Capacitive Deionization Reliability Patents: Leaders & Gaps 2026
- No dominant assignee has emerged. the strongest co-filing pair appears only twice, and momentum for the most active filers sits flat at 0% YoY — this is still an open field, not a consolidated one.
- Filing peaked in 2025 at 8 records after a flat middle stretch (4 in 2022), so the field only recently accelerated — read the partial 2026 count as an undercount, not a slowdown.
- China and the United States each hold 14 receiving-office filings with India a distant third at 5 — durability claims are being contested in two jurisdictions almost equally, unlike many CDI desalination filings concentrated in one.
Filing growth compares 2021 (1 records) with 2024 (2) — 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 37 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Capacitive deionization (CDI) removes ions from water by applying voltage across porous electrodes, then reversing polarity to regenerate them. The engineering problem this dataset isolates is not desalination performance itself but what fails over repeated cycles: electrode degradation, loss of cycling stability, fouling of the electrode surface, and the durability of the regeneration step. That is a narrower and more technically demanding claim space than CDI filings generally.
The corpus is small — 37 patent families — and concentrated almost entirely in the water-treatment IPC subclass, with a secondary cluster in capacitor hardware. That combination signals a field where the electrochemistry of the electrode, not the system architecture, is where the durability problem is actually being fought over.
Filing trend and technology composition
Two views of the same 37-family corpus: how filing activity has moved year over year, and which IPC subclasses the claims actually sit in.
Filing trend, 2017–2026
Filings ran flat through the middle of the window (2 in 2017, 4 by 2022) before climbing to a peak of 8 in 2025. The 2026 figure of 3 is a partial year under the standard 18-month publication lag, so the real trajectory is very likely still rising rather than falling.
IPC subclass distribution
Every record in this set sits under C02F (water and wastewater treatment), confirming the search is tightly scoped to CDI durability rather than general capacitor or filtration art. H01G (capacitors) is the largest secondary cluster at 9 records, followed by smaller groups in separation processes, catalysis, and inorganic compounds — evidence that electrode material chemistry, not device packaging, carries most of the inventive activity.
Shares are the percentage of the 37 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
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Try EurekaThe most-cited prior art in this space
Potential of zero charge-based capacitive deionization
The invention is a capacitive, aka electrostatic, deionization apparatus and method that solves the problem of short lifetime of conventional capacitive deionization (CDI) and of membrane capacitive deionization (MCDI) devices and methods by shifting the Potential of Zero Charge of electrode surfaces through surface modifications. Such electrode surface modifications provide very long lifetime capacitive deionization devices and methods.US10793450B2 — University of Kentucky Research Foundation — granted 2020-10-06.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20140346046A1 | Polarized Electrode for Flow-through Capacitive Deionization | 76 |
| 2 | US20190225513A1 | Carbon electrodes based capacitive deionization for the desalination of water | 22 |
| 3 | CN112062229A | 一种Bi/MOF衍生多孔碳球复合材料及其制备方法、应用 | 20 |
| 4 | US20160167984A1 | Potential of Zero charge-Based Capacitive Deionization | 17 |
| 5 | US20210107810A1 | Electrically conductive polymer thin-films | 6 |
| 6 | US20190144310A1 | Flow-through electrode capacitive deionization cell | 5 |
| 7 | US10793450B2 | Potential of zero charge-based capacitive deionization | 5 |
| 8 | US10294131B2 | Polarized electrode for flow-through capacitive deionization | 5 |
| 9 | CN115636475A | 硒化钼/介孔中空碳球复合电极材料及其制备方法和应用 | 4 |
| 10 | CN217555865U | 一种铜离子氧化还原电解质构筑的多通道电容脱盐装置 | 4 |
Citation counts favour older filings simply because they have had more time to be cited; treat this as a map of influence on the field to date, not 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 read-outs from the citation, geography and IPC data that matter more than the raw family count.
One early filing still sets the reference frame
The flow-through polarized electrode patent from 2014 carries far more citations than anything filed since, including the next most-cited record at 22. New filers in this space are almost certainly designing around or building on this document whether they cite it explicitly or not.
Contested evenly across two offices
China and the United States each account for 14 receiving-office filings, with no other jurisdiction close — India sits at 5. A durability claim cleared in one of these two offices gives no assurance of freedom to operate in the other.
Water-treatment framing dominates the claim language
Every record in the set is classified under C02F, and the next-largest bucket, H01G capacitors, holds only 9. Durability claims are being written and examined as water-treatment inventions first, capacitor-hardware inventions second — a distinction that matters for claim strategy and examiner assignment.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to capacitive deionization reliability and durability, with the prior art for and against each one.
Who is filing, and how connected are they
No single assignee anchors this space. Co-filing is thin — 10 pairs total, none stronger than two shared filings — and recent-year momentum for the most active names is flat.
REVA UNIV / MAHIMA S
This pairing is the strongest co-assignee link in the dataset at two shared filings, and both names carry one filing in the latest year. Flat year-over-year growth suggests steady, incremental output rather than an accelerating program.
Foundational art, currently quiet
The Kentucky group holds the representative potential-of-zero-charge filing underpinning much of the field's electrode-surface-modification approach, plus two distinct co-assignee links, but shows no filings in the most recent year on record.
A dispersed field, not a consolidated one
With 37 families and no assignee showing sustained multi-year output, this looks like an emerging research niche where individual labs and small teams, rather than incumbents, are still staking out the durability-specific claim space.
| Assignee | Recent year | YoY |
|---|---|---|
| REVA UNIV | 1 | 0% |
| MAHIMA S | 1 | 0% |
| University of Kentucky Research Foundation | 0 | — |
| Mespilus Inc. | 0 | — |
| Lawrence Livermore National Security, LLC | 0 | — |
| Zhejiang University of Technology | 0 | — |
| UChicago Argonne, LLC | 0 | — |
| UT-Battelle, LLC | 0 | — |
Where to take this analysis
The landscape points to specific next questions depending on whether you are filing, licensing, or scoping freedom to operate.
Stress-test a claim against the cited core
Run a candidate electrode-durability claim against the highest-cited records in this set, particularly the 2014 flow-through electrode filing, before drafting.
Explore in Patsnap EurekaTrack the under-claimed branches
Fouling-resistant coatings and regeneration-cycle energy recovery show thin filing density relative to core electrode-degradation art — worth monitoring for new entrants.
Set up monitoring in Patsnap EurekaWatch the China/US filing balance
With filings split evenly between China and the United States, freedom-to-operate work needs to cover both offices rather than defaulting to one.
Run an FTO search in Patsnap EurekaCommon questions on CDI reliability patents
The core prior art centres on electrode surface chemistry and the potential of zero charge, exemplified by US10793450B2 from the University of Kentucky Research Foundation, which addresses short device lifetime through electrode surface modification. The most-cited filing in the broader set, US20140346046A1, covers a polarized flow-through electrode design and functions as a reference point that later filings build on or design around. Most of this art is classified under C02F rather than pure capacitor hardware, meaning claims tend to be written around the water-treatment process rather than the electrode as a standalone capacitor component.
No single assignee dominates this space; the dataset spans 37 patent families with no sustained multi-year leader. The strongest co-filing relationship, between REVA UNIV and an individual inventor, appears in only two shared filings, and the University of Kentucky Research Foundation holds foundational art but shows no filings in the most recent year. This points to a field still populated by individual research groups and universities rather than consolidated corporate portfolios.
Fouling-resistant membrane coatings, regeneration-cycle energy recovery, conductive polymer thin-film electrodes, and in-situ potential-of-zero-charge monitoring all show thinner filing density than the core electrode-degradation art. These are adjacent to well-covered ground but not yet heavily claimed, based on the current IPC and citation distribution. A new filing targeting one of these branches would need to differentiate clearly from the potential-of-zero-charge and flow-through electrode prior art that anchors the field.
Filing activity stayed flat through the middle of the tracked period, reaching only 4 records by 2022, before climbing to a peak of 8 in 2025. Because patent publication typically lags filing by around 18 months, the partial 2026 figure of 3 almost certainly understates actual filing activity for that year rather than indicating a genuine slowdown. The pattern is consistent with durability and fouling-resistance research maturing later than core CDI desalination work.
China and the United States are tied as the leading receiving offices at 14 filings each, far ahead of India at 5, the European Patent Office at 3, and a single PCT/WIPO filing. This even split means that clearing a durability claim in one of the two leading offices provides no assurance of freedom to operate in the other, so competitive and freedom-to-operate searches for this technology need to cover both jurisdictions rather than treating either as dominant.
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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.