Li-ion cells cycle ageing

[flippy]

chemistry is not even relevant to the end user, only performance matters, and due to the major performance gaps in the same chemistry groups you cant draw any conclusion from it consdiering how differerent cells are.

just look at the raw performance and see what cell is the right one for your application and ignore cool abbreviations.

 

[docware]

To mighty82 : I have checked the chart, seems to be OK, hope you can see the chart now. If not send me PM.

As I mentioned few days ago, another two cells are running the cycling test, Samsung 30Q and LG MJ1. Parameters are the same, charge 1 A, 0,1 A cut-off, discharge 2,5 A, 30Q 4,1 – 3,3 V, MJ1 4,1 – 3,4 V.
Here is brief graphic characterization of both cells at the beginning. It´s interesting to see how MJ1 higher internal resistance affect capacity at 3 A discharge. Thanks to warming of the cell is capacity at 3 A virtually little bit higher, drawing near to 2 A line.

 

[eMark]

chemistry is not even relevant to the end user, only performance matters ...

Thanks to docware's tests some of us are coming around to the realization that differences in NCA 18650 cell chemistry versus NMC 18650 cell chemistry can in fact be a contributing factor to the DCIR performance and possible longevity performance with the cells that docware is testing.

By the way, for what it's worth, your two comments (the one above and the one below) are a confusing contradiction that goes to show your lack of understanding with respect to the importance of a cell's chemistry to a DIY pack's application. A significant factor to consider with respect to cycle life longevity and the cell's DCIR docware is testing to 500 cycles and possibly (Padja's suggestion) to 1000 cycles . A cycle life factor that until docware's ongoing tests had possibly not been as much of a concern by some forum members more interested in "raw performance" than say other members more interested in +500 charge/discharge life cycles.

Docware's tests were never intended just for those only interested in "raw performance" ... rather prolonged cycle results are useful for those DIY applications interested in "performance longevity" moreso than say shorter "raw performance" cycle life (e.g. hopefully at the very least 300 charge/discharge cycles) longevity.

... and due to the major performance gaps in the same chemistry groups you can't draw any conclusion from it considering how differerent cells are.

Docware's recent participation in another forum thread provided insightful replies. The following member post in this same thread also points out the significance of a cell's chemistry to a pack's performance depending on its application ...

"This very informative study shows a higher degradation of their NCA cathode material at higher voltages, leading to increased internal cell resistance" (#23) ... http://budgetlightforum.com/node/47730

just look at the raw performance and see what cell is the right one for your application and ignore cool abbreviations.

The Direct Current Internal Resistance (DCIR) is the sum of a battery's electronic resistances. Docware's DCIR cell tests indicates a battery's internal performance reflecting a cause/affect possible relation to a pack's aging characteristics (longevity performance). An important and significant factor in a DIY cell selection pack build depending on its application. Such at least +500 charge/discharge cycles with daily commuting longevity being the application for the most useful life cycles before End of Life (EoL).

Isn't this what Erik hopefully has in effect accomplished with his longevity daily commuting application when he cancelled his order for 112 (14S8P) PanasonicPF cells (NCA chemistry) in favor of 112 LG Chem M36 cells (NMC chemistry). NMC cells having a lower DCIR and hopefully a prolonged useful cycle life longevity. Docware's tests appear to confirm that NCA chemistry contributes to a higher DCIR (PanasonicPF & SanyoGA) than does the lower DCIR of the LG Chem M29 & LG Chem M36 cells (NMC chemistry) tested by docware.

Frustrated and tired by never ending unfruitful debate about cycle life of various Li-ion cells, I finally decided to start some long term cycling to see the real results.

Instead of furthering frustration, unfruitful debate and seeming contradictions it would really be helpful if we don't dismiss (pooh-pooh) the possible cause/affect relationship of an 18650 cell's chemistry (e.g. NCA vs NMC) as instrumental to noticeable differences in a cell's DCIR (NCA chemistry vs NMC chemistry). Thus a possible contributiing factor to consider what 18650 cells to purchase for a DIY pack build. Especially, if the most important criteria for the DIY builder is prolonging as long as possible (ALAP) the useful longevity cycle life (performance) of a battery pack (e.g. Erik's14S8P Vruzend V2.1 triangular pack build ) ... until finally coming to its End of Life (EoL)

Happy Thanksgiving

 

[john61ct]

Chemistry is indeed important.

But there are huge variations in performance within a given grouping.

Build quality, chemical purity, quality control in the manufacturing process, integrity of the supply chain

every part of the process needs to be just right to create a battery that tests well in real life.

In the end it's the test results that matters, generalizing about the chemistry of each is of limited use.

And, have you confirmed yet that the 29E is NCO?

 

[eMark]

Chemistry is indeed important.

Finally, it was akin to pulling teeth to get someone to finally admit that the apparent DCIR differences between PanasonicPF & SanyoGA (NCA chemistry) versus LG Chem M29 & LG Chem M36 (NMC chemistry) is due in no small measure to their different chemical recipes; especially the inclusion of Nickel which to some extent has been anointed as the premier Li-ion metal ...

Lithium Manganese Nickel Cobalt Oxide2 ~ LiNiMnCoO2 - NMC (INR)
Lithium Nickel Cobalt Aluminum Oxide2 LiNiCoAlO2 -- NCA

Don't get me wrong! This is not to say that NCA is a DCIR dog as it too incorporates Nickel in its recipe. Also being that Tesla is sticking with NCA chemistry (even though Toyota isn't (NMC) it would be premature to write-off NCA chemistry as sub-par to NMC as it's all about application, application, application. We don't know what NCA hybrid recipe Elon and Panasonic may have in the works as progress marches ahead.

And, have you confirmed yet that the 29E is NCO?

Did you mean to say NCA. If so, it is not NCA chemistry, but rather NMC chemistry which is the chemistry of INR 18650 cells (Samsung INR18650-29E). Samsung, Sony and LG are all experimenting and developing next-gen INR batteries with different ratios of manganese, nickel, and cobalt that for the sake of KIS will refer to as NMC. Some other NMC~(INR)18650 cells besides M29 are: Samsung 30Q, Sony VTC6 and LG HE2.

Truth tell, i don't know of another NCA 18650 cell besides PanasonicPF and SanyoGA. You've probably read this already while googling with the reader comment that ... "Samsung 29E is NCM not NCO according to this: (link provided)" but the link listed is no longer available.

Here's Battery University's take on NMC ... https://batteryuniversity.com/learn/article/types_of_lithium_ion
"NMC is the battery of choice for power tools, e-bikes and other electric powertrains. The cathode combination is typically one-third nickel, one-third manganese and one-third cobalt, also known as 1-1-1. This offers a unique blend that also lowers the raw material cost due to reduced cobalt content. Another successful combination is NCM with 5 parts nickel, 3 parts cobalt and 2 parts manganese (5-3-2)."

INR - NMC - Lithium Nickel Manganese Cobalt
This NMC chemistry adds nickel to the IMR chemistry, that has been referred to as a "hybrid" chemistry, but it's been so popular for so long that the days of NMC being a "hybrid" may no longer be as applicable in that it's becoming an industry norm of sorts. Being that both 1-1-1 and 5-3-2 are considered NMC it's more a situation that any 18650 cell that incorporates both Nickel and Manganese is considered NMC until the industry's 18650 BIG Boys (i.e. LG, Samsung, Sony) come up with another "cool" abbreviated 18650 chemistry. Both INR18650-25R and INR18650-29E use NMC chemistry, but they ain't the same critter as progress marches on with NMC "hybrid" recipes and possibly a newer NCA recipe in the new Tesla Cybertruck. :thumb:

 

[john61ct]

TLDR

No I do not mean NMC, nor NCM, CMN, CNM, MNC and MCN

All are very similar, if not different letters for the same nickel + manganese + cobalt combinations.


I mean NCO, aka LiNiCoO2, aka
lithium nickel cobalt oxide

 

[john61ct]

The "INR vs IMR" old spinel vs new spiel I think just confuses things, you'll often see LMO brought into the mix there.

I believe different manufacturers used those text strings in their battery model numbers and marketing materials, referencing different chemistries.

Best to stick with the more canonical compound names.

 

[john61ct]

And Battery University is not a canonical source, I've found lots of inaccuracies and over-generalizations there.

Good for general terminology and 101-level intro for rank noobs though.

Try to find your chemistry IDs from the manufacturers or academic research sources.

 

[john61ct]

i don't know of another NCA 18650 cell besides PanasonicPF and SanyoGA

Panasonic NCR-18650-A, NCR-18650-B, NCR-18650-BD, NCR-18650-BE, NCR-18650PD?

Samsung INR-18650-25R, ICR-18650-30B, ICR-18650-32A, ICR-18650-22F?

Maybe the 29E? 30Q?

Sanyo NCR-18650-BL, NCR-18650-BF?

Even less certain:
LG ICR-18650-D1, ICR-18650-E1
LG INR-18650-MJ1?
LG MH1?

Not sure who maintains this?

https://docs.google.com/spreadsheets/d/1fYjDxxCJXfm2wdpGWCaOUGq8V8TOEgsnplHQa4YQpRQ/htmlview

 

[docware]

Let me refresh the pages with help of few images. PF, M36 and GA after 400 cycles. 29E later.

 

[flippy]

TLDR
No I do not mean NMC, nor NCM, CMN, CNM, MNC and MCN
All are very similar, if not different letters for the same nickel + manganese + cobalt combinations.
I mean NCO, aka LiNiCoO2, aka
lithium nickel cobalt oxide

that is why people should ignore the magic chemistry marketing wank and just look at specs.

 

[john61ct]

 

[john61ct]

No if you can get the accurate objective information, another data point is always useful.

Just don't give it undue importance, and avoid over-generalizing.

Of course the test results are 100x more significant, all-y'all are providing the community a tremendous service, Thank you!

 

[flippy]

i am not generalizing, i hope i am putting things in context.

when spending large sums of money on something you care about the specs, in a car you might find fuel economy/tank size more important then acceleration numbers, but for someone else they might only care about acceleration and not care about the size of the tank. say the difference between someone wanting to build a battery for daily long dinstance driving or someone building a vehicle for drag strips.
both have wildy different needs and in both situations you would not care if the cells are bright pink in color. (replace the color for the chemistry)

playing fanboy on chemistries is litteraly the very least important thing while discussing cells, same goes for brand fanboy-ism like you see with apple or a car brand like audi. frock the brand, does the device/car do what you need it to do? yes, then who cares about the brand or color.

every day i have to listen to people/customers moaning on about how great lifepo4 is because they read it somewere.
one customer wanted LFP cells because they were so robust and refused to hear different. his moped ended up doing 45% of the range he wanted and his battery lasted for less then 4 years as the battery was way too small and the cells were too wimpy to deal with the load. all because of being a chemistry-fanboy....

 

[Pajda]

It sometimes seems to me that the mess with the cathode chemistries actually have manufacturers itselves.

One example is Samsung 30Q. In the cell presentation they marked it as NCA cathode cell. https://eu.nkon.nl/sk/k/30q.pdf but in MSDS (Material Safety Data Sheet) documet, they say that it have NMC cathode... https://www.hoovercommercial.com/media/1513/lithium-ion-battery-safety-sheet.pdf

The same scheme is for Samsung 29E. Samsung presentation say that is NCA, MSDS that it is NMC.

 

[docware]

Re: Optimal Charge Voltage - (LiCo)
Quote
by liveforphysics » Dec 02 2014 3:16pm

„ While I agree NCA is the cat's pajamas, you are attributing too much to the cathode material chemistry. The cathode chemistry itself is neat, and everyone loves to talk about it, but as far as making a cell safe or durable in cycling and calendar life etc, the cathode chemistry is one of the lesser significant factors.

The stuff that makes cells durable and long lasting and safe comes down largely to the surface geometry of the surfaces wetted by the electrolyte, and the electrolyte itself, and even the type and design of the separator.

For example, there are sketchy dangerous short lived LiFePO4 cells, and there are some extremely long-life safe LiCo cells.

While NCA is an awesome cathode material, it is pretty reactive and if you built a cell up with NCA cathode materials and didn't design an optimized particle surface shape and used low-quality hobby-grade electrolyte, and gave it a no-safety features hobby-cell separator, it would make a pretty shitty short-lived potentially dangerous cell.

If you take the NCA cathode material, and then also build a quality cell around it, only then do you get a long lasting durable safe cell. It's not something that auto-magically occurs because the cathode slurry contains NCA.

This is why it's pretty bogus to attempt to draw conclusions about a cells performance or safety or calendar life based around whatever it's cathode material may happen to contain alone."


https://endless-sphere.com/forums/viewtopic.php?f=14&t=65117

 

[eMark]

It sometimes seems to me that the mess with the cathode chemistries actually have manufacturers itselves.

One example is Samsung 30Q. In the cell presentation they marked it as NCA cathode cell. https://eu.nkon.nl/sk/k/30q.pdf but in MSDS (Material Safety Data Sheet) documet, they say that it have NMC cathode... https://www.hoovercommercial.com/media/1513/lithium-ion-battery-safety-sheet.pdf

The same scheme is for Samsung 29E. Samsung presentation say that is NCA, MSDS that it is NMC.

Perhaps, MSDS and Voltaplex got it right. To further add to the confusion let's also include the semi fraternal (not identical) cells of Panasonic PF (NMC) and Sanyo GA (NCA). Perhaps because Panasonic B (NCA) was used in the first Tesla's mistakenly assumed later Tesla's also used NCA, but switched to NMC. Currently Tesla and assume the new Cybertruck both use 21700 cell chemistry. The extra weight and cost of 21700 cells (21mm x 70mm) has yet to be embraced by DIY pack ebikers. The Luna Apex 52v Samsung 28Ah 21700 pack option costs $500 more than the other 52v Panasonic / Sanyo) GA 14Ah Luna Apex pack option ... https://lunacycle.com/luna-apex/ ... Voltaplex rates the Panasonic Sanyo GA (NCA) as a Hot trending cell ... https://voltaplex.com/lithium-ion-battery/18650-battery?s_brand=27&dir=asc&order=name&s_capacity_max=2600-3500&s_chemabv=21

However, according to Voltaplex (Hong Kong) the Panasonic PF is NCM not NCA. Of the current 141 18650 batteries listed by Voltaplex (when uploading) this was their following chemistry breakdown: NCM (74), LCO (31). NCA (17), LMO (12), LFP (7). Panasonic PF (NMC) is 10th row down on right (show 36/page 1) ... https://voltaplex.com/lithium-ion-battery/18650-battery?is_ajax=1&p=3&s_chemabv=29 ... Voltaplex lists the Sanyo GA cell as NCA chemistry ... in middle of third row down (show 36/page) ... https://voltaplex.com/lithium-ion-battery/18650-battery?is_ajax=1&p=2&s_chemabv=21. Could be wrong (wouldn't be the first time) that the only cell docware is testing that isn't NMC is the Sanyo GA which Voltaplex lists as being NCA chemistry.

To see which 18650 cells Voltaplex includes in each of the five chemistries scroll down to see the chemistry selection list on the far left of the page and choose one of the five chemistries to see what cells Voltaplex includes. Voltaplex also lists: M29E, MJ1 and 30Q as NMC chemistry. LG M36 is not included among Voltaplex's 141 five chemistry classifications, but is most likely NMC according to NKON (INR - LiNiCoMnO2) ... https://eu.nkon.nl/rechargeable/li-ion/18650-size/lg-inr18650m36-3600mah-10a.html ... or as john has rightly implied (LNCMO or NCM) as cobalt is the more essential (scarce) ingredient in the recipe than is Manganese. The reason N is listed first in NMC and NCA is IMO because of Nickel being "anointed" as the premier metal in an 18650 cell. When it comes to either "raw performance" or "longevity" Nickel is currently 18650 ebiker king.

Voltaplex also enables one to select a particular brand to see how many different cells in a brand (e.g. 50 LG cells) and price. Ironic that Voltaplex doesn't currently list/stock the LG Chem M36, unless i missed it :?
https://voltaplex.com/lithium-ion-battery/18650-battery?is_ajax=1&p=3&s_brand=30

 

[Dak77]

This post isn't directly related to the point of this thread, but I have some personal experience to share about longevity . Yesterday I hit the 9 month mark on my battery and I have logged 26 cycles of 56.7v to 50v . Now that it's winter, I'll probably be down to 1 or 2 cycles per month until around March. I rarely go above 1c discharge and just brief sprints of 5amps per cell.
This is obviously light usage , but the point is , if you aren't using your bike for daily transportation, you just aren't likely to pile on a lot of cycles and if you are going to build a new pack, 29E has very good capacity from 4.1v > 3.3v , better than most . If like me, you chose the PF , don't sweat. It doesn't start losing capacity until around 115 cycles .(going off Doc's test results) In my case that means I shouldn't notice much capacity loss for about 4 years assuming age doesn't play a big role in degredation. Again, this is only relevant for casual riders , not commuters. Not posting this to derail the hard work of anyone, only to ease the minds of people that have already invested $ in PF.

 

[takyka]

Docware,

What is your DCIR measurement methodology? I want to check my 4 years old battery for comparison.

Thx,


T.

 

[docware]

Docware,
What is your DCIR measurement methodology? I want to check my 4 years old battery for comparison.
Thx,
T.

I measure DCIR according INTERNATIONAL STANDARD IEC 61960-3:2017, paragraph 7.7.3 "Measurement of the internal DC resistance".

Full name of this standard : Secondary cells and batteries containing alkaline or other non-acid electrolytes – Secondary lithium cells and batteries for portable applications – Part 3 : Prismatic and cylindrical lithium secondary cells, and batteries made from them

Description of the DCIR measurement :

7.7.3.1 Measurement
The battery shall be discharged at a constant current of I1 = 0,2 It A. At the end of a discharge period of 10 s ± 0,1 s, the discharge voltage U1 under load shall be measured and recorded. The discharge current shall then be immediately increased to a value of I2 = 1,0 It A and the corresponding discharge voltage U2 measured under load and recorded again at the end of a discharge period of 1 s ± 0,1 s.
All voltage measurements shall be made at the terminals of the battery independently of the contacts used to carry current.
The internal DC resistance, RDC, of the battery shall be calculated using the following formula :
RDC = U1 – U2 / I2 – I1 (Ohm)
Where I1 , I2 are the constant discharge currents U1 , U2 are the appropriate voltages measured during discharge.

Actual example measurement was done in 3 consecutive pulses with 30 s pause for cell cooling down :



Voltage drop measured at the cell :



Samsung 35E DCIR is 30,1 miliohm at 3,82 V and ambient temperature 25 ± 1°C. ACIR at the same conditions is 20,3 miliohm (measured with YR 1030)

Equipment : DC electronic load Maynuo M9712, DMM GW Instek GDM-8351, 4-wires testing fixture BF-2A, thermometer Omega HH520 with K thermocouple.


More details are available here :

http://budgetlightforum.com/comment/1558243#comment-1558243

 

[takyka]

Thank you!

T.

 

[docware]

New batch : PF and GA 500 cycles, M36 475 cyles, 29E7 400 cycles, 30Q 111 cycles, MJ1 82 cycles.


View attachment 4

View attachment 2

 

[Cephalotus]

Thanks a lot for the updates!

It doesn't take so much time to do 500 cycles, so I hope you will continue to 1.000 cyles and maybe even more in case of cells that show very little aging up to that...

LG MG36 shows amazing performance so far.

 

[Dak77]

You guys are awesome. Thank you Doc, Pajda, and Flippy for your work. That M36 does look amazing and MJ1 seems to follow in its tracks . And 29E beating the brakes off the PF. Nice . Can't wait to see how the 30q does after 300 or so, if you decide to take it that far.

 

[Shunt]

If this goes to 1k , my money is on 29E to finish with the highest capacity. His results basically reinforce everything Flippy has posted many times.