1. 20 mkm is not very thin and should be visible in this scale (layer 2 is about 40 mkm).

2. Disassamble of cell is fire safe in case of full discharge of battery (LiCoO2 (or modern clone, like NMC etc.) and C, in case of full charge there are LixCoO2 and LiC6 - very reactive mix). Electrolyte vapor is more dangerous (inhalation). I advise you to deep freeze (e.g. in liquid nitrogen bath) a fully discharged battery. After that, cut it with a thin disk (quickly). After that, you can even cover the incision with epoxy resin and polish it after hardenying (at least you will see colors) ... Everyone does it ...

3. Dr. Jose Miguel Campillo Robles are true - the manufacturer can only be trusted in a pinch.

Hello Bence,

Check this paper (figure 1):

https://www.researchgate.net/search.Search.html?type=publication&query=Modelling%20of%20cracks%20developed%20in%20lithium-ion%20cellsunder%20mechanical%20loading

It seems that negative electrodes are higher. Therefore, 1+2+3 seems to be the negative electrode (1 and 3 the active material of negative electrode and 2 cupper current collector), and 4+5+6 the positive electrode (4 and 6 the active material of positive electrode and 5 the aluminum current collector).

Regards

Thank you.

I sent a request to get access to the paper, however, I have found another proofing article that validate your thought.

Regards,

Bence

It seems to me that Dr. Jose Miguel Campillo Robles is right, but there is an important clarification. Between layers 3 and 4 (1 and 6) there should be a separator. In this case, it is not visible. Most likely it is a lithium polymer (LiPo) battery, therefore polymer layer is very thin. It is necessary make XPS elemental analysis on profile 1-6, then all questions will disappear. It will be possible to determine the compositions of all layers. If you compare the pictures for the charged and discharged state of the battery - in general, you can extract a lot of information.

Hello Vadim,

thanks for your reply. It is actually a Samsung 18650-26F Li-ion cell utilizing LCO cathode, probably. The cathode type comes from the manufacturer's datasheet/vendor website.

Actually, the separator is very thin (~15-25um guess) that is true and it's made me confused. It's supposed to be in between typically 30-50um in commercial Li-ion cells as I know.

What do you think?

Bence, have you open the cell? I think it is the best option to check all this

I am afraid of explosion that's why I rejected this idea so far.

I was wondering if I fully discharge the cell with low currents to put the cell in a lower energy state and then, cut the top and the bottom end off with a blade/knife avoiding to short the electrodes/collectors with the blade. Then, it could be rolled out to check the layers.

What do you think, can I manage to do this without using vacuum/inert atmosphere?

It is not recommended because of exothermic reactions... but I have do it in my garage... ;-)

However, in a globebox you will mantain all the elements as they are inside the battery. Out of the globebox some materials will react and thicknesses will not be the real ones.

The garage project sounds interesting (& tempting). :)

Unfortunately, I don't have a glovebox laying around but I am going to have a look at in other institute.

---

What do you think actually, can I trust in the manufacturer's data about coding electrode type such as INR, IMR, ICR, IFR?

As I know, it should cover NMC, LMO, LCO and LiFePo types respectively even NCA and NCO is missing from the list. I have found that vendors' data is usually misleading and not consequent in this context.

Don´t trust the manufacturers datasheet... Usually there are some differences due to additives or blending of active materials. For example, most of officially LMO (IMR) batteries are blended with NMC to increase the capacity and lifetime of the cell:

Article Synergies in blended LiMn2O4 and Li[Ni 1/3Mn1/3Co1/3]O2 posi...

Recently, we have proved that blended active material is present in the case of one commercial 26650 LMO battery. We have used Battery Design Studio software (Siemens) to check it.

Great. Thank you.

1. 20 mkm is not very thin and should be visible in this scale (layer 2 is about 40 mkm).

2. Disassamble of cell is fire safe in case of full discharge of battery (LiCoO2 (or modern clone, like NMC etc.) and C, in case of full charge there are LixCoO2 and LiC6 - very reactive mix). Electrolyte vapor is more dangerous (inhalation). I advise you to deep freeze (e.g. in liquid nitrogen bath) a fully discharged battery. After that, cut it with a thin disk (quickly). After that, you can even cover the incision with epoxy resin and polish it after hardenying (at least you will see colors) ... Everyone does it ...

3. Dr. Jose Miguel Campillo Robles are true - the manufacturer can only be trusted in a pinch.

Thank you, Vadim.

According to my calculations, the separator thickness should be around 30 um. The CT photo is quite blurry in that region and I suppose that the separator area should not be a distinct layer rather it should have a smooth and labyrinthine transition into the electrodes. Considering these, the separator length I estimated comes from a statistical approximation.