Source: Getty Images
Idemitsu Kosan has received official approval from Japan’s Ministry of Economy, Trade and Industry to move forward with its plan
Tokyo-based Idemitsu Kosan Co. Ltd. plans to construct a large-scale production facility for solid electrolytes, a material that is used in all-solid-state lithium-ion rechargeable batteries, the company announced Feb. 27.
Disclosing its plans, Idemitsu said that it aims to expand the production capacity of lithium sulfide, which is an important intermediate raw material for producing solid electrolytes, to the tune of producing in capacity equivalent to 3 GWh per year of storage batteries. The planned production facility for solid electrolytes will help in establishing an integrated value chain, ranging from raw materials to intermediate materials and next-generation battery products in Japan.
With its planned electrolyte facility, Idemitsu said that it will work to meet the requirements of vehicle manufacturers as well as the battery manufacturers that are aiming to commercialize all-solid-state batteries in 2027–28. From there on, it would work to accelerate the commercialization of solid electrolytes.
It is known that developing a suitable solid electrolyte that provides high ionic conductivity, mechanical strength, ensures stability with electrodes, controls lithium dendrite formation and maintains consistent quality over time remains one of the key challenges in the mass production of all-solid-state batteries. This also contributes to a complex manufacturing process, making it difficult to scale up – a technical puzzle that several vehicle and battery manufacturers are working to solve globally.
Earlier in October 2023, Idemitsu Kosan had signed an agreement with Toyota Motor Corporation to jointly develop mass production technology of solid electrolytes with an intent of achieving mass production of all-solid-state batteries for battery electric vehicles (BEVs). Even as the partnership between Idemitsu and Toyota aims to improve productivity while establishing a reliable supply chain for solid-state batteries in Japan, the two companies had said that their collaboration seeks to ensure successful commercialization of all-solid-state batteries in 2027-28, followed by full-scale mass production. This plan is aligned with Toyota’s battery technology roadmap as disclosed at the Toyota Technical Workshop in June 2023.
Internally referred as the Li2S large-scale facility, Idemitsu said it would construct the electrolyte plant within the premises of its Chiba Complex in Ichihara City in Chiba Prefecture. The construction of this electrolyte plant is expected to be completed in June 2027.
According to the company, its plan of building a commercial scale plant for producing solid electrolytes has been approved by Japan’s Ministry of Economy, Trade and Industry. The ministry, it said, terms its bold proposal as a "plan for ensuring supply of storage batteries." The project is estimated to cost approximately ¥21.3 billion (about $141.38 million), of which the government is expected to approve ¥7.1 billion as the maximum grant amount.
Idemitsu plans to accelerate mass production of solid electrolytes with lithium sulfide produced by this facility as the base material and widely deliver high-performance solid electrolytes to various customers. “This will contribute to the government’s policy of strengthening the storage battery supply chain and improving the competitiveness of Japan’s storage battery industry,” the company said.
It is known that the all-solid-state batteries use a solid electrolyte, which allows ions to move faster. The solid-state battery chemistry is already understood to be offering a significantly increased power density, delivering a longer driving range, along with reduced charging time and superior power output when compared with the conventional liquid batteries. As a result, it is expected that electric vehicles equipped with all-solid-state batteries could address most of the long-standing concerns that consumers had when it comes to mass adoption of EVs.
In addition, the solid-state batteries are also resistant to high voltage and high temperature, thereby offering a longer service life.
Idemitsu said that it is operating two small-scale verification facilities for its advanced solid electrolytes at the site. The company said that it began working on the basic design of a large pilot facility in October 2024.
“The decision to construct an Li2S large-scale facility on this occasion was made because mass production of lithium sulfide, an intermediate raw material, is essential for the mass production of solid electrolytes in the future,” Idemitsu said, adding that lithium sulfide is an important intermediate raw material for its solid electrolytes, which are produced from sulfur components generated as a byproduct in the manufacturing process of petroleum products.
Copyright © 2025 S&P Global Inc. All rights reserved.
These materials, including any software, data, processing technology, index data, ratings, credit-related analysis, research, model, software or other application or output described herein, or any part thereof (collectively the “Property”) constitute the proprietary and confidential information of S&P Global Inc its affiliates (each and together “S&P Global”) and/or its third party provider licensors. S&P Global on behalf of itself and its third-party licensors reserves all rights in and to the Property. These materials have been prepared solely for information purposes based upon information generally available to the public and from sources believed to be reliable.
Any copying, reproduction, reverse-engineering, modification, distribution, transmission or disclosure of the Property, in any form or by any means, is strictly prohibited without the prior written consent of S&P Global. The Property shall not be used for any unauthorized or unlawful purposes. S&P Global’s opinions, statements, estimates, projections, quotes and credit-related and other analyses are statements of opinion as of the date they are expressed and not statements of fact or recommendations to purchase, hold, or sell any securities or to make any investment decisions, and do not address the suitability of any security, and there is no obligation on S&P Global to update the foregoing or any other element of the Property. S&P Global may provide index data. Direct investment in an index is not possible. Exposure to an asset class represented by an index is available through investable instruments based on that index. The Property and its composition and content are subject to change without notice.
THE PROPERTY IS PROVIDED ON AN “AS IS” BASIS. NEITHER S&P GLOBAL NOR ANY THIRD PARTY PROVIDERS (TOGETHER, “S&P GLOBAL PARTIES”) MAKE ANY WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, FREEDOM FROM BUGS, SOFTWARE ERRORS OR DEFECTS, THAT THE PROPERTY’S FUNCTIONING WILL BE UNINTERRUPTED OR THAT THE PROPERTY WILL OPERATE IN ANY SOFTWARE OR HARDWARE CONFIGURATION, NOR ANY WARRANTIES, EXPRESS OR IMPLIED, AS TO ITS ACCURACY, AVAILABILITY, COMPLETENESS OR TIMELINESS, OR TO THE RESULTS TO BE OBTAINED FROM THE USE OF THE PROPERTY. S&P GLOBAL PARTIES SHALL NOT IN ANY WAY BE LIABLE TO ANY RECIPIENT FOR ANY INACCURACIES, ERRORS OR OMISSIONS REGARDLESS OF THE CAUSE. Without limiting the foregoing, S&P Global Parties shall have no liability whatsoever to any recipient, whether in contract, in tort (including negligence), under warranty, under statute or otherwise, in respect of any loss or damage suffered by any recipient as a result of or in connection with the Property, or any course of action determined, by it or any third party, whether or not based on or relating to the Property. In no event shall S&P Global be liable to any party for any direct, indirect, incidental, exemplary, compensatory, punitive, special or consequential damages, costs, expenses, legal fees or losses (including without limitation lost income or lost profits and opportunity costs or losses caused by negligence) in connection with any use of the Property even if advised of the possibility of such damages. The Property should not be relied on and is not a substitute for the skill, judgment and experience of the user, its management, employees, advisors and/or clients when making investment and other business decisions.
The S&P Global logo is a registered trademark of S&P Global, and the trademarks of S&P Global used within this document or materials are protected by international laws. Any other names may be trademarks of their respective owners.
The inclusion of a link to an external website by S&P Global should not be understood to be an endorsement of that website or the website's owners (or their products/services). S&P Global is not responsible for either the content or output of external websites. S&P Global keeps certain activities of its divisions separate from each other in order to preserve the independence and objectivity of their respective activities. As a result, certain divisions of S&P Global may have information that is not available to other S&P Global divisions. S&P Global has established policies and procedures to maintain the confidentiality of certain nonpublic information received in connection with each analytical process. S&P Global may receive compensation for its ratings and certain analyses, normally from issuers or underwriters of securities or from obligors. S&P Global reserves the right to disseminate its opinions and analyses. S&P Global Ratings’ public ratings and analyses are made available on its sites, www.spglobal.com/ratings (free of charge) and www.capitaliq.com (subscription), and may be distributed through other means, including via S&P Global publications and third party redistributors.