How safe is Lithium Cobalt compared to Lithium Polymer?

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How safe are Lithium Cobalt batteries compared to Lithium Polymer?
I have read much about LiPo being not that safe and there are more than 100 movies on youtube about exploding LiPo's but not much is known about the safety of LiCo (Lithium Cobalt) while it is being used in almost everything.

I finally have certainty about the batteries in my new bike which is going to be delivered.
It's name is Li-ion and I found out it is a LiCo, Lithium Cobalt some say it has a poor performance for e-bikes. Panasonic Li-ion CGR18650CG.

This bike has to be placed in my little corridor.
There are so many tests on youtube with exploding batteries but never do they test real e-bike battery boxes which are on the back of your bike.
How strong is such a standard factory case for a 36 volt battery pack, has anyone on this earth ever tested that?

46276550.jpg
 
lithium polymer is a format..
lithium cobalt is a chemistry..

The exploding batteries you see are lithium cobalt batteries, in polymer format ( pouch ). The same safety issues occur when they are in cylindrical format.

But different formulations of lithium cobalt cells, whether cylindrical, prismatic, or polymer/pouch have varying levels of safety.

Remember all the exploding laptops and gadgets from the mid 2000's? all lithium cobalt.. and a lot of the explosions were from cylindrical cells.

So if you want improved safety, those panasonics may not be the way to go. I cannot find any information about safety tests on the 'net for those. Assuming that they are a high power lithium cobalt cell, i'd assume they are vulnerable to the same thing that the RC Lipo packs are.

( didn't we have this discussion like a week ago? )
 
No no. it's more than that. You can abuse a lifepo4 pretty damn hard and reasonably expect it to just die and no longer work.

Go try the same thing with a hobbyking pack.

There is always the teeny, tiny possibility of a dud cell.
Even in the best managed pack ( you have a BMS designed by the gods, never let it overdischarge, and run it well within it's specs or under ) can experience a failure due to a dud cell. The failure mechanism varies from chemistry and brand to 'silently dies in the night and won't accept a charge again' to 'sweet! the next door neighbor is having a death metal show inside the house!'


Why do you think nobody has lifepo4 fires? but some RC Lipo packs and even laptop/gadget cells being lithium cobalt have just exploded out of nowhere, despite having a BMS, even a properly designed one?
 
Not true. Lifepo4 can be abused too. Safety for all battery types revolves around a good bms and cell management.
 
It can be abused, but it will not explode in flames or fill a house full of toxic smoke.
It is by far one of the most safest formulations available.
I've literally never heard of a lifepo4 smoke or fire event - have you?

Luke ( liveforphysics ) who tested every type of cell he could get his hands on a few years back.

[youtube]dree0rTr1HM[/youtube]

Lithium batteries vary in safety very widely.
There are even some li-co cells he tested, in cylindrical format, and in pouch format ( lipo ).. which would not catch fire or shoot smoke.

The ultimate answer is that you do not know until you've seen tests.

Some chemistries are generally safer than others.
 
LiFePO4 fires also occur. Don't assume it is inherently safe. It can explode into a fireball. The smoke from LiFePO4 burning is not something you want to breathe. I wouldn't tell people it can't burn. It is full of flammable material and lots of energy. There are plenty of cases of LiFePO4 fires documented if you look for them.
 
I can find about 3 instances. Whereas you can hop on a RC forum where people are using the more dangerous forms of li-co and find hundreds of instances of fire. You can go on youtube and search lipo fire and come up on probably a hundred videos.

Let's be realistic. What has the best track record? lifepo4 or formulations involving lithium cobalt? I did not know a lifepo4 fire had ever occurred until you mentioned it, and i've read this board daily for around 2 years. lithium cobalt batteries have a long and storied history of going kaboom. ipods, macbooks, dell laptops, sony laptops, and many other very common consumer devices have had rashes of unpredictable battery fires in the past, mostly in the mid 2000's, but they are still happening today. The industry is slowly moving towards NMC/NCM, which is definitely safer.

If you are looking for the safest chemistry, lithium cobalt is probably not the first place you want to look.

The chances of a lithium cobalt battery fire are very minute with modern formulations, however.. but any level of risk is unacceptable to some.
 
neptronix said:
It can be abused, but it will not explode in flames or fill a house full of toxic smoke.
It is by far one of the most safest formulations available.
I've literally never heard of a lifepo4 smoke or fire event - have you?
Click to expand...
While LiFePO4 cells can take a lot of abuse compared to some other Li chemistries, I've personally "jellyrolled" several A123 M1 cells. It makes a LOT of incredibly toxic smoke and the cell burns very hot, easily melting anything nearby. No jets of flames, but quite dramatic.
 
Wasn't one of Lyen's packs that caught fire on his bike a LiFePO4?
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=18577

Long time back, I've seen videos linked on DIY Electric Car forum of various large prismatic LiFePO4 smoking and burning in abuse tests, though I don't recall any actually exploding. If they were in cylindrical format, I think that they would indeed be able to explode if their vents failed (same problem that probably causes LiCo and similar to do that; it's what happens with NiMH and NiCd when they pop).
 
My poor memory comes up with just one lifepo4 fire. A dead short caused by a sharp edge on sheet metal cutting into the pack. The duct tape lifepo4 pack similar to an early ping but from another vendor then burned the converted vesapa vehicle. The pack was just sitting in a spot where it could rub on a sharp metal edge inside the scooters body metal.

So it can happen, and it's why to this day i shudder at the thought of pouch lithium of any chemistry taped all over the frame, or just stuck in a bag. Foam is not enough protection, you should build a simple hardshell box for your pouch cell battery. Coroplast, the top to a large storage tote, and a cookie sheet are methods I've used.

I have no recolection whatsoever of a lifepo4 battery in use on a vehicle self combusting just because it got charged or discharged incorrectly though. That can happen with RC lipo like we are putting on our high performance bikes.

I have inadvertently had paralell connections disconnect while riding with RC lipo. The resulting discharge to 0v of the remaining connected pack resulted in puffing, release of toxic flamable gasses, and enough heat to melt and discolor the heat shrink, till the shrink tube failed and let the pack puff like crazy. Too hot to handle bare handed for sure. But happily, for me no fire. I've done it twice. What a moron letting it happen the second time! :roll:

So there definitely is a risk, even while just riding along with RC lipo, if you make a mistake. Some tape on the connections would have easily prevented that disconnected pack, so not a difficult hazard to avoid. All paralell connections on my bikes are now made more frockup proof.
 
Any charged lithium cell contains energy to produce intense heat.

I generally consider LiCo vs. LiFe like Gasoline vs. Diesel... they both burn, but LiFe (like diesel) is a bit less dramatic.

IIRC, completely discharged LiCo can sustain flame, I'm not sure completely discharged LiFe can.
 
neptronix said:
lithium polymer is a format..
lithium cobalt is a chemistry..

The exploding batteries you see are lithium cobalt batteries, in polymer format ( pouch ). The same safety issues occur when they are in cylindrical format.

But different formulations of lithium cobalt cells, whether cylindrical, prismatic, or polymer/pouch have varying levels of safety.

Remember all the exploding laptops and gadgets from the mid 2000's? all lithium cobalt.. and a lot of the explosions were from cylindrical cells.

So if you want improved safety, those panasonics may not be the way to go. I cannot find any information about safety tests on the 'net for those. Assuming that they are a high power lithium cobalt cell, i'd assume they are vulnerable to the same thing that the RC Lipo packs are.
Click to expand...

I am not convinced that Lithium Cobalt and Lithium Polymer are the same.

Wikipedia about LiPo:
This type has technologically evolved from lithium-ion batteries. The primary difference is that the lithium-salt electrolyte is not held in an organic solvent but in a solid polymer composite such as polyethy- lene oxide or polyacrylonitrile. The advantages of Li-ion polymer over the lithium-ion design include potentially lower cost of manufacture, adaptability to a wide variety of packaging shapes, reliability, and ruggedness.


Also look at: Lithium Polymer Vs. Ion Battery eHow.com
http://www.ehow.com/about_5545273_lithium-polymer-vs-ion-battery.html
 
Oh, well if wikipedia says.... :lol:
 
dogman said:
Oh, well if wikipedia says.... :lol:
Click to expand...

:eek:
Yes I noticed they are not always up to date, but other sites?
Also look at: Lithium Polymer Vs. Ion Battery eHow.com
http://www.ehow.com/about_5545273_lithi ... ttery.html
 
Lithium Ion is a class name. Batteries are kind of like food recipes, there are many variations on the theme. Lithium Ion Cobalt Oxide is a more specific chemistry, the most common in the past. Most Lipo is Lithium Ion Cobalt Oxide in Polymer, but there is also Lithium Ion Iron Phosphate in Polymer. Laptop cells are Lithium Ion Cobalt Oxide in tubular form. There is also Lithium Manganese Dioxide in many tool batteries, and the new Lithium Ion Nickel Manganese Cobalt Polymer that the Volt and Zero Motorcycle are using. However manufacturers can tweak these chemistries to change their characteristics a bit regarding how stable they are and how safe they are. Traces of the wrong chemicals can make them bombs, or the right seasoning make them extra stable. All of the Lithium Ion chemistries cannot use water as a component in their electrolyte, so they use flammable solvents, and other components inside are usually flammable. The sources you are quoting are pretty shallow in their coverage, detail level and precision, and much of it is proprietary to the manufacturers in the details, so they are intentionally vague.

Over time the manufacturers improve their recipes, so old style Lipo would burst into flame overcharged to 4.3 volts, some good newer stuff doesn't do that at all, and will handle 5 or 6 volts, and new companies spring up making cells using old recipes. So you can't easily tell.

Panasonic is a good manufacturer, their stuff is likely using good stable chemistry. Sony also, but some batches of Sony batteries burned a lot of laptops, so even a good company can have a bad day.

Besides the chemistry the charging and discharging system has a lot to do with safety. It is the whole system that determines how safe they are, and then how you treat them has an effect also.
 
I like Tyler's analogy for simplicity.
TD wrote: I generally consider LiCo vs. LiFe like Gasoline vs. Diesel... they both burn, but LiFe (like diesel) is a bit less dramatic.
Click to expand...

Cautious use, well designed BMS and charging procedures and protected casings (like dogman mentioned). I like the Pelican cases because they are strong, easily removed (but not too easy for strangers) and they look and function like the panniers I had on my BMW. Marine Supply has a nice selection of sizes.
 
So there is a difference.
But let's take a high quality Lithium Ion Cobalt Oxide and compare that to a high quality Lithium Ion Cobalt Oxide in Polymer.

Which of the two are safer, is there a significant difference?
 
The difference is, one is rolled up and stuffed in a stainless steel can that can develop some pressure before bursting and sending shrapnel everywhere.

The foil pouch can't hold more than 0.2psi before its seems split open and it vents.
 
dogman said:
Oh, well if wikipedia says.... :lol:
Click to expand...

It is actually the articles on lithium batteries that shaked my faith in wikipedia's accuracy, after taking it as 'the word' for many years :lol: . They are truly awful, innacurate, and need to be rewritten from the ground up.

There is plenty misinformation elsewhere too.

I already argue with people on battery tech here enough, i don't have the energy to fight a tide of stupids on wikipedia :|
 
liveforphysics said:
The difference is, one is rolled up and stuffed in a stainless steel can that can develop some pressure before bursting and sending shrapnel everywhere.

The foil pouch can't hold more than 0.2psi before its seems split open and it vents.
Click to expand...

My conclusion is that they are both just as safe or unsafe.
I wonder why Sachs has put in the Lithium Cobalt batteries in the latest models. They are probably cheaper but have more weight.
 
Alan B said:
You are right about weight. Tubular cells are heavier both due to their packaging materials and their greater electrolyte volume.

You can't really know about the safety. They both have risks and are almost certainly not equal, nor are they either totally safe.
Click to expand...

What do you think?
Which of the two are safer, and is it a significant difference?
 
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