BU-304a: Safety Concerns with Li-ion

Learn what causes Li-ion to fail and what to do in case of fire.

Safety of lithium-based batteries has attracted much media and legal attention. Any energy storage device carries a risk and this already occurred in the 1800s when steam engines exploded and people got hurt. Carrying highly flammable gasoline in cars was a hot topic in the early 1900s. Battery makers are obligated to meet safety requirements, but there are shortcuts by less reputable firms and it’s “buyer beware!”

Lithium-ion is safe but with millions of consumers using batteries, failures are bound to happen. In 2006, a one-in-200,000 breakdown triggered a recall of almost six million lithium-ion packs. Sony, the maker of the lithium-ion cells in question, points out that on the rare occasion microscopic metal particles may come into contact with other parts of the battery cell, leading to a short circuit within the cell.

Battery manufacturers strive to minimize the presence of such particles; however, complex assembly techniques make the elimination of all metallic dust a challenge. Cells with ultra-thin separators of 24µm or less (24-thousandth of an mm) are more susceptible to impurities than the older designs with lower Ah ratings. Whereas the 1,350mAh cell in the 18650 package could tolerate the nail penetration test, the high-density 3,400mAh can ignite when performing the same test. (See BU-306: What is the Function of the Separator?) New safety standards are more relevant to how batteries are used and the UL1642 Underwriters Laboratories (UL) test no longer mandates nail penetration for safety acceptance of lithium-based batteries.

Li-ion using conventional metal oxides is nearing its theoretical limit on specific energy. Rather than optimizing capacity, battery makers are improving manufacturing methods to enhance safety and increase the calendar life. The real problem lies when in rare occasions an electrical short develops inside the cell. The external protection peripherals in such a case are ineffective to stop the thermal runaway when in progress. The batteries recalled in 2006 had passed the UL safety requirements – yet they failed under normal use.

There are two basic types of battery failures. One occurs at a predictable interval-per-million and is connected with a design flaw involving the electrode, separator, and electrolyte and/or manufacturing processes. These defects often involve a recall to correct a discovered flaw. The more difficult failures are random events that do not point to a design defect. It may be a fluke incident that is comparable of being hit by a meteor.  

Let’s examine the inner workings of the cell closer. A mild short will only cause elevated self-discharge and the heat buildup is minimal because the discharging power is very low. If enough microscopic metallic particles converge on one spot, a sizable current begins to flow between the electrodes of the cell and the spot heats up and weakens. As a small water leak in a faulty hydro dam can develop to a torrent and take a structure down, so also can heat buildup damage the insulation layer in a cell and cause an electrical short. The temperature can quickly reach 500C (932F), at which point the cell catches fire or it explodes. This thermal runaway that occurs is known as “venting with flame.” “Rapid disassembly” is the preferred term by the battery industry.

Uneven separators can also trigger cell failure. Poor conductivity due to dry area increases the resistance, which can generate local heat spots that weaken the integrity of the separator. Heat is always an enemy of the battery.

What to do when a battery overheats . . .

If a Li-ion battery overheats, hisses, or bulges, immediately move the device away from flammable materials and place it to a non-combustible surface. If at all possible, remove the battery and put it outdoors to burn out.

A Li-ion fire can be handled like any other combustible fire and for best result use a foam extinguisher, CO2, ABC dry chemical, powdered graphite, copper powder or soda (sodium carbonate).

If the fire occurs in an airplane, the FAA instructs flight attendants to use water or pop soda. Water-based products are most readily available and are appropriate since Li-ion contains very little lithium metal that reacts with water. Water also cools the adjacent area and prevents the fire from spreading. Research laboratories and factories also use water to extinguish Li-ion battery fires.

When encountering a fire with a lithium-metal battery, only use a Class D extinguisher as water reacts with the lithium metal and makes the fire worse. With all battery fires, allow ample of ventilation while the battery burns itself out.

During a thermal runaway, the high heat of the failing cell may propagate to the next cells, causing them to become thermally unstable also. A chain reaction can occur in which each cell disintegrates on its own timetable. A pack can thus be destroyed in a few seconds or over several hours as each cell is being consumed. To increase safety, packs should include dividers to protect the failing cell from spreading to the neighboring one. Figure 1 shows a laptop that was damaged by a faulty Li-ion battery.

Suspected Li-ion battery destroys laptop


Figure 1: Suspected Li-ion battery destroys laptop

The owner says the laptop popped, hissed, sizzled and began filling the room with smoke.

Courtesy of Shmuel De-Leon

When pressure builds up, the gas released by the venting process of a Li-ion cell is mainly carbon dioxide (CO2). Other gases that form through heating are vaporized electrolyte consisting of ethylene and/or propylene. Burning gases also include combustion products of organic solvents.

While lithium-based batteries are heavily studied for safety, nickel- and lead-based batteries also cause fires and are being recalled. The reasons are faulty separators resulting from aging, rough handling, excessive vibration and high-temperature. Lithium-ion batteries have become very safe and heat-related failures occur rarely when used correctly.

Simple Guidelines for Using Lithium-ion Batteries


Last Updated 2015-09-16

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On November 3, 2011 at 4:50am
JasonsRobot  wrote:

Lithium0ion batteries are safest just because their manufacturing process and techniques are truly based of professional use. Its hardly you hear of any heat failure of it. batteries promise long life time come with high percentage of energy failure.

On January 16, 2013 at 2:58am
antoinecoca wrote:

Would anyone know which certifications and norms the Li-Ion battery must comply with when imported in Europe?

On October 28, 2013 at 4:04am
Maria wrote:


I would like to know if someone has data about how hot could a Lithium ion battery culd actually burn? (for large scale fires).

Tks in advanced.

On May 28, 2014 at 10:10am
Louis wrote:

Can I charge Li-ION 4500mAh 3.7V Battery with my “regular” Ni-Cd / Ni-MH RadioShack charger, if so what setting works the best, if any.


On July 19, 2014 at 8:07pm
Brendon wrote:

@Louis:  Definitely not!  Li-Ion is a very different chemistry from NiCd ard NiMH.  Each chemistry requires the use of a charger specifically designed for it.

On July 31, 2014 at 4:43am
j wrote:

We have a lithium fire extinguisher at work… how does it do it? DHL will send batteries by air somehow… there needs to be a way to send batteries safely…

On September 22, 2014 at 8:29pm
BB wrote:

someone played a joke on me by putting a lithium ion battery for a power tool in my oven.  I didn’t know and preheated my oven to 450 degrees before I smelled the plastic melting and discovered it.  How dangerous was this?  Could it have exploded and injured me??

On November 4, 2014 at 8:07am
Dan wrote:

@BB: You should immediately cease contact with that individual and surround yourself with more intelligent beings.

On December 2, 2014 at 2:12pm
Pillow wrote:

I recently got myself Gameboy advance SP and it has Lithium Ion battery. Since it did not come with charger, my dad tried to charge it with home-made charger, he crafted it using old nokia phone charger. Soon, when I was alone home, I discovered that the battery was a bit bigger than before and it was pretty hot. I unplugged it inmediatly and my dad said that he will see if he can charge it on safer way. I would like to ask, should I get the new battery? Is using the same battery dangerous even if it goes back to its normal size? What should I do?

On December 31, 2014 at 9:21am
sp00zer wrote:

Get a new battery right away. Changing physical size is an indication of internal chemical change in the direction of failure. A battery like that should never be reused inside of a device.

On February 18, 2015 at 12:48am
Thomas wrote:

I’m constantly bing told that water is the way to extinguish Li ion fires. And yet fire suppression companies sell class D extinguishers and say that water is NOT the way to fight these fires. What are the facts?

On February 26, 2015 at 10:36pm
Richard A. wrote:

I work for a company that exchanges fire extinguishers in buildings. There is a battery test lab for an automaker that I am iffy about the right extinguishers. They want an ABC, but wouldn’t a Dry Chem Sodium BiCarb be better due to the corrosive factors?

On March 23, 2015 at 3:33pm
Rich wrote:

For primary cells with Lithium, absolutely do no use water. The lithium will react with the water and you will have even more of an issue on your hands. So 1 use coin cells and the like, Class D extinguisher.

For Secondary cells, especially ones that are part of a pack.Put out the flame with pretty much any of the listed extinguishers above then you want to use water and a lot of it. The amount of lithium in secondary Li-Poly and Li-Ion cells is quite low and won’t react. Your goal with the water is want to drop the temp of the surrounding batteries so they don’t overheat and vent.

On May 2, 2015 at 1:38am
khan wrote:

my child put samsung phone battery 3.7 v in warm cup of tea that i drank. After realizing it, i hurried and took it out. Some white solid was already there at electrodes. Now i worry for health concern specially bcza i m 6 months pregnant. I m drinking lot of water and vomited as well. What kind of chemical would have released in so short time and what else can i do now.

On May 16, 2015 at 2:37am
roland wrote:

i`m no doctor and also no chemist, but i wouldnt worry.  the white solid is probably some electrolytic result of the current flow through the tea/liquid, as it can transport electrons. i`m sure, that no inner (or even poisonous) materials from the battery have leaked into the tea and your health is not at danger

On May 21, 2015 at 1:21pm
David wrote:

“If the fire occurs in an airplane, the FAA instructs flight attendants not to use fire extinguishers but the use of water or pop soda. Water cools the adjacent material and prevents the fire from spreading. Many research laboratories and factories also use water to put out battery fires… Li-ion contains no lithium metal and does not react with water (lithium metal batteries requires different extinguishing methods).”

Ok, so I’ve learned to use water, not fire extinguishers, and Li-ion batteries don’t react with water.

Then it says:

“Use a foam extinguisher, CO2, dry chemical, powdered graphite, copper powder or soda (sodium carbonate) to extinguish a lithium-ion fire. Only pour water to prevent the fire from spreading as water interacts with lithium.”

Ok, so now I’ve learned the precise opposite - to use fire extinguishers, not water, and Li-ion batteries DO react with water.

Very confusing.

On May 22, 2015 at 11:43am
Cadex Electronics Inc. wrote:

Thanks David, We have updated the article to clarify.

On June 5, 2015 at 7:28am
Terri wrote:

Has anyone heard of any Samsung SDI Li-Ion batteries used in HP Compaq recalls?

On June 25, 2015 at 5:07pm
Rod East wrote:

I am a serving professional Senior Fire Investigator and would like further infomation regarding the failures and way to identify the failure within the Lith-ion batteries.

On July 3, 2015 at 6:22am
raj wrote:

i have a blackberry MS 1 battery that has bulged and cracked.

Is it toxic to me or anyone around me to handle?
Are there any fumes that may be released?

Should I continue using it? It works fine, although the charge runs out quickly

On July 16, 2015 at 6:52am
Sue wrote:

Do lithium batteries leak out?  They seem so toxic I am concerned about having them in the clock radio that sits right next to my head all night!

On July 28, 2015 at 8:39pm
Erika wrote:

Can I use a lithium motorcycle battery in a fiberglass toolbox under the seat? Or is this a big no-no? Thanks.

On August 20, 2015 at 12:58pm
gary monroe wrote:

Does anyone know of a Lithium Ion Battery Handling Safety presentation (ppt) or onsite instructor-led course?  My company deals with Li-ion batteries in a big way and need a good battery handling course.

On September 12, 2015 at 8:50pm
Malia Skinner wrote:

i come down starts to find my tablet destroyed i threw it away cause it wasent working anymore and my tablets battery came out and my brother opens the battery and thosed it in the trash and came to get it i wasent expecting until my brother was holding it all of a sudden it got hot and the next thing the long battery ligt on fire what was the cause of this was it because my brother destoryed ot or long enough exposure to oxygen? please help me answer

On September 18, 2015 at 1:00am
n.z wrote:

what’s the range of moisture that li-ion battery can be safe when we want to open it?

On October 21, 2015 at 1:53pm
Robert Dubé wrote:

@gary monroe
I came across this while looking for battery info http://excellbattery.com/wp-content/uploads/2015/02/Safety-Presentation-FEB-2015.pdf
This company also have some training available, look in the top menu for training http://excellbattery.com I am not relate to the company and do not know about the paid trainings.

On November 26, 2015 at 4:31pm
Robert Irvine wrote:

Can a cell phone explode in a steam room at the gym some people are using them more frequently I think it may cause burns or worse please help

On December 4, 2015 at 2:11am
Tonawr wrote:

QUESTION. IF YOU’RE CHARGUNG YOUR LITHIUM BATTERY AND OVER 4.300 (the point of pressure buildup). will the pressure go away after taking it off the charger, or will that pressure stay there, making it able to explode anytime I begin charging it?

On December 11, 2015 at 3:32pm
Roger Bohn wrote:

Raj: Swollen, cracked, broken, or holed lithium batteries: treat them as dangerous! DO NOT USE; DO NOT RECHARGE. Even if they don’t burn your house down (happened to a friend of mine) they cause an unholy smell when they burn, which is very hard to get rid of.

Tonawr: Not sure what pressure you are referring to. Are you talking about the Amp-hour (charge) level? In that case, if you continue to charge past its rating it will eventually catch fire, but not because of physical pressure. Good batteries, and good chargers, are carefully designed to prevent overcharging.

On December 16, 2015 at 2:46pm
Craig Blair wrote:

Is there any way to be forewarned of a Lithium- ion battery’s eminent failure? Is temperature an effective way to predict it, or is it ONLY a matter of metal particles causing a short? IF temperature provides an effective warning, at what temp should one cease operation?

On January 2, 2016 at 9:00am
Deb Freed wrote:

my son has a hoverboard and I know there have been issues with them beating into flames.  How can I safely store the hoverboard so that a fire would be contained if it combusts while no one is home?  Would it be safest in the bathtub? Wrapped in a fire safety blanket? Placed in a fire safe (seems like an expensive solution)? Or do I just spend my life in a panic that my house will burn down when I’m not home?

On January 2, 2016 at 12:09pm
Roger Bohn wrote:

1. Most important, only charge it when someone is home and in the same room. Most fires occur when charging. If possible, charge outdoors. Also for some period after charging.

2. Store: on a concrete floor with nothing around (garage). Bathtub is ok but not very practical. Fire blanket is good.

3. When in any crash (which is probably common) - treat it as likely to go off for the next few hours. If the battery OR circuitry were damaged, such as a short circuit, a fire is more likely.  Good luck!

On January 2, 2016 at 2:28pm
Deb Freed wrote:

My brother suggests draining the battery (running the hoverboard until the battery is dead) and then storing it that way.  Would that eliminate the risk of spontaneous combusyion?  If so, that is a simple solution.  My son can just charge the hoverboard the next time he wants to use it (he will be away for several weeks).

On January 2, 2016 at 2:48pm
Roger Bohn wrote:

Yes it will reduce risk of combustion, but no, you do not want to do that. Draining a lithium ion battery reduces its life considerably. In extreme cases, you can ruin the battery.

He does have a very good point thought that you should store it at an intermediate charge level. Do not store fully charged, because that somewhat increases the risks as well as increasing the size of a fire if one occurs.

By the way, is there a better discussion board for discussing these boards specifically?

On January 4, 2016 at 12:06am
Dave Potter wrote:

The hoverboards and laptops are getting a lot of attention, what about the 18650 batteries used in flashlights and other small devices?

On January 4, 2016 at 12:15am
Roger Bohn wrote:

Good question. I have not heard of problems with 18650s, but on the other hand I refuse to buy the cheap ones because I expect that they have the same sorts of safety hazards.

I know there are some reputable companies - I think Panasonic is the main one. Panasonic makes the energy storage core; other companies then add the electronics. So a Panasonic core + cheap electronics is sti≥ll dangerous.

Maybe someone can research and provide URls .

On January 4, 2016 at 12:20am
Roger Bohn wrote:

I have written a short blog post on hoverboard battery safety. Visit Art2science.org
Comments and questions there are welcome

On January 4, 2016 at 10:03am
Ron Butler wrote:

As the “building block cell”,18650’s certainly possess a failure potential. Most of the available burn tests have been done using these cells.

On January 12, 2016 at 3:48am
Andy Lea wrote:

I have 4 cells in a waterproof case. Do I need to remove the cells to charge? The box is probably air tight. Do the cells need to vent gas?

On January 18, 2016 at 4:43am
paul dennison wrote:

On Saturday evening a 3000mA/h brand name Efest exploded in my e-cig in my hand. The room filled with thick smoke and several small fires were caused as the device took off like a rocket I was able deal with these.Clearly I breathed the smoke in, but the room and I were covered with black dust.  Is there any medical advise on what I should do now please?
Is there any legal advise?


On January 18, 2016 at 2:30pm
Roger Bohn wrote:

Smoke inhalation is potentially serious, but seek real advice. I got a small whiff once, and it aggravated my asthma for a day.

Can you say more about circumstances? Were you using it at the time? Charging it?

I also wonder why such a large battery was in the product. But I know nothing about e-cigs. 
Thanks for reporting this - I hope you will post this incident more widely e.g. on e-cig sites.

On January 19, 2016 at 12:52am
Bob Seaver wrote:

I have a cell stuck in my Nikon D5000.  If I sdrill a hole in it to gewt it out, is that dangerous?

On January 19, 2016 at 1:06am
Bob Seaver wrote:

The cell is identified by a label that says it is a li-ion cell.  It is tha standad battery thati is used ro power Nikon D5000s but not a Nikon product; so it resisted being inserted and is struck by friction in the camera body.  Sorry to be so vague, but this is new for me.

On January 19, 2016 at 2:55am
paul dennison wrote:

The e-cig WAS a “Nemesis” made of stainless steel approx 106 mm by 22 mm dia.
I was changing the discharged battery with one from charger designed for these batteries.
It exploded as I hand tightened the parts together. Later that day I experienced severe stomach pains,and on advice from NHS direct then from my GP I visited A&E.  I was given two blood tests My only symptoms were stomach pain and small burn on my leg.They found a minor infection in my kidneys and provided antibiotics for this, conclusion the pain and e-cig were unrelated. I took photos of the carnage which a can email if required,please provide an emaill address. Thanks

On January 19, 2016 at 9:42am
RB wrote:

Don’t do it!  Sticking metal into a charged battery is guaranteed to short circuit and cause a fire. 99%. At best it would destroy the camera. At worst, burn your hands and start a bigger fire.
  How about finding a site of Nikon camera people and asking them?

On January 19, 2016 at 11:47am
Roger Bohn wrote:

To Bob: To strengthen my message: NO!!!!! It’s really going to make a mess and perhaps start a fire. And destroy the camera. And burn your hands if you don’t drop it fast enough.
If for some reason you decide to do it anyway, please do it outside and not near any flammable material.

Physical damage to a lithium battery is the second big cause of fires (along with overcharging). In radio controlled flying, when a plane does a nose-dive, we treat the battery as “about to catch fire.”
  Good luck. I bet there is another way to get that battery out.

On January 23, 2016 at 7:34am
barbara cissell wrote:

Do you recommend charging a laptop ion battery to only 90% to prevent overcharging and exploding.I have heard this is a good number.Also,how low should I let it get down to before I plug it back in? Is 2% a good number? Thank you.Confused in Louisville Ky

On January 25, 2016 at 1:38am
Roger Bohn wrote:

Barbara, don’t worry about laptop batteries, assuming the laptop is made by a first or second tier brand name. They are MUCH safer, with electronics to protect against overcharging, over-discharging, etc.
Laptop batteries cannot be overcharged because of protection in both the battery and the charger. You will slightly reduce the life if you let them be fully discharged frequently, but they are intended to give a full charge from 100 down to 0.

Why the safety difference? Brand name: Cases of laptop fires get lots of attention. Also certification by UL laboratories. Also government regulation: the CPSC would get involved if there were persistent problems. Also tort law: fires would lead to lawsuits.

Fires of the hoverboards will lead to lawsuits, but I expect that the companies that made them will be hard to locate, and then will turn out to have no assets if someone wins a suit. Tort lawyers have a bad reputation, but this is an example of why they can be good for safety!

On February 8, 2016 at 4:06pm
Verena Jolly wrote:

Hi, I’ve bought a GPS tracker with a Li-ion battery that I wanted to use on my horse.  Having read the info here…it sounds like there’s a risk of it setting on fire/exploding and injuring/killing her, especially as it could be subjected to some forces if she were to squash it when lying down to sleep etc.  Can anyone confirm please if I’ve correctly understood the risks?  GPS trackers are commonly used on pets and they presumably have lithium ion batteries…so are they risky too?

On February 12, 2016 at 1:43am
subrata das wrote:

Drones, mobile phones, laptops, mobile appliances use LITHIUM batteries. Avoid using chargers that implement fast charging overnight. Avoid power extension sockets near sofa, living room carpet. CHARGERS should be kept in well-ventilated area.
Mr Ian Johnson, 74 technical expert, attended a course in Germany on operating drones, left three drone LITHIUM polymer batteries to charge on the carpet floor besides sofa. At 3am in just 2 hours 4-generation family house reduced to a charred state at Parry Avenue Singapore, June 9, 2015. He died of extensive burns in the corridor.