Tesla introduced the world to the 4680 battery cell. With 46 millimeters in diameter and 80 millimeters long, it should be not more ultra batteries – the perfect size to get the most out of an EV battery pack. But Samsung SDI has other ideas. It works on 4680 battery cells for Tesla, which is the biggest game in town, but it also tries shorter versions of the “fat cells” it hopes to give to other manufacturers like Volvo, BMW and Stellantis.
According to Korean news source The Elec, manufacturers were able to stack two levels of 4640 cells on top of each other to create a two-level battery pack. Although that arrangement may be somewhat heavier and cost more than a single layer of 4680 cells, it may provide benefits such as better control of the battery cell temperatures in the battery pack. The 4660 cells would allow a manufacturer to have a somewhat lower floor height in a finished car.
There are interesting ideas, but that Electric points out that the primary reason for these shorter cells is better control over production quality. The longer the cell, the more difficult it is to adjust all the components inside – the cathode, anode and separator foil – accurately. In addition, protruding flaps must be folded into the cylindrical cells, which requires specialized production equipment.
The extra length can also lead to difficulties in injecting the electrolyte that sits between these components correctly. A longer battery means that electrolytes can leak out when injected, which means that the area between the can and the lid must be cleaned. Samsung SDI plans to use etching laser technology for that purpose.
In May, Bloomberg reported that BMW is considering switching to round cells for new electric car models instead of the prismatic cells it now uses. The round cells are to be manufactured by existing BMW suppliers and Samsung SDI is known to be one of these suppliers. BMW’s new round cells are said to exceed the energy density of Tesla’s cells by “at least a double-digit percentage.” Electric reports. At present, there is no official word on which manufacturers are interested in using the shorter cells with a diameter of 46 millimeters.
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