Metal-Air & Li-S Battery Patents: Top Companies & Filing Trends 2026
- 24.3% concentration at the top. The five leading assignees account for 272 of the 1,120 records in scope — a narrow group holding a quarter of the field.
- Filing has cooled from its 2019 peak. Annual filings ran from 90 at their 2019 peak down through 52 in 2021 to 30 in 2024, a 42% pull-back over that span.
- H01M carries two-thirds of the corpus. 752 of 1,120 records touch the core battery-cell subclass, while separation, electrolytic and EV-propulsion classes each sit in the single digits of share.
Filing growth compares 2021 (52 records) with 2024 (30) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 1,120 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This landscape tracks 1,120 published records filed between 2015 and the 2026 cut-off that combine metal-air battery terminology with claims touching material phase, surface layer chemistry, particle morphology, mechanical strength, state of charge or electrode capacity. The search string deliberately pairs a battery-architecture term with a materials-and-performance term, so the corpus is weighted toward records where the inventive step sits in the physical or electrochemical detail rather than in system integration alone.
Because publication lags filing by roughly 18 months, the most recent one to two years in any trend understate real filing activity; 2024 is the last year that can be read as a complete picture. Family counts, rather than raw document counts, are used throughout for cross-jurisdiction comparisons so that continuation filings and multi-country duplicates do not inflate any one assignee's apparent share.
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Filing trend and technology composition
Two views of the same 1,120-record corpus: how filing volume has moved year over year, and which IPC subclasses carry the claim density. Because a single record can carry several IPC classes, the composition shares add up to more than 100% of the record total.
Filings rose to a 2019 peak, then pulled back
Annual filings climbed to 90 in 2019, the high point of the series, before easing to 52 by 2021 and 30 by 2024 — a 42% decline over that three-year window. 2025 and 2026 figures are still filling in under the publication lag and should not be read as a continued fall.
H01M dominates; the rest is materials and systems periphery
H01M (batteries, cells & fuel cells) covers 67.1% of the 1,120 records, by far the largest single class. The next tier — B01J, C01B, H02J, C25B, B01D, H01L and B60L — each sits between roughly 4% and 8%, reflecting catalysis, inorganic compound chemistry, grid integration, electrolytic production, separation media, semiconductor content and EV propulsion as adjacent but secondary claim territory.
Shares are the percentage of the 1,120 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Metal-Air & Lithium-Sulfur Batteries Patent Landscape with Eureka
This page is one run against one query. Ask Eureka your own question about metal-air & lithium-sulfur batteries patent landscape and every answer comes back with the patent numbers behind it.
Try EurekaA representative filing and the most-cited anchors
Rechargeable and refuelable metal air electrochemical cell (US20050123815A1)
Filed by Evionyx, this 2005 record describes a metal-air electrochemical cell built around a removable, rechargeable metal fuel anode paired with an air cathode and a third electrode, with a separator in ionic communication with the anode's major surface. A second embodiment splits the design into a discharging cell — where the air cathode structure receives the removable fuel anode and produces electrical energy as the metal fuel oxidises — and a separate recharging cell.The split discharge/recharge architecture is the structural idea most downstream filers have had to design around or license.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5898282A | Control system for a hybrid vehicle | 408 |
| 2 | US7098405B2 | High performance support-separator for communications cables | 274 |
| 3 | US20130224632A1 | Novel separators for electrochemical systems | 230 |
| 4 | US6639152B2 | High performance support-separator for communications cable | 207 |
| 5 | US6127061A | Catalytic air cathode for air-metal batteries | 198 |
| 6 | US20150171398A1 | Electrochemical separators with inserted conductive layers | 182 |
| 7 | US20130189592A1 | Part solid, part fluid and flow electrochemical cells including metal-air and li-air battery systems | 164 |
| 8 | US20050199415A1 | Flame retardant and smoke suppressant composite high performance support-separators and conduit tubes | 162 |
| 9 | US20100112454A1 | Compliant seal structures for protected active metal anodes | 158 |
| 10 | US5939354A | Perovskite-type metal oxide compounds and method for preparing the compounds | 155 |
Citation counts favour older filings that have had more time to accumulate references — read them as a signal of influence within this searched corpus, not as a ranking of current technical importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three readings of the same corpus, each pointing at a different decision: where the field is crowded, where volume is thinning, and where citation weight actually sits.
A narrow leadership group, not a single dominant filer
The five most active assignees hold 272 of the 1,120 records in scope — a meaningful share, but no single entity approaches a majority. The leader sits at 96 records against a fifth-place figure of 34, so the gap between first and fifth is itself a signal that no one assignee has locked the core architecture down.
Volume has thinned since the 2019 peak
Filings fell from 52 in 2021 to 30 in 2024, a 42% contraction over three years, after peaking at 90 in 2019. Several of the more active named assignees show flat or negative year-on-year movement into the latest year, though that year is still incomplete under the publication lag.
The oldest anchors still carry the most citation weight
The most-cited record in the corpus, a hybrid-vehicle control system, sits well ahead of the next tier, and several of the highest-cited documents predate the 2015 filing window that defines this corpus's scope. That skew is typical of citation counts inside any searched corpus — older filings have simply had more years to accumulate references.
One core class, several adjacent single-digit classes
H01M's 67.1% share dwarfs every other subclass; the next largest, B01J, sits at 7.6%. That gap suggests most inventive activity is being claimed as core battery-cell subject matter, with materials, separation and systems-integration classes treated as secondary or dependent claim territory rather than as separately pursued fronts.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to metal-air & lithium-sulfur batteries patent landscape, with the prior art for and against each one.
The assignee landscape
The ranking covers 100 companies counted by family, from a leader at 96 records down through a long tail of single- and few-filing entrants. It is the complete ranking the dataset returns, not a top-50 or top-100 cut.
A clear leader without a runaway lead
The top-ranked assignee holds 96 of the 1,120 records, well ahead of fifth place at 34, but still a fraction of the total corpus. That gap between first and the rest of the top five is wide enough to matter for freedom-to-operate work, without being wide enough to call the field settled.
A third of the field sits with ten assignees
The ten most active assignees combine for 409 of the 1,120 records, just over a third of everything in scope. The remaining two-thirds is spread across the rest of the ranked 100 and beyond, which is where most freedom-to-operate risk for a new entrant will actually be checked.
Co-filing is limited and concentrated
Only ten co-assignee pairs appear in the corpus, and the strongest of them link a single company to individual named inventors rather than to other corporate assignees. That pattern points to filing being done largely independently, with joint development agreements the exception rather than the norm in this dataset.
| Assignee | Recent year | YoY |
|---|---|---|
| Form Energy, Inc. | 2 | -50% |
| University of Delaware | 0 | — |
| Phinergy Ltd. | 0 | — |
| EnPower, Inc. | 0 | — |
| California Institute of Technology | 0 | -100% |
| InSound Medical, Inc. | 0 | — |
| Ionic Materials, Inc. | 0 | — |
| Cable Components Group, LLC | 0 | — |
Where to take this next
The dataset points to specific follow-up work rather than a single conclusion — concentration at the top, a cooling filing trend, and a narrow core class each suggest a different next question.
Check freedom-to-operate against the top 10
With 36.5% of all records held by ten assignees, a new filing in this space should be checked against that group's claim scope before anything else, particularly around the core H01M subject matter.
Run an FTO scan in EurekaMap the under-claimed branches
The gap between H01M's 67.1% share and the single-digit shares of adjacent classes suggests specific claim territory — separator design, catalyst durability, anode exchange mechanisms — that is not yet heavily contested.
Explore white space in EurekaTrack momentum, not just totals
Several of the most active named assignees show flat or declining recent-year filing counts. Whether that reflects a maturing core design or a shift to trade-secret protection is worth checking assignee by assignee.
Monitor assignee activity in EurekaCommon questions on this landscape
The dataset ranks 100 assignees by family count, with the leader holding 96 records and the field's top five combining for 272 records, or 24.3% of the 1,120 records in scope. That leaves roughly three-quarters of the corpus spread across a long tail of companies and research institutions, so no single filer controls the technology outright. A freedom-to-operate check should look at the top ten as a group, since they together hold 36.5% of all records, rather than focusing on the single leader.
Filing activity peaked in 2019 at 90 records and has since declined to 30 records in 2024, a 42% drop over the 2021-to-2024 window. That is the last three-year period that can be read reliably, because publication lags filing by around 18 months and the 2025-2026 figures are still incomplete. The honest read is a pull-back from a 2019 high rather than a technology in early growth, though the incomplete recent years mean the true current pace is somewhat higher than the raw numbers show.
H01M, the core batteries-and-fuel-cells subclass, covers 67.1% of the 1,120 records in scope, making it by far the dominant classification. Secondary classes include B01J (chemical and catalytic processes) at 7.6%, C01B (inorganic compounds) at 7.5%, H02J (power supply and grid systems) at 6.5%, and C25B, B01D, H01L and B60L each in the mid-single digits. Because records often carry more than one class, these figures do not sum to 100% and should be read as separate coverage measures, not as parts of a whole.
This 2005 Evionyx filing describes a metal-air electrochemical cell with a removable, rechargeable metal fuel anode, an air cathode, a third electrode and a separator in ionic communication with the anode surface, along with a split discharging-cell/recharging-cell architecture. It is one of the more frequently referenced structural approaches to refuelable metal-air design in this corpus. Anyone designing a refuelable anode-exchange system should review its specific claim language closely, since the split-cell architecture is the structural idea most later filings have had to design around.
The gap between H01M's 67.1% share and the much smaller shares held by separation, electrolytic-production and semiconductor-adjacent classes suggests those peripheral areas are less densely claimed relative to core battery-cell subject matter. Specific candidates include separator ionic-communication design, air-cathode catalyst durability, refuelable anode exchange mechanisms, and state-of-charge sensing tailored to metal-fuel cells. High density in H01M means that core claim space is occupied, not that it is exhausted, so any new filing there still needs a careful prior-art check rather than being avoided outright.
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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.