Capacitive Deionization Desalination Patent Landscape 2026
- Filing has cooled since its 2018 peak of 23. the midpoint year 2022 sits at 8, and the trend has not recovered — this is a field with an occupied core, not a growing one.
- Capacitor and electrode-material IPC classes trail water-treatment filings by a wide margin. H01G (capacitors) carries only 22 records against 243 in C02F, meaning most filers protect the water-treatment application, not the underlying electrode or capacitor architecture.
- The two most-cited patents predate the current filing wave by over a decade. US6309532B1 (368 citations) and US6346187B1 (106 citations) still anchor freedom-to-operate analysis for anyone filing electrode regeneration claims today.
Filing growth compares 2021 (6 records) with 2024 (13) — 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 243 records in scope (CR5), not by the ranked leaders only.
What the filings cover
Capacitive deionization (CDI) removes ions from water by applying a voltage across porous or membrane-coated electrodes, storing charge rather than driving a phase change. The search scope here centres on brackish water desalination, electrosorption and ion removal under the core CDI and membrane-CDI IPC classes (C02F1/469, C02F1/461, C02F103/08). Filings span 2015 through the 2026 cut-off, with publication lag meaning the final one to two years are undercounted.
243 patent families sit inside this scope, concentrated overwhelmingly in water and wastewater treatment classification (C02F) rather than in capacitor or electrode-materials classes. That split matters for freedom-to-operate work: a filer can occupy the water-treatment application claim while the underlying electrode chemistry remains comparatively open.
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Filing trend and jurisdiction spread
Annual filing counts, IPC composition and receiving-office totals for the 243 families in scope.
Filings peaked in 2018 and have not returned to that level
From 14 filings in 2017 to a peak of 23 in 2018, the trend falls to 8 at the 2022 midpoint and continues down toward a single filing in the partial 2026 year. Read the last one to two years as undercounted rather than as a genuine collapse, since publication lags filing by roughly 18 months — but the multi-year decline from 2018 through 2022 predates that lag and is real.
Water treatment dominates; capacitor and separation classes are secondary
C02F carries all 243 records by definition of scope, but B01D (separation processes, 42), C25B (electrolytic production, 24) and H01G (capacitors, 22) show where filers layer secondary claims. B01J, C01B, B03C and E03B each carry single digits to low double digits, indicating catalysis, inorganic-materials and magnetic/electrostatic-separation angles are rarely claimed alongside CDI.
Shares are the percentage of the 243 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Capacitive Deionization Desalination with Eureka
This page is one run against one query. Ask Eureka your own question about capacitive deionization desalination and every answer comes back with the patent numbers behind it.
Try EurekaThe prior art that still shapes freedom-to-operate
Desalination systems of photovoltaic direct-driven membrane capacitive deionization
The present disclosure relates to a desalination system of photovoltaic direct-driven membrane capacitive deionization. The system includes a photovoltaic direct-driven group and a municipal power grid-connected group. The photovoltaic direct-driven group includes a photovoltaic power collection unit, a power storage unit, a direct-driven power monitoring unit, a voltage adjustment unit, and a membrane capacitive deionization water purification unit. The municipal power grid-connected group includes a grid-connected control unit, a grid busbar unit, and an intelligent detection unit.Filed by Jiangsu Maymuse Environmental Technology Co., Ltd. — one of the more recent grants in the dataset, pairing off-grid solar power management with membrane-CDI desalination rather than claiming a new electrode chemistry.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US6309532B1 | Method and apparatus for capacitive deionization and electrochemical purification and regeneration of electro… | 368 |
| 2 | US6346187B1 | Alternating-polarity operation for complete regeneration of electrochemical deionization system | 106 |
| 3 | US20140346046A1 | Polarized Electrode for Flow-through Capacitive Deionization | 76 |
| 4 | US20040118780A1 | Water purification system and method | 47 |
| 5 | US7138042B2 | Alternating-polarity operation for complete regeneration of electrochemical deionization system | 46 |
| 6 | US6761809B2 | Alternating-polarity operation for complete regeneration of electrochemical deionization system | 44 |
| 7 | US20040188246A1 | Alternating-polarity operation for complete regeneration of electrochemical deionization system | 39 |
| 8 | US20020084188A1 | Alternating-polarity operation for complete regeneration of electrochemical deionization system | 38 |
| 9 | CN107624106A | 通过电容去离子进行连续的水脱盐和离子分离的方法及其单模块流动电极装置 | 30 |
| 10 | KR1020170002047A | Purification system for potable water and ultra pure water | 30 |
Citation counts favour older filings inside a searched corpus — treat this as a map of influence, not of current commercial relevance.
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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Browse MCP servers →What the numbers mean for a filing decision
Three read-throughs from the trend, classification and citation data above.
A field past its filing peak
The run from 14 filings in 2017 to 23 in 2018 and down to 8 by 2022 describes a technology whose core claim space filled early and has not reopened. New entrants are filing into a landscape shaped by decade-old anchor patents rather than a growing frontier.
Water-treatment claims outnumber capacitor claims 11-to-1
Nearly every record in scope sits in water/wastewater treatment classification; only 22 also touch capacitor classification (H01G). Electrode and capacitor architecture claims are comparatively thin, which is where a differentiated filing is more likely to clear prior art.
Two early patents still anchor the field
US6309532B1 and US6346187B1 together account for far more citations than any filing from the last decade. Any regeneration or alternating-polarity claim should be checked against both before drafting.
Filing is US- and Europe-weighted
United States (79) and EPO (49) receive far more filings than China (23), India (10) or South Korea (10), despite CDI's relevance to brackish and industrial water treatment in water-stressed regions. That imbalance is worth checking against target-market enforcement plans.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to capacitive deionization desalination, with the prior art for and against each one.
| Assignee | Co-assignee | Shared families |
|---|---|---|
| Gore Enterprise Holdings, Inc. | SULLIVAN JAMES P | 3 |
| Zion Tech Co., Ltd. | Kyungdong Navien Co., Ltd. | 3 |
| Gore Enterprise Holdings, Inc. | ZUCKERBROD DAVID | 1 |
| Gore Enterprise Holdings, Inc. | MURTHY MAHESH | 1 |
| Gore Enterprise Holdings, Inc. | LEFFEW MARSHALL | 1 |
| Gore Enterprise Holdings, Inc. | KNAPP SEAN | 1 |
| Gore Enterprise Holdings, Inc. | JOHNSON WILLIAM B | 1 |
| Gore Enterprise Holdings, Inc. | HARDWICK STEVE | 1 |
Only 8 co-assignee pairs appear across 243 families, the strongest being a corporate–individual inventor pair filed together three times — co-development partnerships are the exception, not the norm, in this field.
Who holds the claim space, and who has stopped filing
Recent-year momentum shows a field where established assignees have gone quiet rather than one being displaced by new entrants.
No tracked assignee filed in the latest year
Every assignee in the recent-momentum list — including 三星电子 (Samsung Electronics), 戈尔企业控股 (Gore) and VWS UK — shows zero filings in the most recent year. Given the 18-month publication lag, some of this is timing, but the multi-year decline visible in the trend data suggests it is not only that.
Corporate–inventor pairs, not corporate–corporate alliances
The two strongest co-assignee pairs pair a corporate holder with a named individual inventor, or pair two Korean corporate entities together. Cross-company joint development is not a visible pattern in this dataset.
Early movers still define the reference set
The most heavily cited records date from the field's formative period and describe core electrosorption and alternating-polarity regeneration methods. Recent filers build applications — solar-driven systems, membrane configurations — on top of that base rather than replacing it.
| Assignee | Recent year | YoY |
|---|---|---|
| Samsung Electronics Co., Ltd. (Korea) | 0 | — |
| Stockholm Voltea Technology Company | 0 | — |
| DWI – Leibniz Institute for Interactive Materials | 0 | — |
| Aqua Water Systems LLC | 0 | — |
| Gore Enterprise Holdings, Inc. | 0 | — |
| VWS UK | 0 | — |
| Doosan Heavy Industries & Construction Co., Ltd. | 0 | — |
| Zion Tech Co., Ltd. | 0 | — |
Where to take this
Two directions depend on whether the goal is defensive clearance or a new filing.
Clear freedom-to-operate against the anchor patents
Any alternating-polarity or electrode regeneration claim should be checked against US6309532B1 and US6346187B1 before drafting, since both remain the highest-cited records in the corpus and shape most subsequent claim language.
Run a prior-art search in EurekaScope a filing into the under-claimed capacitor and materials classes
With H01G, B01J, C01B and B03C all carrying far fewer records than the core C02F water-treatment class, a claim tied to electrode material or capacitor architecture rather than the water-treatment application may face a lighter prior-art field.
Map the white space in EurekaCommon questions on CDI desalination patents
The core patent classes are C02F1/469 and C02F1/461, covering water and wastewater treatment by electrical or electrochemical methods, alongside C02F103/08 for brackish water specifically. Within this dataset of 243 patent families, the two most-cited records — US6309532B1 and US6346187B1 — describe the foundational capacitive deionization apparatus and its alternating-polarity electrode regeneration method. Most active filing today builds application-level claims, such as membrane configurations or power-management systems, on top of that base rather than re-claiming the core electrosorption mechanism.
Filing peaked in 2018 at 23 records and has declined since, falling to 8 at the 2022 midpoint and continuing downward toward the 2026 cut-off. Because publication lags filing by roughly 18 months, the most recent one to two years are understated in any raw count. Even allowing for that lag, the multi-year decline from 2018 through 2022 indicates the field's filing activity has cooled from its peak rather than continuing to accelerate.
Recent-year momentum data shows established assignees including Samsung Electronics, Gore, VWS UK and the DWI Leibniz Institute for Interactive Materials all recorded zero filings in the most recent tracked year. This does not necessarily mean these organisations have abandoned the space — publication lag affects the newest filings most — but it does mean the visible, recently active filer base is thin. Co-filing between separate companies is also rare, with only 8 co-assignee pairs found across the 243 families in scope.
The clearest gap is between the water-treatment application classification (C02F, carrying all 243 records by definition of scope) and the underlying capacitor or electrode-materials classifications, which are comparatively sparse — H01G (capacitors) carries only 22 records, B01J (catalysis) 11, C01B (inorganic materials) 8, and B03C (magnetic/electrostatic separation) just 4. A claim tied to novel electrode capacitor architecture, catalytic pre-treatment integration, or renewable-power-driven system design is likely to encounter a lighter prior-art field than a claim on the core desalination method itself.
Membrane CDI adds ion-exchange membranes adjacent to the electrodes to improve charge efficiency and reduce co-ion leakage, and it is captured within the same core IPC classes as CDI in this dataset. Recent filings such as US12202748B2, which pairs a photovoltaic direct-driven power system with a membrane-CDI water purification unit, illustrate how newer claims tend to combine MCDI with system-level features — power management, grid integration — rather than claiming new membrane chemistry outright. Reviewing both the CDI and MCDI terms together is necessary for a complete freedom-to-operate picture, since assignees often file broadly across both.
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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.