses where basically during manufacturing the robot malfunctioned and basically just dropped a tray of lithium-ion batteries on the floor and there was the fire because it mechanically abused them. And so it's a real hazard that could happen. But we take that for granted because it's an everyday device that we're all attached to.

Brian: Stephanie, for businesses that may be listening to this podcast, is there one thing that they could do if they're concerned about their exposure to lithium-ion battery fires?

Stephanie: Okay, the first thing they can do is really look at where their exposure is and understand the hazards, and then they can start to take a look at, if they're a manufacturer at 7-112, take a look at how they can start to look at protecting their manufacturing processes as well as limiting their storage and their state of charge where they can.

And then for the storage, they can also go to 7-112, data sheet 7-112, to see what are the different protection options there based on how they're packaging that battery. Because, as Ben mentioned, it all comes down to what is going to be driving this fire hazard. Is it the battery or is it all the other stuff? All the packaging and everything that the battery may be in.

So that could also drive how they package their battery, right? If they're using cardboard, that's going to be, a good media that's going to set off their sprinklers right away, it's going to absorb that water. But if they're going to use expanded plastic, that's going to definitely increase their fire hazard and require more robust protection.

So understanding how their packaging is going to also play a role in impacting their hazard could be important when they're looking at the lithium-ion batteries in their facilities.

Brian: What about data centers to pick that out in particular? If there's a data center business out there that has these battery backup units that are now even more integrated into the system.

Stephanie: So for data centers, those would actually be covered by data sheet 5-32. and I think each rack has to be less than or equal to 20 kilowatt hours in order to follow the guidance that's in that data sheet. Otherwise, we would consider it an energy storage system and it would have to follow the guidance in data sheet 5-33.

Ben: And this is part of the challenge that we kind of touched on a little bit before. The data centers that had a small amount of batteries in each rack, that's, that's a type of hazard. But as these power requirements get greater and greater, now we have clients that want to put more and more energy into the racks and all of a sudden you're transitioning an occupancy that looks the exact same, right. A data center, with a bunch of server racks and a data center with a mix of server racks and battery racks fundamentally look about the same, but they don't represent the same hazard, and we have to go about the testing completely different for those.

Brian: Same question I just asked Stephanie, I think you hit on this a little bit, but what is one or two things that a business can do if they're concerned about their exposure to lithium-ion battery risks?

Ben: I'm going to answer the question a little bit, sideways. Just, just, just for fun here. So we've been looking a lot at, at loss exposure, to understand what is the actual main driver of the loss? And something like a data center – we use copious amounts of water, right?

That's our data sheets all say copious amounts of water. No one really wants a sprinkler to operate in a data center. Even if it does its job perfectly, the mere fact that sprinkler operated just caused a lot of physical damage. It's also a potential driver of a business interruption.

So we're trying to blend active automatic protection, things that we know will protect the building, things we know will provide that level of protection we're looking for, with things like passive barriers. 

In this case, lower the risk, but lower the frequency. 

Brian: What advice do you have just for everyday people about their use of lithium ion batteries?

Stephanie: Well, just like Ben said, just be aware of the hazard. And make sure, especially with your larger battery packs for your lawn equipment and things like that, you're charging them outside, and then just be aware for those, those smaller ones that you wear on your person, like your watch or your cell phone.

Brian: I'm going to go home and unplug my lawnmower.