Samsung SDI develops shorter cylindrical cells
According to Korean media, Samsung SDI is not only developing 4680-format battery cells for Tesla but also shorter cells with the same diameter for other car manufacturers. One potential customer is probably from Germany.
The Korean publication The Elec, writes that Samsung SDI is not only testing battery cells in the format requested by Tesla with a diameter of 46 mm and a height of 80 mm but also other variants that also have a diameter of 46 mm but a height of between 40 and 60 mm. The South Korean company’s development of 4680 cells became clear in July of 2021.
According to this latest report, Samsung SDI wants to offer shorter variants to BMW, Volvo and Stellantis. For example, two battery cells each with a diameter of 46 mm and a length of 40 mm (i.e. a 4640 cell) could be stacked on top of each other, creating a battery pack with two layers.
The shorter variants are not only to be developed in order to give carmakers further options in the design of modules and packs but also to reduce production problems.
For example, the “jelly roll” process (i.e. rolling up the cathode, anode and separator foil) is more difficult with long round cells, and the length can probably also lead to difficulties in filling the electrolyte. In another example, protruding tabs in the cylindrical cells must be folded in, requiring special production equipment.
A longer battery also means that electrolytes can more easily leak out when they are injected. Here, the area between the can and the cap must also be cleaned, so Samsung SDI is planning to use etching laser technology for this purpose.
In May, Bloomberg reported that BMW could switch to round cells for the new class – until now, the carmaker has relied on prismatic cells. As Bloomberg wrote, the new cells are to be manufactured by existing BMW suppliers and Samsung SDI is known to be one of them. BMW’s new round cells are said to exceed the energy density of Tesla’s cells by “at least a double-digit percentage”. Which round cell format the German automaker favours, however, was not mentioned.
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