SoftBank to Manufacture Large-Scale Batteries for AI Data Centres at Former Sharp Plant
May 11, 2026 – 7:21 am
Image by: AFP/Getty Images
Target output is one gigawatt-hour a year. Partners are South Korea’s Cosmos Lab and DeltaX. Production opens for the fiscal year starting next April, with zinc-halide chemistry following in 2027.
SoftBank Group’s mobile-services subsidiary will begin manufacturing large-scale battery cells at the Sakai, Osaka site that once belonged to Sharp, the company said on Sunday, targeting roughly one gigawatt-hour per year of output once the line is at scale.
The plant supplies storage for the AI data centres SoftBank is already building, and for grid, industrial, and residential customers beyond that.
Conversion Details
The conversion has been signalled since April, when SoftBank confirmed that the 440,000-square-metre former LCD factory it bought for about ¥100 billion would house Japan’s largest battery production line.
The Sunday disclosure sharpens the timeline. Mass production begins in the fiscal year starting April 2026, in partnership with two South Korean firms:
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Cosmos Lab, which contributes zinc-halide cell chemistry,
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DeltaX, which contributes systems integration.
Zinc-halide manufacturing is targeted for 2027, with lithium-iron-phosphate and other chemistries supplying earlier volumes.
Economic Logic
The economic logic is the same one that drove the Sharp acquisition:
- AI data centres need large, fast-discharge storage to smooth power demand and survive grid events;
- The lithium-iron-phosphate and zinc-halide combinations SoftBank is building are well suited to that profile and avoid the rare-earth and cobalt supply chains that have come under Chinese export-control pressure.
- Zinc-halide in particular is non-flammable and uses widely available materials, which matters for data-centre fire-code approval and for siting batteries inside or near server halls.
Japanese Industrial Reuse
The Sakai conversion is one of the more concrete examples of Japanese industrial reuse: a high-volume display factory built for a category that lost out to OLED, now repurposed for the storage category AI has made urgent.
The economics of that reuse only work if utilisation runs high, which is why SoftBank has chosen to vertically integrate. The company is both the data-centre operator and the battery customer.
Global Storage Capacity Shortage
The $1.4 trillion of utility capex US grids are spending to keep pace with AI demand is testimony to that pressure, and the wave of energy-storage startups already chasing that demand has so far produced more demos than deployable gigawatt-hours.
SoftBank is betting that owning manufacturing, rather than buying cells, gives it both control over delivery schedules and a margin on units it does not consume internally.
The partner choice tells its own story. Both Cosmos Lab and DeltaX are South Korean, which positions the joint venture inside the South Korean battery-tech ecosystem rather than the Chinese one. That has commercial and policy advantages.