Tesla 21700 cells - same but different?

I've been trying to find a blog or something on the interwebs about the energy density of the Panasonic 21700 cells used in the Model 3.

We know that the volume of the cell has gone up by ~50%, so there's more mass as well, and therefore, more active material.

The proportion of non-active material to active material is probably slightly lower, giving a minor improvement to energy density.

But it seems the overall cell level energy density if probably still around about the 220-240 Wh/kg mark.

Some fanboi sites are talking about >300 Wh/kg and >800 Wh/l. I'm not convinced the chemistry or assembly is all that different...

Can some one grab a cell off Jack Rickard and do a charge-discharge test? And weigh it too?

https://www.aliexpress.com/item/35pcs-lot-freight-free-to-USA-EU-21700-M50-INR21700-M50-new-model-battery-M50/32855890973.html?spm=a2g0s.13010208.99999999.312.4d433c00xYAzHk


I don't know if the Tesla cell has more than 5Ah. But if we take the one above for example you can calculate the specs from that one.

Wh per cell: 18.5Wh
69g/Cell
that is almost 270Wh/kg

A Tesla cell would need to be 5.5Ah to be at 290Wh/Kg or lighter than 69g/Cell.

Way back in the Mod 3 discussion, we figured the new Tesla cell was 4.8-4.9 Ah based on the EPA paper ( 80.5 kwh) and known cell count (4416).
So unless tesla have managed to significantly reduce the cell weight below the 68-69 gms of all other 21700 cells, then there is not much improvement in energy density ...if any...over 18650s.
https://insideevs.com/new-tesla-model-3-battery-details-images-released/

jonescg said:

I've been trying to find a blog or something on the interwebs about the energy density of the Panasonic 21700 cells used in the Model 3.

Click to expand...

Very fun. Are these not ebiker "secret words" for lowest cost per mile overall? :wink:

Hillhater said:

Way back in the Mod 3 discussion, we figured the new Tesla cell was 4.8-4.9 Ah based on the EPA paper ( 80.5 kwh) and known cell count (4416).
So unless tesla have managed to significantly reduce the cell weight below the 68-69 gms of all other 21700 cells, then there is not much improvement in energy density ...if any...over 18650s.
https://insideevs.com/new-tesla-model-3-battery-details-images-released/

Click to expand...

Or they have managed to match the performance of the 18650 benchmark despite a larger format cell and won by significantly reducing the part count.

The larger capacity means lower part count - it's just logical. But the cylinders are still cheaper and easier to mass produce than pouches or prismatics. Currently anyway.

I'm just wondering why we're seeing claims of over 300 Wh/kg. In fact I'm yet to see more than 260 Wh/kg in real life from any cell...

Maybe its typical ebike hype
Saw an ad for 150km range in classifieds last night, yet seller has no clue what Ah is. Copy & Paste from china seller no doubt.

There is one 18650 I saw on nkon site 3 or 4 months ago, claiming 4Ah, further investigation revealed it was 3.75 or something, and not really that good compared to other choices.

jonescg said:

claims of over 300 Wh/kg. In fact I'm yet to see more than 260 Wh/kg in real life from any cell...

Click to expand...

Some time back i asked on the "Battery Technology/new info, " thread , if anyone was aware of any commercially available lithium cell with an Energy Density higher than 250 -280 Whkg (750 Wh\ltr)..
So far no positive sightings !!
There are many other performance parameters that have improved (cycle life , etc) , but Energy density seems to have topped out for the past 8-9 years.