SoftBank’s mobile unit will produce large-scale battery cells at a repurposed Sharp factory in Sakai, Osaka, aiming to supply 1 gigawatt-hour annually starting fiscal 2026. Collaborating with South Korean partners, the effort supports AI data centers and wider energy storage needs.
- Repurposed Sharp factory targets 1 GWh/year battery output
- Uses lithium-iron-phosphate and zinc-halide chemistries
- Partners with South Korea’s Cosmos Lab and DeltaX
What happened
SoftBank's mobile-services subsidiary announced that it will start large-scale battery cell production at the Sakai, Osaka site previously owned by Sharp. Production begins in the fiscal year starting April 2026, focusing initially on lithium-iron-phosphate batteries, followed by zinc-halide cells from 2027. The plant aims for an annual output capacity of about one gigawatt-hour.
The project involves partnerships with South Korean firms Cosmos Lab, which specializes in zinc-halide chemistry, and DeltaX for systems integration. The facility conversion transforms the 440,000-square-meter former LCD manufacturing complex into Japan's largest battery production line, primarily to supply energy storage for SoftBank’s AI data centers and also grid, industrial, and residential customers.
Why it matters
SoftBank’s campaign addresses a critical shortfall in large-scale energy storage, driven by rising demand from AI data centers that require high-capacity, fast-discharge battery systems to stabilize power loads and maintain operations during grid disruptions. The use of lithium-iron-phosphate and zinc-halide chemistries avoids supply chain dependencies on rare-earth metals and cobalt, which face export control pressures from China.
The selection of zinc-halide batteries, in particular, offers safety advantages like non-flammability relevant to data center fire codes and siting requirements. By vertically integrating—both producing batteries and operating data centers—SoftBank can mitigate the multi-year lead times typical of large battery projects and maintain control over production schedules and costs.
What to watch next
SoftBank’s rollout timeline may experience delays, as energy storage manufacturing projects commonly face extended development periods. However, the company frames the Sakai plant as a strategic asset providing optionality rather than immediate scale dominance, given the relatively modest 1 GWh output compared to global leaders like China’s CATL.
Future developments to monitor include the successful implementation of zinc-halide battery production by 2027 and potential capacity expansions dependent on demand from AI infrastructure growth. Additionally, SoftBank’s South Korean partner relationships reinforce a supply chain strategy that avoids geopolitical and tariff risks associated with Chinese battery technologies.