SoftBank of Japan is moving into next-generation batteries that do not rely on rare metals, partnering with South Korean deep-tech startup Cosmos Lab, founded in 2021.
The Nikkei business daily reported on Monday that SoftBank and Cosmos Lab plan to jointly develop a “zinc-halogen battery” and begin mass production during fiscal 2027. The production base will be set up at the Sakai plant site in Osaka once owned by Sharp, which SoftBank acquired in 2025.
Nikkei said SoftBank plans to include entry into next-generation battery manufacturing in a new medium-term management plan to be announced in May, with a long-term goal of building the business into a new pillar generating annual sales of 100 billion yen (about 9.2 trillion won).
The new battery uses zinc for the anode and a halogen compound for the cathode, instead of rare metals such as lithium and cobalt. Nikkei said both materials are easy to procure in Japan, improving cost competitiveness. A key advantage is that the electrolyte uses water rather than an organic solvent, making the risk of ignition “almost nonexistent in principle,” the report said, a potential differentiator as safety concerns have grown after a series of energy storage system fires.
Zinc-based batteries, however, typically have a shorter lifespan than lithium-ion batteries. During charging and discharging, dendrites can form on the electrode surface, accelerating degradation. Nikkei reported that Cosmos Lab improved this limitation with a proprietary technique that suppresses crystal formation by creating microscopic holes in the electrode. Further development to raise energy density is also planned.
SoftBank plans to first apply the batteries to a large data center it is building in Sakai to verify performance, and then decide whether to proceed with full-scale mass production. It also aims to expand use to factory and home energy storage systems and renewable energy storage.
Nikkei said SoftBank is considering investing several tens of billions of yen by 2030 to expand production capacity to more than 1 gigawatt-hour. That would be enough to produce more than 100,000 home energy storage units a year and would make it Japan’s largest plant, the report said.
Cosmos Lab, based in Siheung, Gyeonggi Province, has been developing “water battery” technology using water-based electrolytes, which is seen as a way to improve safety while reducing dependence on rare metals.
SoftBank has tested next-generation batteries through development of high-altitude platform stations, or HAPS, unmanned aircraft that provide communications links with the ground. In 2021, it also built a next-generation battery evaluation and verification facility in Tochigi Prefecture. Nikkei said the partnership with Cosmos Lab signals a push toward commercialization that also envisions supplying batteries outside the company.
The report linked the move to Japan’s “sovereign AI” strategy. SoftBank has promoted domestic production of “technologies that support AI operations,” including AI semiconductors and next-generation communications base stations. Nikkei said the effort also reflects a push to secure data center energy storage systems through supply chains in Japan and allied countries, while reducing reliance on China, which holds a dominant share in rare-metal mining and refining.
Zinc-based batteries are also being pursued in Japan by manufacturers such as FDK and by universities including Hokkaido University and Tohoku University. Nikkei said SoftBank’s decision to work with a new Korean startup highlights intensifying competition for technological leadership in the next-generation energy storage market.
* This article has been translated by AI.
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