Sodium-Sulfur Battery Patents: Who Leads, Where the Gaps Are 2026
- Filing has gone flat, not up. the peak year was 2018 at four families and the 2022 midpoint sits at two — this is a mature, narrow field rather than a growth wave.
- One record dominates citations by a wide margin. a surgical-tool patent cited 776 times sits far ahead of the next most-cited molten-salt records, a sign the corpus pulls in adjacent thermal-management prior art.
- Filing concentrates in three offices. the United States, Japan and the EPO account for the bulk of the 174 published records, with Korea and Canada trailing well behind.
What this landscape covers
Sodium-sulfur and molten-salt battery technology occupies a narrow but persistent corner of patent activity built around beta alumina electrolyte, seal reliability and thermal management at operating temperatures well above ambient. The search set spans 174 published families filed between 2015 and the current data cut-off, concentrated almost entirely under the H01M battery classification with secondary activity in power-grid systems and motor control. This is a chemistry with a long institutional history — grid storage and utility backup — rather than a fast-moving consumer battery race.
Because publication lags filing by roughly eighteen months, the most recent filing years understate real activity; treat the tail of the trend as a floor, not a ceiling.
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Filing trend and technology composition
174 families published since 2015, classified predominantly under battery and cell chemistry codes, with secondary claim activity in grid power and motor-control systems that points to end-use context rather than core chemistry innovation.
A flat filing curve
Filings peaked at four families in 2018 and have not exceeded that since; the 2022 midpoint of two families confirms a plateau rather than a decline followed by recovery. This is consistent with a chemistry whose core claim space — beta alumina electrolyte, seal design, thermal enclosure — was substantially staked out by the late 2010s.
Concentrated in H01M, thin elsewhere
All 174 records sit under H01M (batteries, cells and fuel cells), with H02J (power supply and grid systems) and H05K (printed circuits and assemblies) as the next largest groups at 18 and 14 respectively. Vehicle thermal management (B60H) and glass/enamel compositions (C03C) appear only a handful of times, suggesting these adjacent applications remain lightly claimed relative to the core chemistry.
Shares are the percentage of the 174 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Sodium-Sulfur and High-Temperature Batteries with Eureka
This page is one run against one query. Ask Eureka your own question about sodium-sulfur and high-temperature batteries and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited and representative filings
US20150140378A1 — Molten salt battery and power supply system (Sumitomo Electric Industries, 2015-05-21)
The filing defines material choices — outer package, binder, anode active material, separator and electrolytic solution — across three operating-temperature bands spanning 25°C to 300°C, and adds a vibration-controlling portion aimed at severe-environment use where the battery is subject to shock.Abstract condensed from the original filing for length.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20160287265A1 | Autoclave Tolerant Battery Powered Motorized Surgical Hand Piece Tool and Motor Control Method | 776 |
| 2 | US5432026A | Cooling system for high temperature battery | 71 |
| 3 | JP2012134126A | Molten salt battery | 45 |
| 4 | GB2295264A | High temperature battery having cells in a thermally insulating case and immersed in a cooling liquid flowing… | 43 |
| 5 | JP2012182087A | Molten salt battery | 39 |
| 6 | US5578393A | Thermal contact sheet for high temperature batteries | 34 |
| 7 | GB2009473A | Borehole while drilling | 34 |
| 8 | US4332868A | High temperature battery cell comprising stress-free hollow fiber bundle | 30 |
| 9 | US3865630A | Electrochemical cell having heat pipe means for increasing ion mobility in the electrolyte | 28 |
| 10 | WO2012117916A1 | 溶融塩電池 | 26 |
Citation counts favour older filings simply because they have had longer to accumulate references; read them as a signal of influence within this searched set, not as a ranking of current technical importance.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Three patterns stand out once the filing trend, classification spread and citation table are read together.
A plateau, not a wave
With the 2022 midpoint at only two families and no year exceeding the 2018 peak, this chemistry shows the filing signature of an established, narrow field rather than one attracting fresh entrants.
Everything sits inside one subclass
Every record in this set classifies under H01M, with grid-power (H02J) and circuit-assembly (H05K) codes appearing as secondary context rather than independent innovation clusters.
One outlier record dominates influence
The most-cited document in the set is a surgical hand-piece patent, cited far ahead of the next records which are genuine molten-salt battery filings cited in the 40–70 range — a reminder that citation counts here reflect corpus composition, not just chemistry relevance.
Filing is mostly solo, with one strong pairing
Co-filing across this set is limited to ten pairs, the strongest being a university-industry pairing filed 24 times together, well ahead of any other combination.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to sodium-sulfur and high-temperature batteries, with the prior art for and against each one.
Who holds the ground
Recent-year momentum across the named assignees in this set is flat: every one of the organisations tracked shows zero filings in the latest year, consistent with the plateaued trend seen across the whole dataset. Positioning here is better read as accumulated portfolio depth than as a live filing race.
Sumitomo Electric Industries
The strongest co-assignee pairing in the dataset links this filer to a university partner across 24 joint records, the deepest single collaboration identified in the set, alongside its own representative filing on temperature-banded material selection.
NGK Insulators
A long-standing name in beta alumina ceramic electrolyte and molten-salt cell hardware, appearing among the set's named assignees with the same flat recent-year filing pattern as its peers.
UK Ministry of Defence
Appears among the tracked assignees, reflecting the field's dual history in defence-grade high-temperature power supply and civilian grid storage applications.
| Assignee | Recent year | YoY |
|---|---|---|
| Sumitomo Electric Industries, Ltd. | 0 | — |
| Kyoto University | 0 | — |
| Commander Corporation | 0 | — |
| NGK Insulators, Ltd. | 0 | — |
| UK Ministry of Defence | 0 | — |
| Ambri Research Ltd. | 0 | — |
| Dow Chemical Company | 0 | — |
| Ambri Inc. | 0 | — |
Where to take this analysis
The filing pattern here is settled enough that the open questions are about specific claims and gaps, not about a fast-moving trend.
Check freedom-to-operate on seal and enclosure claims
With H01M claim space this dense, seal reliability and thermal enclosure designs are the most likely place to run into prior art blocking a new filing.
Explore claims in EurekaProbe the under-claimed branches directly
Vehicle-thermal integration and glass-ceramic seal compositions show thin filing counts relative to the core electrolyte claims, which may leave room for a defensible first filing.
Run a white-space search in EurekaCommon questions about this landscape
Filing activity in this dataset has been flat since 2018, when the peak year recorded four families, and the 2022 midpoint fell to two. That pattern points to a mature, narrowly claimed field rather than one seeing fresh waves of filing. Because publication lags filing by around eighteen months, the very latest years will understate true activity, but the multi-year trend before that already shows a plateau rather than growth.
The dataset's strongest collaboration links Sumitomo Electric Industries with an academic partner across 24 joint filings, the deepest pairing identified. Other named assignees include NGK Insulators, with its long history in beta alumina ceramic electrolyte, and organisations tied to grid storage and defence applications such as the UK Ministry of Defence. All tracked assignees show zero filings in the most recent year, so current positioning reflects accumulated portfolios rather than active races.
Beta alumina is the solid ceramic electrolyte used in sodium-sulfur and related molten-salt cells to conduct sodium ions at high operating temperature. It sits at the core of the search terms behind this landscape alongside seal reliability and thermal management, and claims around its composition and manufacture are among the most densely filed in the H01M classification here. A new filing touching electrolyte composition should expect to navigate long-established prior art rather than open ground.
Relative to the dense core claims on electrolyte and seal design, this dataset shows thin coverage in vehicle-cabin thermal integration, glass-ceramic seal compositions, and grid-scale thermal cycling control. These branches sit adjacent to the core chemistry but are not saturated with filings, which makes them worth checking first for a defensible new claim. Thin coverage is not the same as guaranteed novelty, so any filing there still needs a proper freedom-to-operate check.
Not reliably on its own. The most-cited record in this dataset, at 776 citations, is a surgical hand-piece patent rather than a battery chemistry filing, while genuine molten-salt battery patents in the set are cited in the 40 to 70 range. Citation counts inside any searched corpus tend to favour older records simply because they have had more time to accumulate references, so they are better read as a signal of influence within this set than as a guide to which technology is currently most important.
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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.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.