Molten Salt Electrolysis Patents: Who Leads, Filing Trends 2026
- Filing rebounded sharply after 2021, up 129% from 14 filings in 2021 to 32 in 2024 — the last year the data can be treated as complete.
- The top 5 assignees hold just 25.8% of the 1,003 records in scope, and the top 10 only 35.4% — concentration here is real but far from a duopoly.
- C25C electrolytic metal production anchors two-thirds of records (67.1%), while separation processes (B01D, 4.8%) and alloy claims (C22C, 8.0%) remain comparatively open.
Filing growth compares 2021 (14 records) with 2024 (32) — 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 1,003 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Molten salt electrolysis is the industrial route for reducing rare earth and light-metal oxides to metal using a fused electrolyte, an anode/cathode pair and a lined electrolytic cell. The search underpinning this page combines electrolysis and reduction terminology with the operational vocabulary that separates a working process from a laboratory curiosity — current efficiency, anode effect, cell lining, fluorine emission, alloy tapping and oxide feeding. That combination pulls in both aluminium-style Hall-Héroult variants and rare earth-specific reduction cells, which is why the IPC composition spans electrolytic production classes alongside alloys and refractories.
1,003 records sit in scope between 2015 and the 2026-07-31 cut-off. Because publication trails filing by roughly 18 months, the most recent filing years are undercounts rather than a genuine slowdown; 2024 is the last year the trend can be read as complete.
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Filing trend and technology composition
Two views of the same 1,003 records: how filing activity has moved year over year, and which IPC subclasses carry the claim density.
Filing rebounded after a mid-decade dip
Filings peaked at 46 in 2018, cooled, then climbed again — 14 in 2021 to 32 in 2024, a 129% rise over that span. Treat 2025 and 2026 figures as partial; they will fill in as publications catch up with filing dates.
Claim density concentrates in electrolytic production
C25C (electrolytic metal production) touches 67.1% of the 1,003 records, far ahead of C25B (electrolytic production of compounds, 24.7%) and C22B (metal extraction and refining, 14.1%). Refractories (C04B, 8.8%), alloys (C22C, 8.0%) and separation processes (B01D, 4.8%) sit well below that line — smaller claim footprints, not necessarily less relevant technology.
Shares are the percentage of the 1,003 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Molten Salt Electrolysis of Rare Earth Metals with Eureka
This page is one run against one query. Ask Eureka your own question about molten salt electrolysis of rare earth metals and every answer comes back with the patent numbers behind it.
Try EurekaKey patents shaping the field
US20240141529A1 — Method for producing metal aluminum by molten salt electrolysis of aluminum oxide
The method uses an electrolytic cell split into anode and cathode chambers filled with anolyte, catholyte and an alloy medium melt. Aluminium oxide feedstock is added to the anode chamber and powered electrolysis yields high-purity metal aluminium at the cathode chamber, with the disclosure emphasising strong operational adaptability and broad material selectivity.Filed by Central South University, published 2024-05-02.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US6048507A | Process for the purification of lithium carbonate | 172 |
| 2 | EP0116809A1 | Cermets and their manufacture | 151 |
| 3 | US4999097A | Apparatus and method for the electrolytic production of metals | 130 |
| 4 | US20110200508A1 | Processes for preparing highly pure lithium carbonate and other highly pure lithium containing compounds | 128 |
| 5 | US4374761A | Inert electrode formulations | 115 |
| 6 | US20010028871A1 | Process for the purification of lithium carbonate | 104 |
| 7 | US4670110A | Process for the electrolytic deposition of aluminum using a composite anode | 93 |
| 8 | US4585618A | Cermets and their manufacture | 87 |
| 9 | US4374050A | Inert electrode compositions | 86 |
| 10 | US4399008A | Composition for inert electrodes | 82 |
Citation counts reward age inside a searched corpus — read them as a signal of influence on later filings, not as a measure of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for a filing decision
Three findings that change where a new filing should sit, and who to watch while it moves through prosecution.
No single assignee controls the field
The leader holds 119 records against a field of 1,003, and the gap from fifth place (24) to tenth (17) is shallow. That pattern — a modest lead plus a long tail of single- and few-filing entrants — means freedom-to-operate analysis has to check many small portfolios, not just the obvious names.
Activity is rebuilding, not cooling off
After a mid-decade dip, filings rose from 14 in 2021 to 32 in 2024. Because publication lags filing by around 18 months, the 2025–2026 figures in the raw trend understate what is actually happening now — do not read them as a retreat.
Separation and refractory claims are thinner
Electrolytic metal production (C25C) carries claim density more than an order of magnitude above separation processes (B01D). Refractories (C04B, 8.8%) and alloys (C22C, 8.0%) sit in between — narrower but not empty, and worth a design-around search before assuming they're clear.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to molten salt electrolysis of rare earth metals, with the prior art for and against each one.
Assignee landscape and where new entrants can still move
The ranked list covers 100 companies across the full 1,003-record set. Reading it alongside the recent-year momentum data shows a field where early movers hold volume but have gone quiet, leaving room for active filers to build position.
Volume leadership sits with legacy electrolysis specialists
The top-ranked assignee's 119 records reflect decades of cell-design and reduction-process filing rather than a recent surge — recent-year momentum data shows several of the largest historical filers, including the leader, at zero filings in the latest year.
The drop-off past the leader is gradual
Fifth place holds 24 records and tenth holds 17 — a shallow slope compared with the leader's 119. That gap is where a well-timed filing program can climb the ranking without displacing the top position.
Collaboration is limited and clustered
Only five co-assignee pairs appear across the dataset, and the strongest recur around the same handful of organisations. Joint filing is not yet a common route into this field, which favours solo filers willing to build their own prior-art base.
| Assignee | Recent year | YoY |
|---|---|---|
| Moltech Invent S.A. | 0 | — |
| Nemaska Lithium | 0 | — |
| Aluminum Company of America (Alcoa) | 0 | — |
| Inner Mongolia United Industry Co., Ltd. | 0 | — |
| Toho Titanium Co., Ltd. | 0 | — |
| Osaka Titanium Technologies Co., Ltd. | 0 | — |
| Umicore (Belgium) | 0 | -100% |
| Sumitomo Light Metal Industries, Ltd. | 0 | — |
Where to take this analysis
The landscape points to specific next questions rather than a single answer — each depends on what a team is trying to protect or clear.
Check freedom-to-operate against the long tail
With the top 10 holding only 35.4% of the 1,003 records, a clearance search has to look well past the obvious leaders into the ranked field of 100 companies.
Explore the assignee rankingScope a claim around under-claimed sub-areas
Separation processes and alloy-medium cathode design carry noticeably lower claim density than core electrolytic production classes — worth a targeted prior-art pull before drafting.
Run a white-space search in EurekaTrack momentum, not just historical volume
Several of the largest historical filers show zero filings in the latest year. Current activity may be concentrated among different, more active assignees than the raw leaderboard suggests.
Monitor filer activity in EurekaCommon questions about this landscape
The leading assignee in this dataset holds 119 of the 1,003 records in scope, well ahead of the rest of the field. But concentration falls off quickly after that: the top 5 assignees together hold only 25.8% of all records, and the top 10 hold 35.4%. That means no single company controls freedom-to-operate here, and a clearance search needs to cover a long tail of smaller filers, not just the named leader.
Filing grew substantially in the recent period that can be read reliably: from 14 filings in 2021 to 32 in 2024, a 129% increase. The raw trend shows lower numbers in 2025 and 2026, but that is an artefact of publication lag — patent applications typically publish around 18 months after filing, so the most recent one to two years always look understated. Based on the complete data through 2024, activity is rebuilding rather than cooling.
C25C, electrolytic metal production, appears in 67.1% of the 1,003 records in scope, making it by far the densest class. C25B (electrolytic production of compounds) follows at 24.7%, and C22B (metal extraction and refining) at 14.1%. Because a single record can carry multiple IPC classes, these shares add up to more than 100% — they describe overlapping claim footprints, not a strict partition of the field.
The IPC composition shows separation processes (B01D, 4.8% of records) and alloy claims (C22C, 8.0%) sitting far below the dominant electrolytic-production classes. Practically, that points to fewer filed claims around separating tapped alloy from residual electrolyte, alloy-medium cathode chamber design, and refractory cell-lining chemistry (C04B, 8.8%) relative to the core reduction-cell art. These are narrower branches, not empty ones, so a design-around search is still worthwhile before drafting.
US20240141529A1, filed by Central South University and published 2024-05-02, describes a method for producing metal aluminium by molten salt electrolysis of aluminium oxide using a cell divided into anode and cathode chambers with anolyte, catholyte and an alloy medium melt. It is a representative recent filing rather than the oldest or most-cited record in this dataset, and it illustrates the alloy-medium chamber approach that sits adjacent to the higher-density core electrolytic-production claims. Anyone filing near cathode-chamber alloy media or aluminium oxide feed configurations should read it closely against their own claim scope.
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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.