The number investors could not ignore

LG Energy Solution's second-quarter operating profit fell 77% year over year to just 113.3 billion won, even as revenue climbed 25% to 7.56 trillion won 1. The gap between those two numbers is the story: demand held up, but the mix underneath it did not. North American EV sales stayed weak, idled joint-venture lines kept weighing on utilization, and a bottleneck in pack assembly slowed the one business segment that was supposed to cushion the fall — energy storage systems, or ESS 2. Strip out a 241 billion won US manufacturing tax credit, and the quarter was actually an operating loss 1.

That combination — EV demand cooling, ESS scaling faster than the supply chain can absorb — is now the defining tension for all three of Korea's battery majors, and it is forcing them into visibly different bets rather than a single shared playbook.

Three companies, three answers to the same problem

LG Energy Solution is doubling down on expansion: it began mass-producing lithium-iron-phosphate cells for ESS at its Ultium Cells joint venture in the US in July, and once a Michigan plant comes online later this year the company will control more than 50 gigawatt-hours of North American ESS capacity 3. Samsung SDI has taken the opposite approach, prioritizing high-margin supply over sheer volume, and it is already winning the marquee contracts that prove the strategy out 3. SK On, the smallest and most financially strained of the three, is projected to post roughly 288.3 billion won in second-quarter operating losses and around 1.06 trillion won for the full year, but it is converting EV lines toward battery energy storage supply deals in the US and Korea to narrow the gap 8.

From EV plants to AI power plants

The reason all three are chasing the same pivot is demand, not desperation alone: AI data centers need grid-scale power buffering, and that need is arriving faster than new US EV subsidies are being written. LG Energy Solution has signed a roughly 2.4 trillion won supply deal to provide batteries for OpenAI-linked data-center capacity, a contract explicitly aimed at the North American LFP storage market rather than vehicles 5. Samsung SDI has landed its own roughly 1.5 trillion won ESS deal and, more tellingly, captured about 66% of South Korea's first AI-linked grid ESS project domestically — a home-market vote of confidence that its battery-backup-unit-focused strategy is working 4. Seoul's Ministry of Climate, Energy and Environment has reinforced the shift with a state-backed AI-powered ESS deployment program that named LG Energy Solution among its operating consortiums, effectively subsidizing the same transition the market is already pricing in 3.

The Stellantis retreat makes the pivot literal

Nowhere is the reallocation more concrete than in Kokomo, Indiana, where Samsung SDI and Stellantis are moving to unwind their StarPlus Energy joint venture after Stellantis booked more than 22 billion euros in EV-related writedowns 7. Rather than simply mothball the asset, Samsung SDI is converting existing lines at the site to produce prismatic LFP cells for stationary storage — turning a stranded EV investment into ESS capacity without waiting for a new greenfield build 7. That is the clearest evidence yet that this is not a side project bolted onto EV manufacturing; it is becoming the primary use for capacity that EV demand can no longer fill.

A three-way battle is about to get a scoreboard

The next real test lands in September, when South Korea runs a roughly 672 million dollar ESS procurement auction that all three domestic makers are expected to contest directly, alongside a second national ESS tender SK On has already partly won 6. Auctions like this matter because they are transparent: unlike opaque US data-center contracts, they will show, in publicly disclosed won-per-kilowatt-hour terms, which of the three companies' post-EV strategies the market actually prices as cheapest and most bankable.

What it means for investors

The read-through is that Korea's battery sector is no longer a single EV-demand trade — it is splitting into a storage-capacity land grab where balance-sheet flexibility (LG Energy Solution's scale), contract-winning credibility (Samsung SDI's early domestic share), and cost discipline under losses (SK On) will separate winners well before global EV sales recover. Analysts already cut LG Energy Solution's near-term targets on the Q2 miss even as they raised longer-run ESS forecasts for the second half 2, which is the market's way of saying the transition is real but not yet smooth. Investors watching this sector should treat September's auction results, not the next EV sales print, as the more informative signal for 2026.