# Lithium Ion Categories



## LuxLuthor (Jul 27, 2008)

_*After many questions and confusion over various Lithium Ion battery types discussed in this 18650 thread, I thought it would be useful to try and give a breakdown of the various categories of Lithium Ions. There are more details that could be given, but this is meant to just be a "handy" guide.**

Edit: I recently did a "Safe Chemistry" 18650 Shootout here

Source References:*_

*1)* This Battery University page gives an up to date feature/functional performance Lithium Ion comparison.


*2)* This M-Power page is a good summary of Li-Ion battery concepts.
*
Three structural parts inside the battery can & top:
*

*1)* When we talk about various Lithium chemistry batteries, most of the differences relate to the structure & metal alloy used in the *positive cathode*.


*2) *Since 1996, the *negative anode *made of graphite (carbon) has been well optimized.


*3)* The *electrolyte *is a Lithium salt solution, and may be a source of further improvements in the future.
*
 Two major categories of Lithium batteries:
*

*1) Lithium Primary* (non-rechargeable) batteries which contain pure Lithium metal which is volatile in water/oxygen.


*2) Lithium Secondary* (Li-Ion or LiPo -rechargeable) batteries which contain Lithium as an cathode alloy or salt. They have no memory or self-discharge issues.
* Four major categories of Secondary Li-Ion cell cathode metals*:



*a)* *"Unsafe" Lithium Cobalt Oxide (Layered Structure) *is the original Lithium Ion rechargeable cell, first made by Sony in 1991. It is what most people recognize as Li-Ion, and is now made by many companies such as *Sony, Sanyo, Pila, Panasonic, AW *_(sales link)_*, *etc. 

Lithium Cobalt is a more volatile cathode material with a higher resistance to the flow of ions, resulting in heat buildup. _*

It is best to use cells with separate built in protection circuit (AW & Pila), or pack with circuit board ("PCB") & balance tap leads going to each cell (or at least to groups of cells). This protection PCB resolves most of the safety concerns & issues.
*_
​

*Limited charge/discharge loads* without heating up (fire/explosion) are generally *1-2C* (5 Amp discharge & 2 Amp charge in protected 18650 cell)


Higher stored capacity. 18650 size has ~*2200mAh*


Higher *3.6/3.7V* nominal voltage, charges up to *4.2V*


Begins losing function (voltage drops) in 2-3 years after manufacture due to Lithium crystalizing onto Lithium Cobalt Oxide cathode layers, thereby increasing internal cell resistance.


_*Useful rule of thumb for checking the voltage to determine charge capacity left in a Li-Cobalt cell.*_

_These readings should be taken where cell has rested at least 15 mins after charge, not under any load._
*4.2V Full 100%
4.1V About 90%
4.0V About 80%
3.9V About 60%
3.8V About 40%
3.7V About 20%*
*3.6V Empty 
<3.5V Overdischarged
<3.0V Cell damage* *occurs *_(increasingly based on duration and how much lower voltage goes.)_
​

*b) "Safe" Lithium Manganese (Spinel Structure)* developed in 1996, with increased cathode surface area using a complex 3-dimensional cross-lattice "spinel" structure. Only made by: *Emoli.*_ Found in specific *Ridgid *or "*Ryobi One+ Lithium*" tool packs._


Has *much higher discharge rate of 10-15C* (for 18650 cells that's 15-20 Amps output). It should be *charged at 1-2C* (1.5 to 3.0 Amps).


Moderate stored capacity. 18650 size has ~*1300mAh*


Higher *3.7/3.8V* nominal, charging up to *4.2V*


Begins losing function (voltage drops) several years after manufacture due to Lithium crystalizing onto Lithium Manganese Oxide cathode.
.

*c) "Safe" Lithium Nickel Cobalt Manganese *cathode. This is close to the previous category, but this combination gives a bit more capacity but a bit less output rate. This is the *Sony V* (or *VT *in 26700 size), *Sanyo*, or *Konion *is another licensed brand made in Germany. _Found in specific *Makita, Ryobi, Bosch *tool packs._


Has *higher discharge rate of 5-7C *(for 18650 cells that's ~10 Amps output). It should be *charged at 1-2C* (1.6 to 3.0 Amps).


Moderate high stored capacity. 18650 size has ~*1400mAh*


Higher *3.7V* nominal, charging up to *4.1V *(charging higher reduces cycle life from 800 to 300 cycles)



Begins losing function (voltage drops) several years after manufacture due to Lithium crystalizing onto Lithium Nickel Cobalt Manganese Oxide cathode.
.

*d) "Safe" Lithium Iron Phosphate *cathode. This has a huge leap forward in discharge rates, but with a lower capacity & voltage. _It needs a separate charging setup. _*Saphion *is one of the original brands, with other Chinese/Hong Kong versions springing up (including some from CPF member: AW). There is a "Nano" Lithium Iron Phospate made by the *A123 Systems* company which seems to have the highest quality and performance.


Has *very high discharge rate of 25-35C *(for 18650 cells that's ~*30 Amps output*). Can be *charged at 2-5C* (2 to 6.0 Amps). Able to take significant user abuse.



Moderate stored capacity. 18650 size has ~*1100mAh*


Lower *3.3V *nominal, charging up to *3.6V*.



Has longest life & number of cycles, but will still fail in several years. _(I don't have exact handle on this.)_


----------



## LuxLuthor (Jul 27, 2008)

I'll call this post: "LuxLuthor Tips"

While there is leeway with the 3 (current) brands of *safe *Lithium Ion chemistry batteries regarding charging, it is still wise to check voltages of individual cells of a pack charge setup (i.e. like from FiveMega or Modamag). This should be done periodically _(? every 5-10 charges or more often if imbalances are noted)_ to make sure they are all getting fully charged and discharged together.

While the protection PCB circuit in "unsafe" Lithium Cobalt chemistry cells does resolve much of the concern of *overcharge *safety, and *overdischarge *cell damage, it will not balance cells.

If I were to make Lithium Ion cells into a pack (which I have done), I would always install individual cell "balance tap leads" so there is a way to keep cell voltages balanced.

It is best to not over-discharge any of the Li-Ion cells. A general guideline for the first three to give best lifespan is not discharge lower than 3.3 Volts. You can go lower....even down to 2.8V briefly, but it will do progressively more damage once you go below. With A123 type LiFePO4, it has a very flat discharge curve at 3.3V, and then suddenly craps out, so stop using immediately. 

Best rule of thumb is to learn how your cells behave....so stop using a light when you notice light dimming (or cutting off if it has a PCB), and check your voltages to see where cells dropped to.


----------



## Patriot (Jul 27, 2008)

Nicely laid out! I'll probably have to read it a couple of more times to retain the finer points but this is very helpful.


EDIT:

It looks like the Lithium Nickel might be the best compromise between capacity and discharge rate for most flashlight purposes.

Thanks Lux :thanks:


----------



## LuxLuthor (Jul 27, 2008)

Patriot, I don't think the slight difference in capacity between Emoli & Konion/Sony-V is that significant as compared to the discharge rate Emoli advantage. I think it more comes down to the pack price.

The A123 cells in 18650 size as far as I know are only in the Black & Decker VPX packs, which I think is being phased out. Only reason I would consider those in this size was if I needed a lower voltage setup. It is extremely rare for our flashlights to need the higher A123 Amp output than Emoli or Konion delivers.


----------



## DM51 (Jul 27, 2008)

Lux - excellent! I've added it to the "Threads of Interest" sticky.


----------



## Patriot (Jul 27, 2008)

LuxLuthor said:


> Patriot, I don't think the slight difference in capacity between Emoli & Konion/Sony-V is that significant as compared to the discharge rate Emoli advantage. I think it more comes down to the pack price.




I see what you mean. For some reason my brain saw that as 2600mah instead of 1600mah. I completely agree then that the Emoli has a big advantage.

Speaking of 2600mah, doesn't LG and a couple other manufacturers now make 2600mah lithium cobalt batteries? It still seems like the these would make a lot of sense for LED applications, since capacity is important and discharge rate not as important.


----------



## LuxLuthor (Jul 27, 2008)

Thanks DM! 

Patriot, yeah there are wide variations in Li-Cobalt capacities. But then there are capacity claims and real capacity. Likewise you should be selective with the quality and protection cup of protection circuits. I would have a hard time not choosing AW or Pila.


----------



## Holzleim (Jul 27, 2008)

I'm not sure if the so called LiPo (Lithium-Ion Polymer) cells belong to one of the categorires you mentioned.
These cells provide very high dischahrge rates (20-30C) and I think energy density is good as well. They are very commonly used in RC-Cars, Helicoters, ...
Wiki: http://en.wikipedia.org/wiki/Lithium-ion_polymer_battery

I used them in two in of my lights and am quite satisfied with results. If you look at my small 4W light, I'm really impressed of these small cells being able to supply 2A.

I integrated charging electronics, so all you need to refill the lamp is a 5V mini-USB plug.

Certainly are these cell not that suited for modding lights that have round dimesions optimized for standard sized cells like many here do, because the cells usually have rectangular dimesions.


----------



## jayflash (Jul 27, 2008)

Lux, thanks much for the concise and complete listing of the various LiIon cell specifics. Very useful information!


----------



## LuxLuthor (Jul 27, 2008)

Yeah, I was mainly looking at the variety of chemistries available in 18650 size cells where there is the real diversity of chemistry types--and which gets confusing. LiPo are closest (but much less safe) to the Lithium Cobalt Ion cells.


----------



## rdh226 (Jul 27, 2008)

Hey Lux, have you heard anything on the lithium nano titanate batteries?

I haven't been able to find all that much online, viz:

http://www.newscientist.com/article.ns?id=dn7081
http://www.nextenergynews.com/news08/next-energy-news7.9.08c.html
http://www.b2i.us/profiles/investor/fullpage.asp?f=1&BzID=546&to=cp&Nav=0&LangID=1&s=236&ID=9313

(A 2MWt battery pack? Woof!)

I recall reading somewhere they're 2.3V cells rather than 3.3/3.6/3.7V, and with a little less energy
density than LiIon, but "Safe" (Type "5" in your list?), and with _thousands_ of charge/discharge
cyles over a decade of life.

I first heard of them via the new (http://www.lightningcarcompany.co.uk/home.php) English Lightning 
sports car, and the (http://www.phoenixmotorcars.com/) Phoenix fleet SUVs.

-RDH


----------



## LuxLuthor (Jul 27, 2008)

RDH, only thing I have heard on that company/technology is their focus on large utility power supply backup storage that you mentioned. Getting from a new technology like that--scaled down to a power tool size when A123, Saphion, Emoli, Sony/Konion already have a foothold will likely present a real challenge. That is why I suspect these various new Lithium battery technologies are targeting various niche uses like Power Plant backup/storage, electric cars, power tools.

This Forbes story is linked on their home site, and gives a good idea of the complexity facing Altair Nanotechnologies in this pursuit. It is interesting that they are looking at the previously "settled" performance of the graphite anion to get the fast charge capability. Hope it works out they way they intend.


----------



## SR.GRINGO (Jul 27, 2008)

Lets say you are building an elephant with 8 cells. Would you use the emoli or the AW 18650?

I see the advantage of AW being plug and play.


----------



## Raoul_Duke (Jul 27, 2008)

SR.GRINGO said:


> Lets say you are building an elephant with 8 cells. Would you use the emoli or the AW 18650?
> 
> I see the advantage of AW being plug and play.



Series or parallel?

As FM holders for the Elle-2 are series, I assume thats what you mean.

I guess that if you are using a ~4A lamp the AW may be better suited, as they have larger cappacity, and will shut down when the V becomes to low; If you need more current, like 12A for the Osram 64657 then then Emoli would be the only way to go.


----------



## LuxLuthor (Jul 28, 2008)

Yeah, as Raoul says, the 5 Amp protection circuit limit of AW (or any Li-Cobalt) cell is the determining issue for a given bulb....and if you are using 8s x 4.15V (33V), by definition you are using a high current bulb. Almost any bulb above 50W is going to need over 5A current.


----------



## SR.GRINGO (Jul 28, 2008)

Raoul/Lux,

Thanks for clearing this up....starting to get a grasp on this. Can the Emoli's that are harvested out of the rigid pack fit into FM's battery holder for the elleII? If not, Lux will you make an emoli pack?


----------



## jeffosborne (Jul 28, 2008)

Well done, Lux Luther, one I will save & keep this documentation.

But you mentioned "balance tap leads",, which I have wanted to include on the battery packs I have assembled, but I have always tripped over one point: How do you protect that connector? PTC or fuse for each line? Perhaps I am too paranoid. I used Battery Junction's 3-cell protection PCB's for my packs, and that seems fine. But bringing those leads to a connector on the side of my battery enclosures seems like a asking for trouble. A simple short circuit and "poof!" The leads circumvent the protection PCB, right? How do you deal with that, Lux?

Thanks a bunch,
Jeff O.


----------



## LuxLuthor (Jul 28, 2008)

When I make a pack, I weld a Nickel contact strip to the batteries. The balance tap wire is first soldered to the middle of the contact strip. Tap wires need to run down either in the center space of 4 cells, or along length in gap outside two cell bodies. Ultimately I have them come down together into a shrink pigtail, and then into a JST balance connector. You need a heavier guage wire/contact end plate like shown in my battery pack signature link for the major charging current. I have enough safeguards that I am not concerned about needing a fuse.

When I make a pack, it is all cushioned with mastick and shrink wrapped to insulate. It is not as easy to set up a safe scenario with an FM battery holder, although I did make one.


----------



## sylathnie (Jul 28, 2008)

Excellent post Lux. Thanks!

My intention for balance charging my cells was to assemble a separate "charging tray" with slots for each cell. This will allow me to permanently wire the balancer into it as well as making it easy to swap out bad cells. I do loose the advantage of pack charging and balancing but I don't think I will balancing more than once every 3 or 4 charges. (Maybe longer if they don't get out of whack to quickly.) 
I'm also toying with the idea of adapting it to different cell sizes but I haven't decided on a good batter retention method.


----------



## TorchBoy (Jul 28, 2008)

LuxLuthor said:


> LiPo are closest (but *much less safe*) to the Lithium Cobalt Ion cells.


Nice resource. 18650s aside for a moment, I remember when lithium ion polymer took over from lithium ion in cellphones. So they're the same chemistry but with different construction? What do you make of the claim in the Wikipedia article "The advantages of Li-poly over the lithium-ion design include lower cost manufacturing and being *more robust* to physical damage"?


----------



## LuxLuthor (Jul 29, 2008)

TorchBoy said:


> Nice resource. 18650s aside for a moment, I remember when lithium ion polymer took over from lithium ion in cellphones. So they're the same chemistry but with different construction? What do you make of the claim in the Wikipedia article "The advantages of Li-poly over the lithium-ion design include lower cost manufacturing and being *more robust* to physical damage"?



The construction differences are huge. The liquid electrolyte in Li-Ion is polymerized which in theory eliminated the need for a metal battery can with LiPo's. Battery University has another page on the differences here. They discuss the gel changes from original dry polymer design as a way to improve conductivity. Assessing cost is a complex set of changing variables.

The problem with Wiki has always been the unknown quality of comments that anyone can make. I never take anything important as accurate in Wiki unless I have correlated it with other authoritative sources. 

Sometimes Wiki is spot on, other times not...and you never know for sure which applies to your inquiry on that particular day. There is also the theory about Lithium Ion & LiPo design vs. real world reality (see post #4). Show me a similar list of tragedies for Li-Ions. 

How much of these LiPo disasters are related to cheap/poor quality manufacturing, &/or higher volume use by more aggressive/reckless RC users, &/or involving crashes of planes & cars, &/or abusing charging regimens to get their plane back in the air....who knows how to assess all the factors?

Again, this thread is mainly about Li-Ion cells that can be used in our flashlights, and trying to organize what is available with the newer safe lithium chemistries.


----------



## TorchBoy (Jul 29, 2008)

LuxLuthor said:


> There is also the theory about Lithium Ion & LiPo design vs. real world reality (see post #4).


 Wow. And most of them are from charging errors. I see that even if they are "more robust" it's really a relative term. When I take the plunge I'm definitely going for one of the safer varieties you list.


----------



## Anders (Jul 29, 2008)

Thankyou LuxLuthor.

Good info.



Anders


----------



## LuxLuthor (Aug 23, 2008)

This topic is linked in the top pinned "Threads of Interest," so you can find it. I also added a link in the first post for the recent shootout of safe Lithium chemistry 18650 cells.


----------



## gunga (Dec 5, 2008)

Wow, just found this thread. Excellent info.

ALso nice now that AW has LiMn (IMR) cells. 18650 has a claimed capacity of 1500 mAh.

Is this likely to be correct?


----------



## LuxLuthor (Dec 5, 2008)

Gunga, thanks for feedback.

AW has provided reliable stats on his cells previously, so I expect he has carefully verified the performance. He posted some run charts in my shootout thread of safe 18650 cells here  (for future reference that thread is listed in the pinned "Threads of Interest" at top of this section). He claimed his were closest to the Sony "V" model which I display.

I just ordered 6 from him, and will test the crap out of them, and add performance graphs to the existing ones.


----------



## uk_caver (Dec 11, 2008)

As part of a discussion elsewhere on powering a Serv-Light (which requires 3.6-4.5V, and I'm guessing uses linear regulation, and no inbuilt low-voltage cutoff), someone suggested that they were going to use a 3x parallel lithium pack:
http://www.all-battery.com/li-ion1865037v6600mahrechargeablebatterymodulewithpcbfreeshipping.aspx
The issue came up of cutoff voltages, and whether or not the light would just stop working in normal use, so I looked at the specs and saw the low voltage cutoff was at 2.4V, which was lower than I expected. Even though at battery university http://batteryuniversity.com/partone-5B.htm
it does mention cutoffs being 'around 2.5V', I'd got the impression that a cell was basically empty at 3.0V.

In practice I guess that once the battery voltage drops below ~3V it's likely that people will be swapping battery packs, so voltage would rarely get down to 2.4V unless a light is accidentally left on.

However, if a pack is occasionally run to the cutoff, is it even a _potential _safety issue, or just a battery-life issue?

Also, if a 6.6Ah pack is run much below 3.0V, would it be safe for someone to use a 3.0A li-ion charger on it, or should it be charged more gently until the voltage recovers?


----------



## LuxLuthor (Dec 11, 2008)

Most of the protection PCB's either for individual cells (like AW & Pila), or pack PCB's have this low voltage shutoff protection at around 2.4 to 2.6V, and when it rebounds back up to 2.9 to 3.1V, the PCB shutoff resets. 

I wish it was set a bit higher, but *in theory* for decent Amp drawing applications such as most incans (> 1 to 2 Amps), the exhausted spike down will happen very sharply & quickly (see my linked safe lithium testing discharge graphs above), so very little time is spent in the battery damaging low voltage range. 

Where you run into more problems are the direct drive LED lower current applications which keep drawing the life out of the battery at a slower drop rate before reaching the low voltage shutoff level. The longer the cell spends below 3.0V, the more it is damaged. 

I don't see this as a safety issue, however. Certainly most all the issues with Li-Ions are with *charging too high*. 

I have read in various charger manuals & other locations that a more gentle charge should be used for really low levels before applying a 0.5C charge rate such as your 3A charge rate example for a 6Ah pack.


----------



## uk_caver (Dec 11, 2008)

Thanks for that.

I was just concerned that after having responded to a thread elsewhere on the question of whether the cutout would be likely to leave them suddenly in darkness, I should check out the implications for the battery pack.


----------



## Vikas Sontakke (Aug 13, 2009)

Can somebody tell me out the following 3 categories, where do typical 18650 cells fit?

Lilo (I think that is typo, unfortunately it is all over the internet; lower case "L" and upper case "I" look very similar, so I suspect the original auther intended it to be LiIo and after few re-writes, it become Lilo)

LiPo (are these the one in typical R/C helicopter?)

LiFe (Are these the low voltage rechargeable Lithium?)

I just ordered a fancy charger which needs to be told the type of Lithium rechargeable being charged.

Thanks,
- Vikas


----------



## LuxLuthor (Aug 13, 2009)

Vikas Sontakke said:


> Can somebody tell me out the following 3 categories, where do typical 18650 cells fit?


The first, and by far most common "typical 18650" is the Lithium Cobalt which I list above as:


*a)* *"Unsafe" Lithium Cobalt Oxide (Layered Structure) *



Vikas Sontakke said:


> Lilo (I think that is typo, unfortunately it is all over the internet; lower case "L" and upper case "I" look very similar, so I suspect the original auther intended it to be LiIo and after few re-writes, it become Lilo)


It is a typo. LiIo started out as representing Lithium Ion, and was trying to use the LiPo (Lithium Polymer) format. Because of all the confusion, most sources have changed the abbreviation over to Li-Ion. It can be listed both ways on chargers, and can be given either a 3.6 or 3.7 nominal (nearly discharged) value.


Vikas Sontakke said:


> LiPo (are these the one in typical R/C helicopter?)


Yes. They tend to be rectangular, and have a "putty" characteristic from the polymer design. 


Vikas Sontakke said:


> LiFe (Are these the low voltage rechargeable Lithium?)


Yes. Make sure your charger will accept this 3.2 to 3.3V nominal type, as it is the newest.


----------



## TorchBoy (Aug 13, 2009)

LuxLuthor said:


> Li-Ion ... can be given either a 3.6 or 3.7 nominal (nearly discharged) value.


That reminds me of someone a while back trying to convince me that was the midpoint voltage (ie, mid-discharge), and after starting at 4.2 V actually ended at around 2.5 V. What will a completely flat Li-ion cell measure (not risking any damage)?


----------



## 45/70 (Aug 13, 2009)

LuxLuthor said:


> It is a typo. LiIo started out as representing Lithium Ion, and was trying to use the LiPo (Lithium Polymer) format. Because of all the confusion, most sources have changed the abbreviation over to Li-Ion. It can be listed both ways on chargers, and can be given either a 3.6 or 3.7 nominal (nearly discharged) value.



OK Lux, I may be nitpicking here a bit, but since this is a "sticky" I think some further clarification is needed.

I can go along with the typo part, but you your statement seems to suggest that a LiPo is different than a Li-Ion, when in fact, a LiPo *is* a type of Li-Ion. I also see folks refer to LiFePO4's as something other than a Li-Ion when again they also,* are* a type of Li-Ion.

The other thing that bothers me in this paragraph is that a LiCO's (yes, this is a Li-Ion too ) nominal voltage is 3.6-3.7 Volts. OK, but if a LiCO were "nearly discharged" it would be something <3.0 Volts, under load. This is correctly assuming nominal to mean under load, as opposed to open circuit (OC), which of course is not under load. A reading of 3.6-3.7 Volt OC of a LiCO cell would mean the cell is nearly discharged.

Just trying to help out here. There seems to be enough confusion about Li-Ion cells without bringing it into a sticky. Lux, I will delete the contents of this post, if you prefer, your call. :thumbsup:

Dave


----------



## 45/70 (Aug 13, 2009)

Torch, you beat me to the post, but an open circuit voltage of 3.5 Volts on a LiCO cell is considered "dead". Under load, it's much more difficult to say.

Dave


----------



## Vikas Sontakke (Aug 14, 2009)

This is from the charger manual, please excuse the formatting; I tried sprinkling it with <code> and <table> but that did not parse it.
I used to think that LiPo could be charged at higher charge rate than LiIon but this document says it LiFe which can be charged faster.


Lilo ====
voltage level: 3.6V/cell
max. charge voltage: 4.1V/cell
allowable fast charge current : 1C or less
min. discharge voltage cut off level: 2.5V/
cell or higher
LiPo ====
voltage level: 3.7V/cell
max. charge voltage: 4.2V/cell
allowable fast charge current : 1C or less
min. discharge voltage cut off level: 3.0V/
cell or higher
LiFe ====
voltage level: 3.3V/cell
max. charge voltage: 3.6V/cell
allowable fast charge current : 4C or less
e.g.A123M1)
min. discharge voltage cut off level: 2.0V/
cell or higher


----------



## TorchBoy (Aug 15, 2009)

So from 3.5 V down to 2.5 V a Li-Ion cell has nearly no capacity?


----------



## DM51 (Aug 15, 2009)

TorchBoy said:


> So from 3.5 V down to 2.5 V a Li-Ion cell has nearly no capacity?


Correct. However, this assumes the cell is not under load. If you apply a load to a cell, its voltage will drop - for example by 0.5V. Remove that load, and it will recover within a few minutes to the resting voltage which will indicate its state of charge. If its resting voltage is below 3.5V, it is empty and should be recharged as soon as possible.


----------



## LuxLuthor (Oct 30, 2009)

Added voltage capacity "rule of thumb" for Lithium Cobalt cells to first post.


----------

