Wow!!! I can't believe I had to login to get an answer to this :)

[Derek Dean]

As always with CPF, I too have learned a lot from this thread. Thanks for sharing your experience with us, cheaperrooter : )

 

[TinderBox (UK)]

]Actually...I am a very stupid man!!![/B] Spent most of my day trying to figure out what the voltages are on a new CR123a, when I remembered I ordered 100 new surefires, and all I had to do was test them!
SMH at myself in shame. I'm just glad I figured that out before anybody out there in candleland did

Ok, so new is 3.25. So in other words my Duracell's have not lost ANY voltage as they are the exact same as my NEW surefire. And the titanium's are only 3.10.

Hmmmmmmm. Wondering now if maybe I have something going on with my thermal imager and its draining batteries much faster than it should???

Totally UNTRUE, We don't let stupid people register in the first place (only kidding) As they say the only stupid question are the ones you do not ask, I find i am wrong all the time and i am a better man for the correction.

Welcome to CPF.

John.

 

[iamlucky13]

Lithium chemistry involves passivation. When the layer is thin it offers the benefit of extended shelf life. When the layer get thicker it can interfere with performance.

Here is an article that talks about this.

Tom

That was interesting and answered a puzzle I encountered. I have a coin cell light (2 x CR2016) that sat in a drawer for a few years. When I tried using it again, it was about as bright as the dimmest firefly mode on any flashlight I own (0.1 lumen), despite measuring 3V on each battery. They must have had a fairly heavy passivation layer, and the low current the light was drawing under those conditions probably wasn't enough to remove the layer.

 

[cheaperrooter]

I apologize to everyone who supplied me with some excellent answers and links for research. I started reading those links and one thing led to another and next thing I knew I just branched off in to other things and totally forgot to come back and check this thread to thank everybody!!!!

So thank you everyone

 

[Gauss163]

Lithium chemistry involves passivation. When the layer is thin it offers the benefit of extended shelf life. When the layer get thicker it can interfere with performance. Here is an article that talks about this.

That was interesting and answered a puzzle I encountered. I have a coin cell light (2 x CR2016) that sat in a drawer for a few years. When I tried using it again, it was about as bright as the dimmest firefly mode on any flashlight I own (0.1 lumen), despite measuring 3V on each battery. They must have had a fairly heavy passivation layer, and the low current the light was drawing under those conditions probably wasn't enough to remove the layer.

Worth explicit emphasis: the passivation and voltage-delay effects discussed in the linked article apply only to primary (nonrechargeable) Lithium batteries, viz. Li-SOCl2 (Lithium Thionyl Chloride), not to secondary (rechargeable) Li-ion batteries.

I stress this in case anyone stumbles into the middle of this thread via a web search - possibly missing the earlier primary-cell context (which is also completely missing in the linked article, so could easily be misinterpreted as applying to rechargeable Li-ion batteries). Being more explicit helps to avoid the common confusion between primary Lithium-metal vs. secondary Li-ion cells.

 

[SilverFox]

Hello Gauss163,

Thank you for pointing out that there are differences between primary and rechargeable lithium cells.

I will point out that the original post stated primary cells, the linked reference stated LiCl chemistry which is not rechargeable, and at the end of the linked article there was a link to an Electrochem article that explicitly states primary cells.

It is interesting that this article mentions the passivated surface film layer on the electrodes as an aging issue on rechargeable LiIon cells.

Do you have any data that supports passivation is not an issue with rechargeable lithium cells?

Tom

 

[Gauss163]

[...] the linked reference stated LiCl chemistry which is not rechargeable

It doesn't "state LiCl chemistry" (that does not exist). Rather, it mentions an LiCl passivation film. Most non-experts won't be able to infer from this esoteric phrase that much of what is written in the linked article only applies to primary (nonrechargeable) lithium batteries, viz. Li-SOCl2 (Lithium Thionyl Chloride) chemistry.

[...] Do you have any data that supports passivation is not an issue with rechargeable lithium cells?

No one claimed that. The point is that the SEI passivation layer in Li-ion cells behaves very differently - so much so that much of what is written in the linked article does not apply to secondary (rechargeable) Li-ion batteries, e.g. they have no analogous voltage-delay, nor >10-year shelf-life, etc.

As you probably know, there is widespread confusion between primary Lithium and secondary Li-ion batteries. One can help to impede further such confusion by adding explicit context when it is lacking (or not trivial to infer). Hence my prior post.

 

[SilverFox]

Hello Gauss163,

Let's see now... You are correct that LiCl is not a chemistry but forms as a degradation of the electrolyte. Thanks for pointing that out.

However, in your zeal to protect the person that suddenly stumbles on this thread, do you think that when they look up LiCl and passivation they will be pointed to primary or secondary batteries?

In the interest of protecting anyone who stumbles in here should we also add that stored energy can be dangerous? Or is that too obvious.



I have actually witnessed similarities in the passivation layer in primary and secondary cells related to the cells performance during testing. When subjected to a load a primary cell with a passivation layer will show higher impedance which results in a dip in the voltage under load curve. I see the same dip in secondary cells that have had the opportunity to develop a passivation layer which is the SEI layer.

Both types of cells improve after the passivation layer is burned off. Both types of cells show a loss of capacity after passivation layers have had a chance to grow to any depth.

A while back the idea of improving the shelf life of lithium primary cells involved applying a specified load to the cells periodically. The load was designed to burn off the passivation layer while using a minimum amount of capacity. I don't know if anyone actually does this. Most simply look at the 12 year shelf life and work around that.

I wonder how something similar would work with secondary cells? For example storing secondary cells at the less than optimal voltage of 4.0 volts will result in the SEI passivation layer forming. Can periodic loads be applied to offset the growth of this layer?

Tom

 

[Gauss163]

[...] I have actually witnessed similarities in the passivation layer in primary and secondary cells related to the cells performance during testing. When subjected to a load a primary cell with a passivation layer will show higher impedance which results in a dip in the voltage under load curve. I see the same dip in secondary cells that have had the opportunity to develop a passivation layer which is the SEI layer. Both types of cells improve after the passivation layer is burned off [...]

Hi again Tom. I recalled this thread after the recent thread about "breaking in" Li-ion cells. It would be very interesting to know more details about what you observed about the passivation layer being burned off in Li-ion cells. While this is a well-known process nontrivially affecting primary Lithium cells (see above), I'm not aware of any studies that report analogous nontrivial behavior for Li-ion cells during normal conditions. If you are able to supply further details on your observations then they may prove of interest in the linked recent thread.

I wouldn't be surprised if the source of some of these "breaking in" recommendations for Li-ion in the RC/hobby world are due to said confusions, i.e. confusing recommendations for primary Lithium cells vs. secondary Li-ion cells.

 

[SilverFox]

Hello Gauss163,

The secondary cell observations came from older cells that were most likely damaged or worn out to a great extent.

In one case I had some Sony Li-Ion round cells that had a max charge of 4.1 volts. I was looking at increasing capacity by charging to 4.4 volts. I actually observed about a 20% increase in capacity at a lower discharge rate (about 0.5C) but life cycles were reduced to below 10. At higher discharge rates (about 2C) the discharge curve started with a huge drop in voltage followed with a rise and then a more normal drop off under the load. This curve looked a lot like that from a stored primary cell.

After reviewing the safety issues with over charging I abandoned this project. Fortunately I had no incidents and I recycled the cells to further minimize any risk from them.

Tom

 

[Gauss163]

^^^ Ah, the cells were older, unhealthy/damaged, and overcharged by 0.3V (not "normal conditions") so it is not so surprising that they exhibited abnormal behavior. Glad to hear that your (possibly dangerous) experiment ended safely.

 

[Gauss163]

Revisiting this thread I just noticed that I missed a couple of your questions, so I'll address them now.

Let's see now... You are correct that LiCl is not a chemistry but forms as a degradation of the electrolyte. Thanks for pointing that out.

However, in your zeal to protect the person that suddenly stumbles on this thread, do you think that when they look up LiCl and passivation they will be pointed to primary or secondary batteries?

In my experience many (most?) readers don't bother chasing links or doing further research (some even loudly complain about having to expend such extra effort). So if we don't explicitly add this contextual info then these readers may be left with the wrong ideas (I suspect that is one of the major reasons behind the general public's common confusion between primary and secondary Lithium battery properties). So - as above - whenever I see discussion of topics that may lead to such misunderstandings I often add a remark to help prevent such.

In the interest of protecting anyone who stumbles in here should we also add that stored energy can be dangerous? Or is that too obvious.

As you surely know, I am one of the major proponents here of proper safety education so I do in fact do so when it is pertinent. But you probably don't want to encourage me to be even more vocal about safety! (I already overemphasize a bit in order to balance against common reckless advice all over the web). But maybe you were joking...

I have actually witnessed similarities in the passivation layer in primary and secondary cells related to the cells performance during testing [...] I wonder how something similar would work with secondary cells? For example storing secondary cells at the less than optimal voltage of 4.0 volts will result in the SEI passivation layer forming. Can periodic loads be applied to offset the growth of this layer?

I don't recall seeing any research on such matters. If anyone has any hard data then please share. It would be interesting to more precisely quantify the (large) differences in behavior between passivation in primary vs. secondary Lithium batteries, and to better understand the role played by the variations in chemistry.