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Tabless design cylindrical cells tests

Pajda

10 kW
Joined
Jan 24, 2016
Messages
575
Location
Czech Republic
Comming soon!

Disclaimer: The tested EVE INR21700 40PL sample is most likely still a pre-production sample. This one has been disassembled from the customer battery pack. I only got this sample through sheer fortune and the support of the ES community.

EVE 40PL samples as arrived:
20231123_120127.jpg
20231123_120137-2.jpg

Test setup:
- EVE 40PL sample was dressed into standard shrink tube with plastic isolator on the positive terminal.
- ca 5.5 mm^2 cross-section copper strips (11 mm wide with a thickness of 0.5 mm) were welded with the use of Micro-TIG welder to all three competitors (Molicel P30B, P45B and EVE 40PL)
- 6 mm^2 (power) and 0.5mm^2 (sense) Cu wires, ended witch cable lugs with M5 screw, were used for 4-Wire connection with the battery tester.
- Only EVE 40PL is shown as example.
20231123_120034.jpg20231123_115946.jpg


Data Table:
HP_tabless_0.5C-1C_100%DoD_cycle_life_test@table.png
Cycle life
HP_tabless_0.5C-1C_100%DoD_cycle_life_test@capacity.png
HP_tabless_0.5C-1C_100%DoD_cycle_life_test@DCIR10s.png



Results after 1000 cycles at 5C discharge at 100% DOD
10C_voltage_drop_FC_new+1000cyc.jpg

5C_voltage_drop_FC_new.jpg 10C_voltage_drop_FC_new.jpg 25C_voltage_drop_FC_new.jpg
5C_temperature_rise_AC_new.jpg 10C_temperature_rise_AC_new.jpg
5C_cycle_life_test@capacity_drop.png 5C_cycle_life_test@DCIR10s_rise.png
 
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Comming soon!

Disclaimer:
The tested EVE INR4695P sample is most likely still a pre-production sample. This one has been disassembled from the customer battery pack. I only got this sample from Vapcell Company
 

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Comming soon!

Disclaimer:
The tested EVE INR4680 sample is most likely still a pre-production sample. This one has been disassembled from the customer battery pack. I only got this sample from Vapcell Company
 

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How did you manage to get the EVE 40PL?

I've been trying to get my hands on it for months at this point.

Still, I'm very excited about such a cell. It seems like it's the tabless(foil all tab) design that's giving it the edge, and not the chemistry all that much honestly.
 
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Yeah. As it turns out, the 100A claim by EVE might not be feasible without liquid cooling.
One thing I've noticed though is that beyond 5C, the capacity loss becomes much smaller, indicating that the hotter cell has much lower internal resistance.
Wow I am so excited for this, thanks! I would be so happy to see you test murata VX40 cells, they should perform even better than these EVEs imho.
This may indicate that Murata may have an even more capable electrolyte/cathode mix that would enable even higher performance.
 
I already ran the tests at 100A continuos with 80°C Tcut at the cell body side for both 21700 competitors. I hope that full data with complete test setting will be available this weekend but no promise. In short:

40PL runtime at 100A is: AC (without forced air cooling) @ 62 sec and FC (forced air cooling) @ 86 sec, both to the 80 °C Tcut
P45B runtime at 100A is: AC (without forced aircooling ) @ 44 sec and FC (forced air cooling) @ 58 sec , both to the 80 °C Tcut

40PL manage to stay above 3.00V at 100A load, P45B above 2.78V
 
I am a huge fan of the tabless design. Of course the focus right now is on using these for cars, but I feel that one of the most important characteristics of the design is that it reduces localized hot-spots in the common tabs, which in the past have acted as bottle-necks to current.

Heat is one of the factors that decays the range of any battery chemistry. The tabless cell design significantly reduces one of the physical causes of hot spots inside cells.

I have not yet seen an example of a tabless LiFePO4 cell, but I feel that the tabless design will allow tabless LiFePO4 cells to produce more current, and to last even longer than they do now.
 
Yes, and all-tab foils (tabless designs) also have the unintended side effect of improving cycle life even at lower currents since it improves internal cell thermal homogeneity and initial build stresses. This can be seen even in non classical foil tab designs:

IMO, the biggest benefits of tabless designs will be seen in HE cells where tabs are sacrificed for maximum energy density. With our current cathode chemitries, just getting the current out efficiently is a big bottleneck, so decreasing resistance there has huge benefits.
 
I am a huge fan of the tabless design. Of course the focus right now is on using these for cars, but I feel that one of the most important characteristics of the design is that it reduces localized hot-spots in the common tabs, which in the past have acted as bottle-necks to current.

Heat is one of the factors that decays the range of any battery chemistry. The tabless cell design significantly reduces one of the physical causes of hot spots inside cells.

I have not yet seen an example of a tabless LiFePO4 cell, but I feel that the tabless design will allow tabless LiFePO4 cells to produce more current, and to last even longer than they do now.

We are also seeing them in some tools packs, so they will leak to DIY market relatively soon :)
 
I'm just absolutely floored that you can rip 100A out of a 21700-size cell in the first place. It's additionally surprising to me that the cells held up as well as they did (even for a single cycle!) in your 12.5C tests.

Time and again, Pajda, you find new and creative ways to put your tools to work and perform really interesting tests. Thank you for sharing your findings with ES.
 
One more thought. Data from EVE 4680 sample will be available later, because unfortunately Vapcell this time messed the welding process of nickel strips. They they made the schoolboy mistake when used CD welder rather than laser used on 4695 sample, where CD welded nickel has no chance to properly stick on the aluminium positive terminal. So I am now waiting for my partners with laser welding machine to process aluminium strips.

Before got the EVE4695P results I was thinking about using of something like a 1mm thick and 15mm wide laser welded aluminum strip (15mm is the diameter of the Al positive terminal on 4680) = 15mm^2 which could be equivalent to circa 10mm^2 Cu to go up to 10C (250A), but now I am expecting similar results here as well.
 
small update, Molicel P30B finished 1000cycles and added table data for both Molicels, hope I will add discharge graphs soon as well. EVE40PL is still alive but not for long.
 
small update, Molicel P30B finished 1000cycles and added table data for both Molicels, hope I will add discharge graphs soon as well. EVE40PL is still alive but not for long.

Thanks, P30B doesn't look bad at all, 75% remaining capacity after 1000 cycles at 4.2v charge and 5C discharge.
 
It’s unfortunate that Vapcell encountered issues with the welding process for the nickel strips on the EVE 4680 sample. Using a CD welder instead of a laser welder can indeed lead to suboptimal results, especially when attaching nickel to aluminum. ArchiCAD 26 software for 3D modeling. Waiting for your partners with a laser welding machine to process the aluminum strips sounds like a prudent approach. Laser welding tends to provide better precision and reliability.
 
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It’s unfortunate that Vapcell encountered issues with the welding process for the nickel strips on the EVE 4680 sample. Using a CD welder instead of a laser welder can indeed lead to suboptimal results, especially when attaching nickel to aluminum. Waiting for your partners with a laser welding machine to process the aluminum strips sounds like a prudent approach. Laser welding tends to provide better precision and reliability.
Try jewellery welder and maybe cooper will do better ..
 
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