Separator Tech Japan Co., Ltd. — 2026
We are replacing polyolefins with polyimide as the separator material. Our goal is to commercialize IOP, a microporous membrane separator that delivers heat resistance above 400°C, roughly twice the battery life, and high energy density at the same time.
* Heat resistance compared with PE. Battery life is an estimate under practical conditions. Cycle life is a projection for IOP combined with a high-temperature-resistant electrolyte. See "Validated Data" for test results.
With IOP (a polyimide microporous membrane separator), we aim to solve the challenges facing lithium-ion batteries.
Demand is surging for batteries that combine safety, long life, and high capacity, yet the separator—a core component of lithium-ion batteries—has remained a polyolefin material for 35 years. We are filling this technology gap.
* Heat resistance compared with PE. Battery life is an estimate under practical conditions. / Lithium-ion battery market size: Grand View Research (2022), USD 182.5B, converted at USD 1 = JPY 150.
For more than 35 years, polyethylene (PE) and polypropylene (PP) have been the main base materials for separators. Improving heat resistance and ion permeability is key to further raising battery safety, lifespan, and power output.
Current PE and PP separators melt at around 130–150°C. During abnormal heating, contact between the cathode and anode raises the risk of short circuits and fire. High temperatures also accelerate degradation and significantly shorten battery life.
Polyolefin manufacturing methods make it hard to raise porosity and significantly widen ion pathways. Limited ion permeability is one of the factors holding back faster charging and higher output.
Under high-temperature, high-load conditions, batteries degrade quickly, and some applications require frequent replacement. Replacement costs drive up operating expenses, creating demand for longer-lasting batteries.
Cell performance tends to drop in hot and cold environments, so stable operation requires materials designed for each operating environment. The separator–electrolyte combination determines the usable temperature range and performance.
Separator prices have fallen from about ¥200/m² to about ¥40/m². As price competition intensified, existing manufacturers prioritized cost cutting, making it hard to justify large investments in developing and mass-producing new materials.
Battery makers have focused their development investment on cathodes, anodes, and electrolytes, while separators have been procured on a "cost first" basis. As a result, improving performance through new separator materials has rarely been a development priority.
Using heat-resistant polyimide in battery separators requires technology to reliably produce high-porosity microporous membranes. Achieving mass producibility while maintaining performance has been the key challenge to commercialization.
IOP (a polyimide microporous membrane separator) aims to address the four challenges facing lithium-ion batteries through its high heat resistance and high porosity.
Solved by polyimide's heat resistanceWhile existing PE/PP separators melt at around 130–150°C, polyimide keeps its shape even above 400°C. It did not ignite in nail penetration tests under specific conditions, reducing the risk of short circuits caused by melting.
Solved by a high-permeability structureAt the same thickness as conventional separators, IOP has lower resistance, allowing more electrode material in the battery. Porosity of 55–70% improves ion flow by 1.5×, raising both capacity and output in the same battery size.
Solved by a degradation-resistant materialA life of 3,000 cycles is projected at 60°C. High porosity and uniform pore formation slow degradation even at high temperatures, reducing battery replacements and directly lowering operating costs. (*IOP combined with a high-temperature-resistant electrolyte)
Solved by wider electrolyte optionsPolyimide shows high wettability with high-temperature-resistant electrolytes and ionic liquids. It operates stably from −15°C to 85°C, and operation at 100°C has also been confirmed—allowing electrolytes to be matched to any environment, from hot regions to cold climates.
* All performance comparisons are relative to PE and based on in-house test data.
Measured and projected values for IOP compared with typical values for existing materials.
| Metric | IOP (Ours) | PE | PP | Ceramic-coated PP |
|---|---|---|---|---|
| Heat resistance | 400°C+ | Approx. 130°C | Approx. 135°C | 150–180°C |
| Porosity | 55–70% | 40–50% | 40–50% | 40–50% |
| Thickness | 7–20 μm (adjustable by application) | 8 μm+ | 8 μm+ | 12 μm+ |
| Ion permeability | 1.5× | Standard | Standard | Slightly lower |
| Cycle life | 3,000 cycles (60°C, projected)* | 1,500–2,000 cycles (room temp.) | 1,500–2,000 cycles (room temp.) | Slightly improved |
| Electrolyte options | Compatible with high-viscosity flame-retardant electrolytes | Limited | Limited | Limited |
| Safety (nail penetration) | No ignition* | Fire risk | Fire risk | Moderate |
* IOP values are in-house test data. PE, PP, and ceramic-coated PP values are typical figures based on public information.
* Cycle life conditions differ (PE/PP at room temperature; IOP projected at 60°C).
* Nail penetration results depend on test conditions.
Without waiting for solid-state batteries, IOP makes it possible to commercialize lithium-ion batteries that meet today's performance requirements.
| Metric | Solid-state batteries | IOP lithium-ion batteries |
|---|---|---|
| Mass production | △ Full-scale production and supply chains are still being built | ○ Can be produced on existing polyimide film lines (400°C heat-treatment line required) |
| Cycle life | ✗ Lifespan has improved, but interfacial degradation in large cells remains a challenge | ○ IOP + high-temperature-resistant electrolyte projected to reach 3,000 cycles at 60°C |
| Cost | ✗ Reducing material and new-process costs remains a challenge | ○ Uses existing production lines, enabling lower-cost mass production than solid-state |
| Time to market | △ Widespread adoption generally expected after 2030 | ○ Initial production planned for 2029, building a market track record before solid-state |
| Safety & temperature | ○ Excellent high-temperature tolerance; advanced safety and thermal management required | ○ Heat resistance above 400°C; discharge confirmed at −15°C and 100°C* |
| Development speed | ✗ Cells and manufacturing processes must be built from scratch | ○ Aims to shorten development by using existing cell designs and processes |
* Descriptions of solid-state batteries are based on company announcements and publicly available technology trends (as of August 2026).
* Cell tests at −15°C used a standard electrolyte; tests at 100°C used a high-temperature-resistant electrolyte.
We are validating measured results, and the life projections based on them, under each condition. Evaluation is ongoing.
Combining IOP with a high-temperature-resistant electrolyte is projected to deliver long life at 60°C. Conventional LIBs fall below 50% capacity after about 350 cycles.
3,000 cycles with 50% capacity retention (projected)With IOP and a high-temperature-resistant electrolyte, the cell functioned as a battery at 100°C. Current PP separators cannot discharge under these conditions.
100°C discharge performance confirmedSeparator change only (standard electrolyte). At −15°C, IOP delivered significantly higher discharge capacity than existing separators. Evaluation is ongoing.
−15°C discharge capacity maintainedUnder conditions in which current PP separators degrade rapidly after about 15 cycles, 95% capacity retention was confirmed after 200 cycles (0.1C). We are evaluating potential applications in high-energy-density uses.
95% capacity retention after 200 cycles* Source of experimental graphs: Tokyo Metropolitan University (2025 Battery Symposium in Japan). Stated values are results or projections under specific test conditions and do not guarantee performance in all operating environments.
Starting from proprietary know-how and patent filings, we are expanding our IP portfolio step by step.
* Foundational process patents are filed by Tokyo Metropolitan University, and we are in discussions to receive a license. Patent details are not disclosed at this time.
Electricity consumption is growing at a CAGR of about 15% and is expected to exceed the total power demand of Japan. As AI demand rises, backup power requires safe, long-lasting batteries.
With Japan targeting a 40–50% renewable energy share by FY2040, demand is growing sharply for grid storage that bridges supply-demand gaps. Long life, high output, and high safety are required to withstand frequent charging and discharging.
The shift to EVs is accelerating in major countries. As the market grows, batteries must combine safety under fast charging with a lifespan that resists degradation at high temperatures.
The drone market is expanding in logistics, defense, and inspection. High-energy-density, high-output batteries are needed, as they determine flight range and safety.
* UAV: unmanned aerial vehicles such as drones / UAM: urban air mobility using eVTOL aircraft, etc.
Sources: IEA, Energy and AI (2025) / Agency for Natural Resources and Energy, 7th Strategic Energy Plan (2025) / Grand View Research (2026) / MarketsandMarkets (2025–2026) / SNE Research
| Segment | Entry phase | Required performance | Why this market |
|---|---|---|---|
| Drones (large, industrial, etc.) | Early | Heat resistance at high output / stable current discharge / light weight | Battery performance directly determines product value |
| Power tools | Early | Instantaneous high current / fast-charge durability / longer life | Ongoing demand for battery replacement |
| Agricultural machinery | Early | Durability in hot outdoor environments / long continuous operation / vibration resistance | Early stage of electrification, with government subsidies |
| ESS (industrial & grid) | Next | Lower short-circuit risk from thermal shrinkage / high-temperature durability / long life | Fastest-growing market, driven by renewables |
| Data centers | Next | Less degradation on full-charge standby / high-current discharge / safety | Uptime is essential; reliability is the top priority |
| EVs (high-load) | Future | Fast-charging safety / less degradation in high-temperature storage / internal short-circuit prevention | Largest application, driving separator demand |
* Required performance reflects application hypotheses; IOP's improvement effects have not yet been verified.
* Separator market: Stratview Research (2024–2030) / Yen conversion: USD 1 = JPY 159.01 (as of August 26, 2026) / Subsidies for electric farm machinery: Ministry of the Environment, Ministry of Agriculture, Forestry and Fisheries
We translate performance differences in repeatedly used batteries into uptime and replacement costs, leading to early adoption.
① Temperature limits flight and back-to-back charging
② Repeated high-output flight and fast charging
③ Degradation and replacement raise operating costs
* Based on official specifications and SEC filings for major models from drone manufacturers.
① High heat resistance and temperature tolerance
Properties: keeps shape at 400°C / discharge confirmed from −15°C to 100°C
② Support for fast charging and high-load flight
Properties: 55–70% porosity / 1.5× ion permeability
③ Lower battery replacement and operating costs
Properties: 3,000-cycle life projected at 60°C
* Based on our own verification from IOP experiments, not on results in drones.
We evaluate jointly with battery and drone manufacturers, converting cell performance into uptime and operating costs.
→ Confirm performance and economic benefits, then decide on adoption and mass production
We supply the three early fields ourselves, and expand into volume markets through technology transfer and licensing.
→ To us: patent license (under discussion)
→ To partners: process technology transfer and licensing
→ To customers: supply of mass-produced products
Integrate IOP into cells and supply them for each application
We build three technology assets in-house, while using external facilities for large-scale production.
License (under discussion) and our own IP / evaluation data and criteria / manufacturing know-how
Production partners' facilities
We will scale up in three stages: (1) producing sheet samples and finalizing manufacturing know-how at our own prototyping lab, (2) starting sample work with customers, and (3) mass production at partner companies. Stages 1 and 2 are led by our in-house technical team; from stage 3, we provide technical support to production partners.
We will build the business foundation with ¥500 million in equity, and use a NEDO subsidy to accelerate application expansion and the transition to mass production.
Use of funds
* Program requirements may change with each call for applications. Based on NEDO's 10th call for proposals (July 2026 edition).
We will build a base for in-house manufacturing, evaluation, and customer supply, leading to initial sales and a transition to OEM mass production.
| Investment area | Specific use of funds | Outcomes |
|---|---|---|
| Manufacturing & evaluation base ¥300M (60%) | Prototyping and cell evaluation equipment Sheet coating equipment, cell fabrication and evaluation systems, dry room, etc. | Provide customers with samples and validation data from our own facilities. Iterate on specification tuning, prototyping, and cell evaluation in-house, and begin joint evaluation with customers |
| R&D and IP ¥100M (20%) | Application-specific R&D and IP creation Performance evaluation, establishing manufacturing conditions, filing related patents | Build the performance evidence and IP needed for adoption decisions. Accumulate application data, clarify technical advantages, and file related patents |
| Technical talent & operations ¥100M (20%) | Core hiring and operations Hiring technical, IP, and business development talent; working capital | Build a core team to lead the move to mass production. Codify manufacturing conditions and advance technology transfer to partners |
* Amounts and breakdowns are planned figures. Equipment specifications and scale will be finalized after obtaining quotes.
A proposed capital structure that balances staged fundraising with investor protection.
| Shareholder / category | Share class | Shares | Investment | Ownership |
|---|---|---|---|---|
| Founders & management | Common shares | 1,000,000 | — | 66.8% |
| External investors (J-KISS conversion) | Series A preferred | 200,000 | ¥250M | 13.4% |
| External investors (new Series A) | Series A preferred | 200,000 | ¥250M | 13.4% |
| Stock options (SO) | Stock acquisition rights | 96,000 | — | 6.4% |
| Total | — | 1,496,000 | ¥500M | 100.0% |
* Share counts and ownership are on a fully diluted basis. Issue price per share: ¥1,250 (pre-money valuation of ¥1.25B ÷ 1,000,000 existing shares).
* Post-money of ¥1.75B excludes the SO pool. Reference valuation including SOs: ¥1.87B.
Founders retain 66.8% on a fully diluted basis, ensuring fast decision-making for long-term R&D and commercialization.
A 6.4% SO pool is reserved in advance for future CxO candidates and top engineers.
Terms such as liquidation preference and anti-dilution will be negotiated with investors, balancing investor protection with growth investment through rights design.
By demonstrating IOP's performance, we will build the basis for higher corporate value, and also pursue next-stage grants such as the GI Fund.
* Timing and amounts are planned figures and will be updated once terms are finalized. * MS: milestone * GI Fund: Green Innovation Fund
We will build the business foundation with private investment and aim to meet the DTSU application requirements.
Assumptions: total ESS capacity 1 MWh / service life 30 years / standard cell life 15 years / IOP cell life 30 years
| Item | Standard LIB | LIB with IOP |
|---|---|---|
| Initial cost | ¥45.0M | ¥45.54M |
| Battery replacements (30 years) | 1 | 0 (no replacement needed) |
| Replacement cost after 15 years | ¥24.9M (battery + PCS) | ¥6.15M (PCS only) |
| 30-year TCO | ¥69.9M | ¥51.69M |
* With IOP separators, cell life is 30 years, so no battery replacement is needed (PCS replacement only).
* The added cost of IOP separators (¥540K) is included in the initial cost (internal estimate).
* IOP cell life is conservatively assumed at twice the standard (30 years).
For each application, we expect evaluation to take about 1–4 years, progressing from cell to pack to real-device evaluation.
| Application | Cell evaluation | Pack evaluation | Real-device evaluation |
|---|---|---|---|
| Drones First target | High-C continuous discharge | High-C cycling | Installation on actual aircraft |
| Power tools First target | High-current discharge | Drop and vibration | Fast-charge durability |
| Data centers | Short-term high-output characteristics, high-SOC life | Cabinet safety | Pilot evaluation |
| ESS (grid) | Initial characteristics, overcharge and short-circuit behavior | Propagation testing (fire spread), venting/detection/suppression design | Degradation under real operating SOC, review of anomaly detection logic |
| EVs (high-load) | Initial characteristics, basic safety | Fast-charge durability, high-temperature storage, low-temperature output, safety testing | Vehicle-equivalent durability, BMS control recalibration, high-SOC high-temperature storage degradation |
* Short evaluation periods are assumed for drones and power tools. Timelines are internal estimates and vary by customer, application, and standards. For agricultural machinery, evaluation steps and timelines will be set after confirming customer requirements.
* Each application moves to mass production after basic cell design and confirmation of mass-produced products. Timelines are internal estimates and vary by customer, application, and standards. For agricultural machinery, evaluation steps and timelines will be set after confirming customer requirements.
| Company Name | Separator Tech Japan Co., Ltd. |
|---|---|
| Japanese Name | セパレーターテックジャパン株式会社 |
| Address | 2F, Shiroichi Building 5-8-3 Shimbashi, Minato-ku, Tokyo 105-0004, Japan |
| Representative Director | Masayuki Taniguchi |
| Established | August 18, 2026 |
| Capital | JPY 10 million |
| Business Activities | Research, development, manufacturing, and sales of separators and related components for lithium-ion batteries Research, development, manufacturing, and sales of membrane materials such as separation membranes and functional sheets Research, development, and manufacturing of polymer, inorganic, and composite materials Contract testing, analysis, evaluation, inspection, and quality control services, and related consulting |
Since 1991, he has provided extensive hands-on consulting as an independent financial planner. As president of an investment trust management company, he established Japan's first real estate fund REIT. He currently serves as representative director of Mikuraya Shoji Co., Ltd. and other companies, running inbound brokerage for overseas investors and self-storage operations. In IT, he operates a range of portal sites, including E-trunk, Bike-ko, and Nihon Yosei College. He also has extensive international business experience in Hong Kong, Sri Lanka, Myanmar, and elsewhere. At Separator Tech Japan, he oversees finance, fundraising, and commercialization as Representative Director.
Left the doctoral program in Industrial Chemistry at the Graduate School of Engineering, Kyoto University; Ph.D. in Engineering (Kyoto University). After serving as Associate Professor at Kyoto University's Faculty of Engineering and at Tokyo Metropolitan University, he became Professor in the Department of Applied Chemistry, Graduate School of Engineering, Tokyo Metropolitan University, in April 2002. He developed the IOP separator. He has held positions including visiting university professor and NEDO review committee member. In April 2021, he was appointed Fellow of the National Institute for Materials Science (NIMS), and in October 2023, Integrated Team Leader of GteX (Green Technologies of Excellence).
We welcome inquiries about joint research, sample evaluation, business partnerships, and investment.
Contact Us / Request Materials