# Would 4680 cell, LFP, have similar performance to 2170, NMA cell pack?



## bwilson4web (Mar 4, 2019)

Idle speculation but I'm wondering if the improved 4680 package can be equivalent to current 2170 NMA cells in a pack?

Bob Wilson


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## m3_4_wifey (Jul 26, 2016)

It might help if you defined performance. I'm going to assume charge rate, which should be faster with 4680 due to the lower resistance and heat created during charging. I have no idea how many different chemistries they are going to use with the 4680 (4680 is a form factor), or if the 2170 is going to stick with NMA.


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## bwilson4web (Mar 4, 2019)

Correction, NCA (Nickel Cobalt Aluminum) chemistry in 2170 cells.

Source_1:
https://cleantechnica.com/2020/09/22/everything-you-need-to-know-about-teslas-new-4680-battery-cell/

_The larger jelly roll packs more active battery material into the casing for a 5× improvement in energy storage and a 6× increase in power. Scaling up to the pack, the new form factor alone delivers a 16% increase in range. _​_..._​_eliminating the tab actually makes it easier for electrons to get around inside the cell than in the current 2170 cells. "You actually have a shorter path length in a large tabless cell than you have in a smaller cell with tabs," Musk said._​_..._​_the battery cell._​

_*14% improvement in cost/kWh* *coming from the change in cell form factor.*_
_*18% improvement in cost/kWh as a result of the 10× manufacturing footprint reduction and 10× manufacturing energy consumption reduction*. The new dry manufacturing process enables pressing the active battery powder material directly into a film. The new manufacturing process is based on Maxwell Technologies' proprietary "proof of concept" process. Process is not at production scale yet, but there is a "clear path" to large scale production._
_*5% improvement in cost/kWh coming from the increase utilization of silicon in the battery cells*._
_*12% reduction in cost/kWh* *coming from improvements in the cathode material*._
_*7% improvement in battery pack cost per kWh as a result of Tesla's new integrated vehicle design*. Tesla redesigned its vehicles using new front and rear castings that integrate with the battery pack. To accomplish this, Tesla developed a completely new alloy to enable casting of some of the largest components in the automotive space. These bolt directly into a new "structural battery," eliminating the need for redundant, parallel elements in Teslas._
Source_2: https://en.wikipedia.org/wiki/Lithium_nickel_cobalt_aluminium_oxides

_The usable charge storage capacity of NCA is about 180 to 200 mAh/g ... lithium iron phosphate LiFePO4 with 165 mAh/g_​
Based on this:

(165 - 180) / 180 = -8.3 % lower energy density
(165 - 200) / 200 = -17.5% lower energy density
16% improved range from 4680 form factor
Off hand, it looks like a 4680 LFP pack will have similar performance to a 2170 NCA pack ... but more affordable.

Bob Wilson


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## JasonF (Oct 26, 2018)

I think the 4680’s are trying to match 3 different goals…

The larger each individual cell is in the pack, the easier and cheaper it gets to manufacture it. That’s in large part the goal behind 4680 - bringing the cost of the pack down by physically having fewer cells to manufacture and install.

As a side bonus, fewer cells in the long run will make the packs less prone to failure just because of the rule of random odds.

Next goal would be making the battery chemistry out of more easily obtainable and price stable materials. This is where LFP wins so far. It has more weight and less energy density, but if it can be used in 4680’s so it’s “good enough” it might be the winner. Especially since you can use 100% of the battery daily, so you only get lower range compared with other cells on long trips.

And the third goal, the “eventually”, would be to someday switch the cells to a chemistry where even fewer cells need to be in the pack to perform the same or better. If there is a large difference in the number of required cells, they could even sacrifice some sustainability and cost per cell for the greater goal of a smaller, cheaper, lighter pack.


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## m3_4_wifey (Jul 26, 2016)

bwilson4web said:


> Off hand, it looks like a 4680 LFP pack will have similar performance to a 2170 NCA pack ... but more affordable.
> 
> Bob Wilson


The 4680 is NOT going to be limited to LFP. I think the plan is to make 4680 NCA batteries for their long range vehicles including the Tesla semi where weight is extremely important. They will try and reduce their dependency of cobalt over time.

They are trying to switch all standard range cars over to LFP because they have the space and the reliability is better. I would assume the form factor of the standard range cars with LFP is still 2170, and they will switch over to the 4680 form factor with LFP chemistry eventually.
I think that Tesla will give the bump up in the range of the standard range cars when they switch to the 4680 form factor just to make the new cars better than the previous cars. A 16% increase in range could be a real compelling amount!


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## JWardell (May 9, 2016)

I don't think 4680s will be made in LFP at all. At the moment all the LFP packs are prismatic/pouch CATL cells. And that seems to remain the plan with only SR 3s getting them, just moving to worldwide.
LFP has some very different voltage curves and power capabilities, so I think it's nowhere close to comparing apples to apples.


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## GDN (Oct 30, 2017)

Wasn't one of the big differences in the 4680 the continuous tab - removes the single tab which is a bottleneck for charging/discharging. So they should be able to improve charge time - easier to get the energy into the cell and possibly get better "Performance" by getting a bigger jolt out of the battery for launches, etc.


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## garsh (Apr 4, 2016)

JWardell said:


> I don't think 4680s will be made in LFP at all. At the moment all the LFP packs are prismatic/pouch CATL cells. And that seems to remain the plan with only SR 3s getting them, just moving to worldwide.


Has anybody seen a teardown of a Tesla LFP battery pack yet?


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## iChris93 (Feb 3, 2017)

JWardell said:


> I don't think 4680s will be made in LFP at all. At the moment all the LFP packs are prismatic/pouch CATL cells. And that seems to remain the plan with only SR 3s getting them, just moving to worldwide.
> LFP has some very different voltage curves and power capabilities, so I think it's nowhere close to comparing apples to apples.


I would be surprised to learn they're using pouch cells after this tweet. 

__ https://twitter.com/i/web/status/1433670656315600919


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## JasonF (Oct 26, 2018)

iChris93 said:


> I would be surprised to learn they're using pouch cells after this tweet.


I would guess there's a large chance that they are prismatic, because those will fit into the same battery pack design as the current Model 3/Y. Pouches would require a massive redesign of the pack itself, notably the retention system for the cells and cooling system.


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## iChris93 (Feb 3, 2017)

JasonF said:


> I would guess there's a large chance that they are prismatic, because those will fit into the same battery pack design as the current Model 3/Y. Pouches would require a massive redesign of the pack itself, notably the retention system for the cells and cooling system.


I'm not very familiar with prismatic cells. Are those just pouches in a prismatic enclosure?


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## JasonF (Oct 26, 2018)

iChris93 said:


> I'm not very familiar with prismatic cells. Are those just pouches in a prismatic enclosure?


They're just like round cells, but shaped like prisms (3 edges). They will fit in slots made for round cells.


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## TrevP (Oct 20, 2015)

Going back to battery day last year Tesla posted this graphic on the large screen detailing their plan going forward.

3 chemistries:
LFP
NM
High nickel

Formats are going to be mixed (18650, 2170, prismatic, 4680). It's entirely possible they will mix and match to their needs but for the moment LFP are going into SR+ cars, NM which includes 18650, 2170 & 4680 are going into 3/Y/S/X and the high nickel 4680 are destined for the CT, Semi & possibly the Roadster


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## JWardell (May 9, 2016)

garsh said:


> Has anybody seen a teardown of a Tesla LFP battery pack yet?


Monroe did show it toward the end of a video.






Also first use of Tesla Flex circuits instead of wires.


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## iChris93 (Feb 3, 2017)

JWardell said:


> Monroe did show it toward the end of a video.
> 
> 
> 
> ...


Those don't look like prisms to me? What am I missing?


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## bwilson4web (Mar 4, 2019)

There are technical details I would like to learn about the LFP cells. For example, thermal management.

My first impression was the battery pack is a "sack of potatoes' as there is no evidence the cells are structural. We really need to see individual LFP cells disassembled. Also, the previous Tesla batteries had multiple cells wired in parallel. Loss of one cell was no big deal Are there multiple LFP cells in parallel?

Bob Wilson


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## garsh (Apr 4, 2016)

iChris93 said:


> Those don't look like prisms to me? What am I missing?


"Prismatic cells are contained in a rectangular can."

https://www.epectec.com/batteries/prismatic-pouch-packs.html


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## JasonF (Oct 26, 2018)

iChris93 said:


> Those don't look like prisms to me? What am I missing?


Pouches are very long, they're not cell sized. Prismatic fits into the same space as round cells, except maybe that you could put two in the space where one round one would fit.

That's why Elon Musk pointed out that pouches are more prone to thermal runaway, because there is a lot more chemical content in one isolated space to ignite. Some companies use them for that reason - because a lot more battery can fit into a smaller space.


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## garsh (Apr 4, 2016)

An LFP prismatic module (screenshot from the Munro Live video).


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## iChris93 (Feb 3, 2017)

garsh said:


> "Prismatic cells are contained in a rectangular can."
> 
> https://www.epectec.com/batteries/prismatic-pouch-packs.html





iChris93 said:


> Are those just pouches in a prismatic enclosure?


rectangular can?


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## TrevP (Oct 20, 2015)

Prismatic cells are not “prismatic” in shape as the name would suggest. It’s just another name for a pouch (think pop tart or MRE bag)


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## M3OC Rules (Nov 18, 2016)

According to this site the difference between prismatic and pouch is that the prismatic have an aluminum or steel casing. Neither have standard sizes but are rectangular boxes of varying thicknesses. Pouch cells can get thin enough to be flexible.

https://batteryuniversity.com/article/bu-301a-types-of-battery-cells


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## iChris93 (Feb 3, 2017)

M3OC Rules said:


> According to this site the difference between prismatic and pouch is that the prismatic have an aluminum or steel casing. Neither have standard sizes but are rectangular boxes of varying thicknesses. Pouch cells can get thin enough to be flexible.
> 
> https://batteryuniversity.com/article/bu-301a-types-of-battery-cells


Thanks! Maybe that is why they will use prismatic cells even when Tesla recommends against pouch cells.


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## bwilson4web (Mar 4, 2019)

My first traction battery experience was with Prius, prismatic batteries. 

The Prius traction battery pack requires compression rods to deal with the density changes from charging and discharging. In contrast, a cylinder battery contains the dimensional changes without the need of a more complex battery pack. The problem is more severe with pouch cells as a prismatic cell housing might be engineered to limit dimensional changes ... which the Toyota NiMH modules did not.

Bob Wilson


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## JWardell (May 9, 2016)

Yeah, they're all pouch cells in my book. Even if metal, the casing is not rigid like a cylindrical battery cell. Of course you learned the physics of how much stronger a beer can is than a flat sheet long ago, right?
While cell batteries are dangerous if pierced, pouch cells can short if simply bent and even with thermal expansion. That's why they are much less safe for something like a car. 
But, LFP is fundamentally much safer than other lithium ion chemistries, and is much much more difficult to set fire to, you can literally shoot and stab them. Therefore, LFP pouch cells present much less of a fire risk.
LFP however requires much more mass per unit of capacity, and also has less power output. So it's not a good choice when weight or size is a limitation, which used to be the case in cars. Not good for high performance, not good for max range. But PERFECT for lower cost, lower range cars, which happen to have plenty of leftover space from the larger range packs!
So tesla can afford the wasted space, and a bit extra mass to move standard [range] models over to lithium iron phosphate pouch cells, and therefore give them an entirely second source for batteries for these cars, freeing up the higher performance cells for more production of the long range cars. Big win for Tesla.


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