CATL-Built Tesla Model 3 Battery Pack Will Use Prismatic Cells

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The battery news keep getting crazier each day. Exactly one week ago, we learned that Tesla might be assembling a battery cell production line in Fremont, then a few days ago that they are buying some battery startups in Denver and even Elon seems to have visited. Then, yesterday, we learned that Tesla in China might use lithium-iron-phosphate (LFP) batteries from CATL* in the Model 3 SR+, and that it’s all made possible by putting cells straight into the battery pack without modules. What we learned in today’s revelation is that those LFP batteries will be prismatic, and the pack might be built — or is at least designed by — CATL utilizing its cell-in-pack technology, something that Tesla is also working on but has thus far not yet implemented. Simon Moores of Benchmark Mineral Intelligence was the first to break the news on Twitter.

Tesla will use prismatic battery cells for the first time in Model 3 short range for Chinese consumers. #EV

This will be made using CATL LFP cells tailor made for Model 3.

It’s the first time Tesla have expanded from cylindrical cells (18650 / 2170) @benchmarkmin

— Simon Moores (@sdmoores) February 19, 2020

Only with LFP batteries

To repeat: Tesla in China will have a Model 3 battery pack that uses prismatic batteries instead of cylindrical ones and also has no modules. When I heard this news, there was only one thing that felt at least somewhat certain, that this is only possible with LFP cells. Most EVs lose their battery capacity after a few years, but Tesla’s hardly lose any capacity. By having so many cylindrical cells working together, each is only taxed slightly during discharge. Also, the batteries have little volume and plenty of surface area for some really good cooling.

In this strange circumstance, Tesla can maintain its quality, reduce the price, and use LFP prismatic cells. While each cell is taxed more, LFP batteries last longer, so that makes up the difference. The main disadvantage LFP batteries have is lower energy density. However, with this rare cell-to-pack technology, we can make up the difference to create the 50 kWh pack that the Model 3 SR+ needs.

Getting a picture of what this will look like

My first research effort was to take a look at the Model 3 battery pack as well as its insides, and then try to calculate what kind of cells will be used as well as how many and in what way they will be placed. Here are the approximate external dimensions of the Model 3’s battery pack: 216.63 cm by 147.32 cm by ~10.5 cm (L x W x H). Inside are 4 modules, each 9 cm high, 29.2 cm wide, and 185.4 cm long for the longer modules.

Here is what we can be somewhat certain of: even without modules, the height of each prismatic cell cannot be more than 90mm, and it is somewhere in that range. Almost all EV prismatic batteries are approximately 48mm thick, in which case we would could fit something like 38 rows of batteries in there. As for how many columns there will be, that could be something like 5 or 6.

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Conclusion

Today’s news will take some time to process. Calculations need to be made and long showers need to be taken before we get any big new revelations about this. If there is one important takeaway from today’s news, it seems to be that the collaboration between CATL and Tesla is more serious than previously thought. It really does appear that CATL did a lot of legwork to design this unique new pack for Tesla without significantly altering the Model 3’s battery pack dimensions.

Either Tesla is going out of its way to make the Chinese authorities happy, or this arrangement really benefits Tesla and CATL, enough to design a whole new battery pack and risk exposing CATL’s cell-to-pack technology to the competition. When it comes to using prismatic cells, there are two concerns: how well these cells can be cooled and what kind of acceleration we can expect with this battery pack. One question that we saw a lot of people ask is, does this technology have a future if energy density can be significantly increased with Maxwell’s dry electrode technology? Who knows?

Have you had any good shower thoughts about what this news could mean? Make sure to share in the comments below.

*Disclosure: CATL was a sponsor of our latest report, Electric Car Drivers: Demands, Desires & Dreams. Dr. Robin Zeng, Founder, Chairman, and CEO of CATL, just recently received a lifetime award from NAATBatt International, the leading trade association for advanced battery technology in North America.