Samsung SDI buys out GM’s stake in the Indiana battery plant, which will make ESS cells

Samsung SDI has acquired the 49.99% stake General Motors held in SynergyCells, the battery joint venture the two companies established in New Carlisle, Indiana. Samsung SDI describes the plant as its first independently operated battery production base in North America.

The two also signed a new joint development agreement covering prismatic cells for potential future EV applications.

The ownership change reflects market changes since the joint venture was announced, including slower-than-expected growth in EV demand, according to Samsung SDI. The two partners have decided to seek forms of cooperation other than the joint venture.

The plant is under construction. Samsung SDI will start by building cells for energy storage systems (ESS) rather than EVs, a decision it attributes to demand in the US storage market. Prismatic cells developed jointly with GM could be produced there later.

Prismatic cells pack into a module with less wasted volume than cylindrical cells, and their rigid cans need less external support than pouch cells. Cells built for stationary storage are optimized differently from EV cells, weighting cycle life and cost per kilowatt-hour above specific energy.

Samsung SDI signed a three-year contract in December 2025 to supply prismatic LFP cells for energy storage systems in North America starting in 2027, a deal valued at more than 2 trillion won ($1.35 billion).

GM and Samsung SDI finalized the joint venture in August 2024, committing about $3.5 billion to a plant that was to begin production in 2027. Initial annual capacity was set at 27 GWh, expandable to 36 GWh, and the joint venture was to build nickel-rich NCA prismatic cells.

“While reflecting recent market changes, this acquisition decision is to continue the strategic partnership with GM,” said a Samsung SDI official.

Source: Samsung SDI