Critical Metal Electrowinning Patents: Leaders & Filing Trends 2026
Filing growth compares 2021 (18 records) with 2024 (7) — 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 986 records in scope (CR5), not by the ranked leaders only.
What the electrowinning patent record actually shows
Critical metal electrowinning sits at the intersection of hydrometallurgy and electrochemistry: pulling cobalt, nickel, manganese, rare earths or scandium out of leach solutions using an electric current rather than smelting or solvent extraction alone. The dataset behind this page spans 986 published records filed between 2015 and 2026, drawn from a search built around the core electrowinning terms for each of these metals. It is a smaller, more concentrated field than general battery-materials or mining patenting: a handful of assignees built early anode and electrolyte chemistry positions and have held them since.
The most-cited records in the corpus date back to the 1990s and early 2000s, which is normal for a citation-based ranking inside a searched field — older documents accumulate citations simply by being available longer. Read them as markers of foundational chemistry, not as evidence that the technology has stopped moving.
Filing trend and technology composition
Two views of the same 986 records: how filing activity has moved year on year, and which IPC subclasses the claims actually sit in. Because a single record can carry several IPC codes, the class shares below add up to more than 100% of the record total.
Filing trend, 2017-2026
Filings ran from 7 in 2017 to a peak of 29 in 2019, then declined to 7 by 2024 — a 61% drop over the 2021-2024 window. 2025 and 2026 show fewer records, but that reflects publication lag of roughly 18 months rather than a genuine collapse in filing activity.
Technology composition by IPC subclass
C25C (electrolytic metal production) and C22B (metal extraction & refining) each appear in close to half of all 986 records, confirming these as the two load-bearing classes. C25B, C01G and C25D each sit in the 10-14% range, marking secondary but recurring claim territory around compound electrolysis, metal compounds and electroplating. B01D, C01B and H01M each cover under 10% of records, the smallest and least contested slices of the corpus.
Shares are the percentage of the 986 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Critical-Mineral Refining & Separation: Critical Metal Electrowinning Patent Landscape with Eureka
This page is one run against one query. Ask Eureka your own question about critical-mineral refining & separation: critical metal electrowinning patent landscape and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited prior art and a representative filing
US8357271B2 — Anode for use in zinc and cobalt electrowinning and electrowinning method
Assigned to Doshisha, this filing targets a specific failure mode in electrowinning anodes: manganese compound deposition during zinc electrowinning and cobalt oxyhydroxide deposition during cobalt electrowinning. The claimed anode uses an amorphous iridium oxide catalytic layer on a conductive substrate, with a cobalt-electrowinning variant using amorphous iridium oxide or ruthenium-based coatings.Published 2013-01-22 — illustrates how narrowly the strongest claims in this field are drawn around anode surface chemistry rather than the broader electrowinning process.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4528084A | Electrode with electrocatalytic surface | 101 |
| 2 | US5650057A | Chloride assisted hydrometallurgical extraction of metal | 78 |
| 3 | US6171564B1 | Process for extraction of metal from an ore or concentrate containing nickel and/or cobalt | 67 |
| 4 | US5645708A | Chloride assisted hydrometallurgical copper extraction | 61 |
| 5 | US20010001650A1 | Recovery of nickel and cobalt from ore | 59 |
| 6 | US4157943A | Composite electrode for electrolytic processes | 58 |
| 7 | US4272333A | Moving bed electrolysis | 54 |
| 8 | US5344479A | Upgrading copper sulphide residues containing nickel and arsenic | 48 |
| 9 | US5628817A | Method for leaching nickel-copper matte employing substantially neutral leaching solutions | 46 |
| 10 | WO2019060996A1 | Lithium-ion batteries recycling process | 45 |
Citation counts favour older documents in a searched corpus — treat this table as a map of foundational chemistry, not a ranking of current relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
Put your own technology through the same analysis
Eureka on the web
When you want the answer in the next five minutes.
The agent works the prompt against patents and technical literature, citing every source.
Run your analysis now →MCP server & REST API
When it has to run inside your own pipeline.
Patent search, landscape analysis and assignee resolution as MCP tools. Drop them into any agent framework, or call REST directly.
Browse MCP servers →What the data means for a filing decision
Three readings of the same dataset, each pointing at a different practical question: where the field is crowded, where it moved fastest, and where citation weight actually sits.
The head of the field is small and defined
Five assignees hold 275 of the 986 records in scope, with the leader alone at 80. That is a meaningfully concentrated position for a field this size — new entrants filing anode-chemistry or electrolyte-additive claims should expect to run into this group's prior art directly rather than finding open ground.
Filing pace has cooled from its 2019 peak
Activity peaked at 29 records in 2019 and had fallen to 7 by 2024, a 61% decline over the most recent complete three-year window. Whether that reflects consolidation around existing chemistry or a genuine slowdown in R&D investment is not something citation counts alone can answer.
Two IPC classes carry almost every filing
C25C (electrolytic metal production) and C22B (extraction & refining) each touch roughly half of all 986 records. Filings that combine both classes are effectively staking claims across the full electrowinning process chain, from leach solution to deposited metal — a pattern worth checking before drafting broad process claims.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to critical-mineral refining & separation: critical metal electrowinning patent landscape, with the prior art for and against each one.
Where to take this analysis next
This page maps where filings sit today. The next step is testing a specific claim or process route against that map before committing drafting time.
Check a draft claim against the leader's portfolio
Before drafting anode-coating or electrolyte-additive claims, run them against the top assignee's 80 records specifically, since that is where the densest prior art in this field sits.
Explore in Eureka →Track the under-claimed branches
Membrane-based pre-separation and rare-earth-specific electrolyte chemistry show thinner filing density than core anode chemistry — a narrower opportunity but a real one.
Explore in Eureka →Watch for the 2025-26 filing catch-up
Because publication lags filing by about 18 months, the apparent drop in 2025-26 records will partially reverse as more filings publish; revisit this trend rather than treating the current dip as final.
Explore in Eureka →Common questions about critical metal electrowinning patents
The assignee ranking behind this dataset covers 986 records, with the top-ranked assignee holding 80 of them — well ahead of the fifth-place holder at 37 and the tenth-place holder at 22. The top five assignees combined hold 275 records, or 27.9% of all 986 in scope, which is a meaningful concentration for a field of this size. Beyond the leading names the ranking thins into a long tail of assignees with far fewer filings each, so a newcomer's realistic competitive set is a small group rather than the entire ranked list.
Filings peaked at 29 records in 2019 and had fallen to 7 by 2024, a 61% decline over that most recent complete three-year window. The 2025 and 2026 figures in the raw data look even lower, but publication typically lags actual filing by around 18 months, so those two years are still incomplete and should not be read as confirming a further slowdown. The honest read is that the field cooled off its 2019 peak through 2024; whether it has stabilised or kept falling since then is not yet visible in published data.
Two IPC subclasses anchor the corpus: C25C, electrolytic metal production, appears in 49.5% of all 986 records, and C22B, metal extraction and refining, appears in 49.1%. Secondary classes — C25B (electrolytic production of compounds), C01G (metal compounds) and C25D (electroplating and electroforming) — each sit between 10% and 14% of records. Because a single filing can carry multiple IPC codes, these percentages overlap rather than summing to 100%, which itself signals that most substantive filings combine an extraction claim with an electrolytic-production claim.
US8357271B2, assigned to Doshisha, claims a zinc-and-cobalt electrowinning anode built around an amorphous iridium oxide catalytic layer, with a cobalt-specific variant using iridium oxide or ruthenium-based coatings, aimed at inhibiting manganese compound and cobalt oxyhydroxide deposition on the anode surface. The claims are drawn narrowly around this specific catalytic-layer chemistry and deposition-inhibition mechanism, not around electrowinning anodes generally. Work using different catalytic materials or targeting different deposition failure modes sits outside its literal claim scope, but any anode design using amorphous iridium oxide coatings for manganese or cobalt oxyhydroxide control should be checked against it directly.
The technology composition data shows B01D (separation processes), C01B (non-metallic elements and inorganic compounds) and H01M (batteries and cells) each covering under 10% of the 986 records, well behind the two dominant classes. That gap suggests membrane and filtration-based separation steps feeding into electrowinning, and rare-earth or scandium-specific electrolyte chemistry, are comparatively under-claimed relative to core anode and process chemistry. It is not evidence the ground is unclaimed everywhere in those branches, only that filing density there is markedly lower than in the C25C/C22B core.
Research Critical-Mineral Refining & Separation: Critical Metal Electrowinning Patent Landscape in depth with Eureka
Go past this page: query the whole critical-mineral refining & separation: critical metal electrowinning patent landscape corpus yourself, in your own scope.
Every answer comes back with patent numbers you can open.
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.