General Motors has agreed to sell its entire 49.99% stake in the Synergy Cells joint venture with Samsung SDI, handing over the under-construction battery cell plant in New Carlisle, Indiana, to the Korean battery maker. The deal, announced on August 11, 2026, marks the second time in less than two years that GM has exited a planned cell factory, according to the Chinese business outlet Huxiu.
In December 2024, GM sold its stake in the yet-to-open Lansing, Michigan, plant to LG Energy Solution. Now it is stepping back from the New Carlisle project, which was announced in 2023 and formalized in 2024 with a planned investment of about $3.5 billion. The facility was designed for an annual capacity of 27 GWh, expandable to 36 GWh, mainly producing high-nickel cells.
While shrinking its dedicated cell capacity, GM is doubling down on next-generation battery research. Near its global technical center, the Wallace Battery Cell Innovation Center is already operating, and the Ancker-Johnson Battery Cell Development Center is under construction. Together, these facilities represent an investment of nearly $900 million, according to Auto Business Review, cited by Huxiu. The Wallace center focuses on materials, chemistry, cell formats, and large-scale prototypes, while the Ancker-Johnson center will handle design and manufacturing validation closer to production scale. GM expects the latter to cut new battery development time by up to one year.
From customer to co-definer
GM's strategy appears contradictory: selling plant stakes while investing in R&D and retaining exclusive manufacturing rights for new cell types. In 2026, GM partnered with U.S. energy storage firm Peak Energy to develop sodium-ion cells, with GM handling cell development and keeping manufacturing rights, while Peak Energy integrates the cells into grid and data-center storage systems.
The approach reflects a shift from owning capacity to controlling technology. GM cannot develop and mass-produce next-generation cells without partners like LG Energy Solution and Samsung SDI, but it wants to influence the chemistry, cell format, performance targets, and manufacturing processes earlier. It aims to become a co-definer of future cells rather than just a buyer, transferring capacity risk while retaining technology involvement.
GM's battery history predates the Ultium system. Its Brownstown, Michigan, plant began producing battery packs for the Chevrolet Volt in early 2010, with cells supplied by LG Chem (now LG Energy Solution). Today, Brownstown still makes battery packs for the Corvette E-Ray and Cadillac CELESTIQ, along with some prototype work.
Selective holding
The divestments are driven by capacity utilization. Cell manufacturing is a capital-intensive business with high fixed costs, and production lines are tailored to specific cell formats and chemistries, making them hard to repurpose quickly. In January 2026, the Warren, Ohio, Ultium Cells plant suspended production, idling about 850 workers for nearly seven months until August.
After the two sales, GM still holds stakes in the operating Ultium Cells plants in Warren, Ohio, and Spring Hill, Tennessee, and continues to run the Brownstown pack plant. The Lansing plant, now fully owned by LG Energy Solution, started production in August 2026, serving customers including Toyota electric vehicles and also handling energy storage batteries. The New Carlisle site, which halted equipment installation in May 2026, will become Samsung SDI's first independently operated battery plant in North America, initially producing energy storage batteries. Samsung SDI and GM have also signed a joint development agreement for next-generation prismatic cells, which could be produced at the plant, though the chemistry has not been disclosed.
