Samsung SDI’s home town of Ulsan, on Korea’s southeastern coast, is where the company’s battery story began, and the company now wants it to be where the next generation is built. The battery maker said Thursday it plans to invest nearly 16 trillion won, about $10.4 billion, in Ulsan between 2026 and 2040 to produce next-generation batteries, with the money aimed at solid-state cells, lithium-iron-phosphate chemistry and sodium batteries.
The plan, disclosed in a regulatory filing, is one of the largest industrial commitments announced by a Korean battery company in years. Samsung SDI said the investment size and timetable could be adjusted depending on market conditions, language that gives the company room to slow down or accelerate as demand moves.
The three chemistries in the plan point in different commercial directions. Solid-state batteries promise higher energy density and better safety, and automakers see them as the technology that will finally make electric vehicles competitive with gasoline cars on range and charging time. LFP cells, the chemistry that Chinese manufacturers have turned into the industry standard for affordable EVs, are cheaper and more stable than the nickel-based cells Samsung SDI has traditionally sold. Sodium batteries are the cheapest of the three and are aimed at stationary storage and entry-level vehicles where energy density matters less than cost.
Samsung SDI has talked about each technology for years, and the filing converts those statements into a capital plan. The company has said it expects to begin mass production of solid-state batteries in the coming years, and it has been developing LFP cells specifically to compete with Chinese suppliers on price. Ulsan, its largest production site, gives it the factories, workers and port access the expansion requires.
Ulsan’s role in the plan is also a bet on Korean manufacturing competitiveness. The city already hosts Samsung SDI’s largest battery operations, and the company’s suppliers, from materials makers to equipment firms, have clustered around it over the past decade. Expanding there rather than in Hungary or the United States, where Samsung SDI has also built plants, keeps the most advanced production close to the company’s research base, a factor executives say matters for the speed of technology transfer.
The investment comes at a difficult moment for the industry. EV sales growth has slowed in key markets, battery prices have fallen sharply, and Chinese producers led by CATL and BYD have taken a majority of global capacity. Korean battery makers, including Samsung SDI, LG Energy Solution and SK On, have seen their market share shrink as automakers buy cheaper cells from China, and all three have responded by cutting costs and shifting toward premium chemistries where their technology still leads.
Solid-state is the technology Korean companies hope will restore their edge. The chemistry has been in development for more than a decade, and every major battery maker claims to be close to production, but none has shipped it at scale. Samsung SDI’s Ulsan plan bets that its work on the technology will translate into commercial volumes before rivals close the gap, a race that automakers are watching closely because solid-state cells could reshape vehicle design.
LFP and sodium round out a strategy of covering the market at every price point. Samsung SDI has acknowledged that it cannot ignore the low-cost segment, where Chinese competitors dominate, and its LFP plans are an attempt to compete there without abandoning the premium positioning its brand has carried. Sodium batteries, still early in their commercial life, give the company a hedge on future raw-material prices, since sodium is abundant where lithium is not.
The Ulsan focus also carries a political dimension. Korean policymakers have been pushing companies to anchor advanced manufacturing at home, and Samsung SDI’s filing follows a series of government-backed incentives for the battery and semiconductor industries. Investing in Ulsan, rather than in the overseas plants where Korean battery makers have expanded, signals that the company sees domestic production as part of its long-term competitiveness.
The timeline matters as much as the total. A 15-year investment horizon stretches across multiple product cycles, and the filing gives Samsung SDI flexibility to match spending to the pace of EV adoption. Analysts said the plan is better read as a statement of direction than a firm commitment, one that lets the company tell customers, workers and investors where it believes the industry is heading.
Samsung SDI’s announcement landed the same week the Korean government unveiled a broader push to keep advanced manufacturing in the country, and the two together underscore how seriously Seoul takes the battery race. The company did not say how the investment would be financed or what share of it would come from internal cash rather than debt, and the filing left those details for future disclosures.
For Ulsan, the plan is a vote of confidence in a city that has lived through the rise and fall of heavy industry. The battery factories of the 2030s, if the plan holds, will be built on the same waterfront where Samsung SDI has manufactured for decades. The question is whether the technologies the company is betting on arrive in time to justify the spending, and whether the market grows fast enough to absorb what Ulsan can produce.
