SEOUL, Oct 22 (Reuters) - South Korea"s Samsung SDI Co Ltd (006400.KS) said on Friday that it had entered an agreement for a joint venture with automaker Stellantis NV (STLA.MI) to produce electric vehicle (EV) battery cells and modules in the United States. It aims to start the plant by the first half of 2025 with an initial annual battery production capacity of 23 gigawatt hours (GWh), the South Korean battery maker said in a statement. The joint venture"s annual battery production capacity could increase to 40 GWh in the future, which could power about 670,000 electric vehicles, Samsung SDI added. No financial details of the deal were provided. The batteries produced at the U.S. joint venture will be supplied to Stellantis" factories in the United States, Canada and Mexico. The location of the factory is under review. Samsung SDI, an affiliate of South Korean tech giant Samsung Electronics (005930.KS), already has EV battery plants in South Korea, China and Hungary, which supply customers such as BMW (BMWG.DE) and Ford Motor (F.N). The Stellantis-Samsung SDI tie-up comes less than a week after the world"s No. 4 automaker signed a battery joint venture agreement with South Korea"s LG Energy Solution. Stellantis, formed in January from the merger of Italian-American automaker Fiat Chrysler and France"s PSA, has said it wants to secure more than 130 GWh of global battery capacity by 2025 and more than 260 GWh by 2030.