Background to the adoption of all-solid-state batteries

SeoIn 2021, Maxell announced a high-output coin type all-solid-state battery that offers long life, high safety, and the ability to operate across a wide range of temperature environments. Following this release, we were approached by SUBARU.

TsuchiyaSUBARU was planning to build a new vehicle plant on a 600,000 ㎡ site adjacent to our Oizumi Plant in Gunma Prefecture. In exploring options to make this a smart factory, we became interested in Maxell's all-solid-state batteries. Currently, many backup batteries are used in the plant for FA robots and other equipment, but, because they are primary batteries, they reach the end of their life in about one year and must be discarded. By using all-solid-state batteries, the lifespan can be extended to around 10 years, which significantly reduces waste and greatly contributes to conserving the environment and reducing replacement work.

JinWe are replacing the ER (lithium thionyl chloride) batteries currently used for backup power in the existing FA robots with SBMs. Demonstration testing was conducted at SUBARU’s plant, and in August 2025, we successfully completed testing with the final SBM specifications installed. We will now begin considering mass production of SBMs at Maxell.

Evaluation of all-solid-state batteries

TsuchiyaWinters at the plant in Gunma Prefecture can be cold, with temperatures dropping to between -10°C and -15°C. On the other hand, some of our manufacturing processes reach temperatures as high as 120°C. Therefore, the all- solid-state batteries are being tuned to suit this demanding operating environment.

SeoTo create a product that meets SUBARU’s required specifications, we have repeatedly gone through a process of design, evaluation, and verification, overcoming a variety of challenges. The environment in which the batteries will be used proved to be far harsher than we expected, but over the course of about two years we have been proceeding according to plan, from the initial proof-of-concept prototype to the performance prototype, and now to the mass-production prototype.

JinThe greatest challenge was to miniaturize the SBM so that it could be installed in the limited space available in existing robots, while still ensuring performance, reliability, and safety under harsh conditions. The FA robot manufacturer has adapted the robots so that charging power can be supplied from the completed SBM.

TsuchiyaThe specifications match our requirements. Once again, batteries that do not burn are truly groundbreaking. They will contribute to improving safety in the factory, and I believe they are a product that will also make broad contributions to people’s lives.

OhbaI am also looking forward to future improvements in recyclability.

JinMaxell’s all-solid-state batteries are made only of metal and ceramic, so they have very high recyclability. Additionally, because there is no risk of combustion, packaging and transportation can be made more efficient, which also leads to reduced logistics costs. The challenge will be to create a system for collection through to reuse.

Expectations for Maxell going forward

TsuchiyaAn automobile plant encompasses a variety of processes such as painting, assembly, and welding, each of which is as large-scale as what one might envision for an entire company. Therefore, in the future of automobile manufacturing, it will be essential to connect these processes, each of which tends to become siloed, through DX under a unified concept. In order to collect and utilize detailed information as data, there will be an even greater need for compact batteries that can be used in a wide range of environments.
 I hope Maxell will further deepen and develop its unparalleled ability to propose solutions tailored to customers, so that we can grow together. For example, if all-solid-state batteries are made larger in the future, then their range of applications could be expanded even further to include Automated Guided Vehicles (AGVs) and Autonomous Mobile Robots (AMRs).

SeoRegarding larger formats, we would like to identify areas within SUBARU where all-solid-state batteries can demonstrate their advantages and work toward them within the scope of Maxell’s strengths. In addition, we will continue making proposals that address SUBARU’s specific needs, such as applications that combine batteries with sensors.
 By being seconded to SUBARU, I have been able to experience its design philosophy and approach to manufacturing, and I have once again realized the depth of “thinking about the customer’s challenges together.” If we can understand not just what the challenges are, but also how they are affecting operations, then we can make proposals that enhance strengths of SUBARU. Also, in being involved with initiatives for DX at the new plant, I have noticed a commonality with Maxell in that SUBARU also places people at the center of its thinking.

Ohba I also work at the plant, and I believe that promoting DX should not be driven solely by digital technology, but rather by how we can improve operations to be better and more people-friendly. From the perspective of leveraging the know- how accumulated by people, we aim to enhance the value of the plant. While some may call this approach unrefined, that is precisely our strength.

TsuchiyaDX is merely a means, and our shared perspective with Maxell is in keeping people at the center. Through technical, organizational, and human collaboration that transcends corporate boundaries, we aim to create value for society while also helping to raise the overall level of manufacturing in Japan.