Idemitsu Kosan Co., Ltd. has announced its decision to construct a large-scale production facility for lithium sulfide (Li2S), a crucial intermediate raw material for solid electrolytes used in next-generation all-solid-state lithium-ion batteries. This strategic move underscores Idemitsu's commitment to establishing an integrated value chain and accelerating the commercialization of all-solid-state batteries by 2027-2028.

The planned Li2S large-scale facility will be located within the company's Chiba Complex in Ichihara City, Chiba Prefecture, with construction slated for completion in June 2027. This initiative, recognized by the Ministry of Economy, Trade and Industry (METI) as a "plan for ensuring supply of storage batteries," will receive a maximum grant of approximately 7.1 billion yen out of the total project cost of roughly 21.3 billion yen.

Idemitsu aims to achieve world-leading production capacity of lithium sulfide, equivalent to 3 GWh/year of storage batteries, thereby securing a stable supply of this critical material. The company's strategy involves leveraging its long-standing expertise in handling sulfur components, a byproduct of petroleum refining, to produce high-purity lithium sulfide.

"The mass production of lithium sulfide is a major step toward achieving our goal of commercializing solid electrolytes," stated a company spokesperson. "By improving the performance of solid electrolytes and accelerating the development of mass production technologies, and steadily building a value chain, we aim to contribute to the social implementation of all-solid-state batteries, which are considered the mainstay of next-generation batteries."

All-solid-state batteries offer significant advantages over conventional liquid electrolyte batteries, including faster ion movement, reduced charging times, increased power output, and enhanced safety due to their resistance to high voltage and temperature. These characteristics are expected to drive the adoption of all-solid-state batteries in electric vehicles (EVs) and other energy storage applications.

Idemitsu has been actively developing solid electrolyte technology and establishing a mass production system. The company currently operates two small-scale verification facilities and initiated the basic design of a large pilot facility in October 2024. The construction of the Li2S large-scale facility is a critical step in scaling up production and meeting the growing demand for high-performance solid electrolytes.

The company's integrated value chain encompasses the sourcing of sulfur components from its petroleum refining processes, the production of lithium sulfide, and the manufacturing of solid electrolytes. This comprehensive approach ensures a reliable and efficient supply of materials, strengthening Idemitsu's position in the emerging all-solid-state battery market.

By contributing to the government's policy of strengthening the storage battery supply chain and improving the competitiveness of Japan's storage battery industry, Idemitsu is playing a pivotal role in the advancement of next-generation battery technology.