Sodium-Sulfur Battery Patent Landscape 2026
Sodium-Sulfur Battery Patent Landscape in 2026
The sodium-sulfur battery patent space is highly concentrated, with NGK Insulators holding an outsized lead among 957 patent families in scope, and Japan anchoring the dominant filing jurisdiction. Activity peaked in 2019 and has since eased, placing the field in a decline stage where adjacent branches such as grid integration and advanced ceramics remain comparatively sparse.
NGK Insulators leads a heavily concentrated field
NGK Insulators Ltd ranks first with 761 patent records, far ahead of second-ranked Hitachi Ltd at 268 and third-ranked Tokyo Electric Power Co Holdings Inc at 221. The top five filers together account for 49% of the combined output of the hundred largest filers, signalling an unusually tight competitive structure.
The tier gap between NGK Insulators and the rest of the field is substantial: its patent record count is nearly three times that of Hitachi, the nearest challenger. The second and third tiers—GS Yuasa Corp (142), Honeycomb Battery Co (127), and the Research Institute of Industrial Science & Technology (94)—are closely bunched, with no single challenger approaching NGK’s scale.
| # | Applicant | Patent records | Share |
|---|---|---|---|
| 1 | NGK Insulators Ltd | 761 | |
| 2 | Hitachi Ltd | 268 | |
| 3 | Tokyo Electric Power Co Holdings Inc | 221 | |
| 4 | GS Yuasa Corp | 142 | |
| 5 | Honeycomb Battery Co | 127 | |
| 6 | RES INST OF IND SCI & TECH | 94 | |
| 7 | General Electric Co | 84 | |
| 8 | Ford Motor Co | 49 | |
| 9 | Sumitomo Electric Industries Ltd | 39 | |
| 10 | POSCO Holdings Inc | 36 |
| # | Applicant | Patent records | Share |
|---|---|---|---|
| 11 | Mitsubishi Heavy Industries Ltd | 34 | |
| 12 | Hughes Aircraft Co | 34 | |
| 13 | Vissers Battery Corp | 32 | |
| 14 | Field Upgrading USA Inc | 32 | |
| 15 | SK Innovation Co Ltd | 31 | |
| 16 | EAST CHINA ELECTRIC POWER TEST & RES INST | 30 | |
| 17 | Chloride Silent Power Ltd | 28 | |
| 18 | Shanghai Electric Enterprise Development Co Ltd | 28 | |
| 19 | Kyoto University | 28 | |
| 20 | Semicon Energy Lab Co Ltd | 25 |
NGK’s dominant position reflects decades of industrial NaS battery commercialisation centred on utility-scale stationary storage. Challengers, particularly South Korean and Chinese entrants, are building positions but remain well behind in cumulative depth. New entrants targeting niche applications—such as electric vehicles or aerospace—face a dense prior-art thicket in core cell chemistry.
Filings from the most recent 18–24 months are subject to publication lag and are likely under-counted; the apparent decline in 2024–2026 data should be interpreted cautiously. Longer-window growth, applicant concentration, and technology-route coverage are therefore more reliable signals than the latest-year bar alone.
Filing activity peaked in 2019; cell chemistry dominates the technology mix
Two charts together reveal both the temporal trajectory and the technological breadth of sodium-sulfur battery patenting: annual filing volume shows a clear peak-and-ease pattern, while the IPC branch breakdown shows heavy concentration in battery cell technology with a long tail of adjacent disciplines.
Annual filing trend
Annual filings climbed to a peak of 194 records in 2019, then stepped down through 2022–2023 (86–94 records), with 2024 and 2025 figures (56 and 50 respectively) reflecting both genuine softening and publication lag. The lifecycle evidence confirms the field has eased from its 2019 peak; the most recent two years remain under-counted and should not be read as the final level of activity.
↗ Hover for values · click a bar to ask EurekaTechnology composition
H01M (Batteries, cells & fuel cells) dominates overwhelmingly with 3,571 patent records, confirming that fundamental cell design and chemistry is where the bulk of competitive effort is directed. The next largest branches—H02J (Power supply & grid systems, 342 records) and C04B (Ceramics, cement & refractories, 230 records)—are each an order of magnitude smaller, pointing to comparative sparsity in grid integration and solid electrolyte materials relative to the core cell branch.
↗ Hover for values · click a bar to ask EurekaHighly cited patent families surfaced by the query
Citation-heavy patent families returned by the query. Use this section as citation context, not as a curated list of the most topic-specific patents.
Molten sodium battery and partition wall for molte…
A molten sodium battery includes molten sodium making an anode active material, a cathode active material, a sodium container accommodating the molten sodium therein, a partition wall including an anode chamber in an interior thereof, and a cathode container air-tightly accommodating the cathode active material and the partition wall therein. The molten… (excerpt from the patent abstract)
| # | Patent | Citations |
|---|---|---|
| 1 | Coated electroactive materials | 315 |
| 2 | Lithium ion conductive solid electrolyte and produ… | 237 |
| 3 | Electrochemical cells with carbon nanofibers and e… | 230 |
| 4 | Alkali Metal Secondary Battery Containing a Carbon… | 161 |
| 5 | Battery thermal management system and method | 149 |
| 6 | Trade-in battery system | 149 |
| 7 | Chemical-Free Production of Graphene-Encapsulated … | 148 |
| 8 | Redox flow battery | 143 |
Ranked by total forward citations. Citation counts favour older and broadly cited patent families, and broad or adjacent patents may appear when they match the search scope. Treat this section as citation context, not as a curated list of the most topic-specific patents. Some patent titles may be shown in their original, non-English language where an accurate translation could not be guaranteed.
What the structure means for R&D investment
Japan-centred jurisdiction profile shapes the risk-return calculus for new entrants and incumbents alike.
Decline stage: post-peak, core cell chemistry is crowded
The lifecycle evidence labels this field as Decline, with annual filings easing back from the 2019 peak. Core H01M cell chemistry is densely patented, leaving little unclaimed ground for incremental cell innovations. R&D investment is better directed at adjacent enabling technologies or next-generation architectures that sit outside the crowded core.
Lifecycle: DeclineNGK Insulators holds a structurally dominant position
The top five filers account for 49% of the hundred largest filers’ combined output, and NGK Insulators alone commands 761 patent records—nearly three times Hitachi’s count. This level of concentration means any new entrant risks immediate freedom-to-operate friction. Differentiation through materials chemistry (ceramics, electrolyte engineering) or application-specific design (vehicle traction, aerospace) offers more viable paths than competing head-on in utility-scale cell architecture.
High concentrationNGK–TEPCO and GS Yuasa–Yuasa Battery are the anchor partnerships
The most active co-filing pair is NGK Insulators (Nippon Gaishi) with Tokyo Electric Power Co Holdings, sharing 125 co-filed records—a utility-manufacturer dyad reflecting Japan’s grid-storage deployment model. GS Yuasa Corp and Yuasa Battery Co Ltd form the second largest partnership (85 records), while Hitachi Ltd and Tokyo Electric Power Co Holdings account for 56 records. The Research Institute of Industrial Science & Technology (POSCO group) and POSCO Holdings Inc collaborate on 36 records, representing the leading Korean axis. These relationships consolidate IP around established deployment channels and may limit licensing options for independent innovators.
Ecosystem partnershipsJapan dominates; US and Europe are secondary; China is an emerging jurisdiction
Japan leads with 1,187 patent records filed, reflecting the country’s role as the primary commercialisation base for industrial NaS batteries. The United States (896 records) and Europe via EPO (456 records) represent significant secondary markets. China (283 records) is growing in relevance, with Shanghai Electric Sodium Sulfur Energy Storage Technology and State Grid Shanghai both appearing in the collaboration network—a signal of increasing Chinese deployment interest. South Korea (146 records) rounds out the primary jurisdictions.
Japan-centredGo beyond the landscape: Eureka’s TRIZ Solution agent breaks down an R&D problem and returns patented concept solutions, each with a technical approach and cited patent & literature evidence.
| Applicant | Collaborator | Co-filings |
|---|---|---|
| NGK Insulators Ltd | Tokyo Electric Power Co Holdings Inc | 125 |
| GS Yuasa Corp | Yuasa Battery Co Ltd | 85 |
| Hitachi Ltd | Tokyo Electric Power Co Holdings Inc | 56 |
| Research Institute of Industrial Science & Technology (RIST) | POSCO Holdings Inc | 36 |
| Shanghai Electric Sodium Sulfur Energy Storage Technology Co Ltd | State Grid Shanghai Municipal Electric Power Co | 9 |
| Hitachi Ltd | Hitachi Engineering Co Ltd | 8 |
| Shanghai Electric Sodium Sulfur Energy Storage Technology Co Ltd | Shanghai Automation Instrumentation Co Ltd | 4 |
| Tokyo Electric Power Co Holdings Inc | Tokyo Metropolitan University | 3 |
| GS Yuasa Corp | Kawasaki Heavy Industries Ltd | 3 |
| Yuasa Battery Co Ltd | Kawasaki Heavy Industries Ltd | 3 |
Co-filing pairs, ranked by the number of jointly-filed patent families.
NGK Insulators leads; Hitachi and TEPCO form the main challenger tier
The applicant landscape is a classic leader-plus-pack structure: one dominant incumbent with broad coverage across cell chemistry, and a set of challengers focused on specific sub-themes such as battery management systems and grid integration.
NGK Insulators Ltd
NGK Insulators holds 761 patent records, concentrating almost entirely on H01M 10 (core battery cell chemistry, 764 records), with secondary positions in H01M 2 (cell components, 175 records) and H01M 50 (battery accessories, 118 records). Recent momentum shows a 24% decline in recent filings versus the prior period, consistent with the field’s post-peak lifecycle. Its portfolio breadth and depth create a high prior-art barrier across all fundamental NaS cell design dimensions.
families: 761Hitachi Ltd
Hitachi Ltd ranks second with 268 patent records, also concentrated in H01M 10 (268 records), with smaller positions in H01M 2 (34 records) and H01M 4 (electrode materials, 17 records). Hitachi’s collaboration with Tokyo Electric Power Co Holdings (56 co-filed records) and with Hitachi Engineering Co Ltd (8 records) points to a system-integration and grid-management emphasis rather than pure cell chemistry. No recent momentum figure is available in evidence for Hitachi beyond its ranking position.
families: 268| Applicant | Recent (3 yrs) | Trend |
|---|---|---|
| NGK Insulators Ltd | 13 | ▼ -24% |
Under-served branches adjacent to the dominant cell-chemistry core
Beyond the dominant H01M battery cell branch, several IPC classes show meaningful but comparatively sparse activity. These represent under-served adjacent areas where differentiated technical work may face less prior-art density, though they are not validated commercial opportunities without further freedom-to-operate analysis.
H02J · Power supply & grid systems
With 342 patent records, H02J is the largest adjacent branch but still represents only 6% of the leading H01M count. Given that NaS batteries are primarily deployed for grid-scale stationary storage, the relatively low coverage of power-system integration, inverter control, and grid-ancillary-service architectures is notable. Engineers working on smart-charging protocols, grid-side battery management, or renewable-coupling control systems may find comparatively less prior-art density here than in core cell design. Entry requires cross-disciplinary capability spanning power electronics and electrochemistry.
Search this in Eureka →C04B · Ceramics, cement & refractories
C04B covers the beta-alumina solid electrolyte ceramics that are central to NaS battery function, yet it accounts for only 230 patent records—roughly 4% of the H01M total. Given that solid electrolyte performance and manufacturing yield are key cost and reliability bottlenecks for NaS batteries, this relative sparsity suggests that ceramic processing routes, sintering techniques, and defect engineering may be under-patented relative to their technical importance. Researchers with ceramic processing expertise could find viable differentiation here, particularly in novel deposition or co-firing processes not yet captured in the existing literature.
Search this in Eureka →How leading applicants differ by technology route
Strength of each leader across the main technology routes.
| Player | H01M 10 · Batteries, cells & fuel cells | H01M 4 · Batteries, cells & fuel cells | H01M 2 · Batteries, cells & fuel cells | H01M 50 · Batteries, cells & fuel cells | H02J 7 · Power supply & grid systems |
|---|---|---|---|---|---|
| NGK Insulators Ltd | Strong · 764 | Emerging · 48 | Moderate · 175 | Emerging · 118 | Emerging · 104 |
| Hitachi Ltd | Strong · 268 | Absent | Emerging · 34 | Absent | Emerging · 8 |
| Tokyo Electric Power Co Holdings Inc | Strong · 192 | Emerging · 24 | Emerging · 26 | Emerging · 11 | Emerging · 13 |
| Nanotek Instruments Inc | Strong · 101 | Strong · 96 | Absent | Absent | Absent |
| GS Yuasa Corp | Strong · 148 | Absent | Emerging · 21 | Emerging · 12 | Absent |
| General Electric Co | Strong · 95 | Absent | Moderate · 37 | Moderate · 28 | Emerging · 10 |
| Research Institute of Industrial Science & Technology (RIST) | Strong · 84 | Moderate · 23 | Strong · 50 | Absent | Absent |
Frequently asked questions
The corpus in scope contains 957 patent families. Japan leads in filing volume with 1,187 patent records, followed by the United States with 896 and Europe via EPO with 456.
NGK Insulators Ltd is the dominant holder with 761 patent records, approximately three times the count of second-ranked Hitachi Ltd (268 records). The top five filers together account for 49% of the combined output of the hundred largest filers.
The field is assessed as being in a Decline stage. Annual filings peaked at 194 records in 2019 and have eased since, though the most recent 18–24 months of data are subject to publication lag and likely under-count actual activity.
H01M (Batteries, cells & fuel cells) dominates with 3,571 patent records. The next largest branches are H02J (Power supply & grid systems, 342 records) and C04B (Ceramics, cement & refractories, 230 records), both significantly smaller than the core battery branch.
The leading co-filing pair is NGK Insulators and Tokyo Electric Power Co Holdings (125 co-filed records), reflecting Japan’s grid-storage deployment ecosystem. GS Yuasa Corp and Yuasa Battery Co Ltd follow with 85 co-filed records, and Hitachi Ltd and Tokyo Electric Power Co Holdings account for 56.
H02J (Power supply & grid systems) and C04B (Ceramics, cement & refractories) are the largest adjacent branches by record count but remain sparse relative to the dominant H01M core. C01B (Non-metallic elements & inorganic compounds) and G01R (Electric & magnetic measurement) also show comparatively low coverage given their technical relevance to NaS battery development.
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Disclaimer. This page is generated from PatSnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
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