SK On says robot solid-state batteries face 4x cost test

SK On says solid-state batteries could give industrial robots 8+ hours of runtime — enough to cover a human work shift — but the company is also acknowledging the obvious problem: cost.

Speaking at the 2nd Battery Foundry Forum in Seoul on July 15, 2026, Ko Young-seok, executive vice president and head of product planning at SK On, argued that adoption will depend less on headline battery tech and more on total cost of ownership. The alternative options are cheaper today: battery swapping and ultra-fast charging.

That matters because current lithium-ion robot batteries typically power machines for just one to two hours per charge, according to the report. But they are also cheap. SK On says a Li-ion battery currently accounts for under 2% of an industrial robot’s manufacturing cost, while a switch to solid-state would push that share to roughly 8% — a 4x jump.

SK On’s pitch is that the math may still work for industrial users. A longer-lasting battery could reduce the need for spare packs, charging time, battery swaps, and even extra robots kept on hand to cover downtime.

For context, the report cites a widely shared teardown of Tesla Optimus Gen 2 that puts the battery pack at about $300 in a roughly $55,000 hardware cost structure, or around 0.5% of the bill of materials. It also notes that some independent estimates, including McKinsey’s, place battery modules at 5–10% of a humanoid robot’s bill of materials.

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SK On has already built its all-solid-state pilot plant at its Future Technology Institute in Daejeon, completed last September in partnership with US solid-electrolyte company Solid Power. The company is developing:

• a polymer-oxide composite cell for commercialization in 2028
• a sulfide-based cell in 2029

SK On says that roadmap has already been accelerated by one year. Rival Samsung SDI, also working with Solid Power, is targeting 2027.

That could make robotics a more realistic early market for solid-state batteries than EVs. For robots with short duty cycles, cheap Li-ion packs plus swapping or fast charging may remain the better choice. But for industrial buyers that need sustained operation and can absorb the premium, SK On is betting the TCO case will be enough.