According to more and more media reports, General Motors is expected to announce a new EV battery-related partnership with Samsung SDI.

The articles, based on unofficial sources, say that the two companies might sign a Memorandum of Understanding (MOU) this week (on Wednesday, March 8).

The reports build on the previous news that GM-LG Energy Solution (LGES)'s talks about the fourth battery plant in the United States stalled. GM and LGES have so far launched three Ultium Cells battery projects (the first plant is already producing battery cells, since 2022).

The plants with LGES were focused on a pouch battery form factor, while another rumor was that GM is considering also using (for the very first time) cylindrical battery cells.

As we understand, the reason to add an additional EV battery partner would be to use some kind of new, cylindrical batteries that the existing battery partner is not willing to supply (at least up to specs/time/cost requirements).

Here is where Samsung SDI comes into play. The South Korean manufacturer was supplying mostly prismatic battery cells and smaller capacity cylindrical cells (1865- or 2170-type), which LGES also has in its offer. However, Samsung SDI is also pursuing the higher-capacity 46xx-type cylindrical battery cells (a standard diameter of 46 millimeters).

Unofficial reports suggest that the GM-Samsung SDI deal will result in a joint venture factory located in Michigan, which might have an annual manufacturing capacity of 30-50 gigawatt-hours (GWh) of battery cells (enough for 300,000-500,000 BEVs, assuming 100 kWh/car). Such a factory would cost at least a few billion.

It will be very interesting to see whether the switch will also require the development of an all-new EV platform, or if the Ultium platform is flexible enough to accommodate the new type of cells/modules or even cell-to-pack design.

GM CEO Mary Barra said that “One of the strengths of the GM platform is the ability to use pouch, prismatic and cylindrical battery cells,” which is another sign that cylindrical battery cell rumors might be true.

By the way, Tesla is also using various battery form factors (and chemistries), starting with 1865-, 2170-, 4680- and prismatic (LFP), not even dropping the earliest 1865-type.

A joint venture with GM would be a big boost for Samsung SDI, which so far was a much smaller EV battery supplier than LGES and later also SK Innovation's SK On. The company is also building a battery factory in Indiana, together with Stellantis, as well as expanding its battery pack facility in Michigan.

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