Large cylindrical energy storage system

Large cylindrical batteries feature a steel casing with 550MPa strength—5.5 times that of prismatic aluminum casings (95MPa). Combined with a 1500MPa dual-layer hot-formed steel bottom design and 3500MPa aerospace-grade fiberglass, they achieve crash energy absorption of 1000J—6.6 times the national standard.

The ability to thermally manage cylindrical cells limits their maximum size. Surface to volume ratio and inner structure are critical to cell performance. Large cylindrical cells must be base cooled and have continuous tabs. For small cylindrical cells side cooling is most efficient.

Here, we can see that the manufacturing efficiency of large cylindrical batteries at 300 PPM is 10 times that of prismatic cells, while our manufacturing steps have been further reduced to 10 steps, shortening the production cycle to 7 days.

The circular geometry of large cylindrical batteries ensures uniform stress distribution from the beginning to the end of their lifecycle, eliminating axial swelling entirely.

As an example, we demonstrate that the best cooling approach for the 4680 tabless cell is base cooling, while for the 2170 LG M50T cell it is side cooling. We conclude that any viable large format cylindrical cell must include a continuous tab (or 'tabless') design and be cooled through its base when in a pack.

A cylindrical cell is composed of a jellyroll (current collector, electrodes, separator soaked), internal tabs and the outside metal can filled with electrolyte. Fig. 1 shows the schematic description of cylindrical cells with single and continuous tab (or tabless).