MarcG
Active Member
Both I believe. The larger cell has more active material in relation to both the exterior casing and the void left in the center from the forming mandrel.
According to the CleanTechnica article below, the 2170 cells that Tesla uses in the Model 3 has slightly more energy density by weight (247 Wh/kg) than the 18650 found in the S & X (240 Wh/kg).
Tesla Model 3 Battery Pack & Battery Cell Teardown Highlights Performance Improvements | CleanTechnica
In the linked video, the speaker Jack Rickard mentions the energy density by volume is even much better at the pack level: 159.5 Wh/kg for the 3 versus 126.7 Wh/kg for the S/X. Even more impressive given the Model 3 pack includes the junction box, AC charger, and DC/DC converter, whereas these are external to the Model S/X packs.
As far as energy density by volume is concerned, Jack didn’t compute these numbers in his video, but he does provide the inputs to the equation at the cell level:
The 2170 cell is 970 cubic mm for 17.3 Wh, which equates to 0.0178 Wh/mm^3.
The 18650 cell is 660 cubic mm for 10.8 Wh, which equates to 0.0164 Wh/mm^3.
So, it appears the 2170 cell used in the Model 3 is also more energy dense by volume than the 21650 cell uses in S/X.
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